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(11) | EP 1 431 409 A1 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Free cutting alloy |
(57) Provided is free cutting alloy excellent in machinability, preserving various characteristics
as alloy. The free cutting alloy contains: one or more of Ti and Zr as a metal element
component; and C being an indispensable element as a bonding component with the metal
element component, wherein a (Ti,Zr) based compound including one or more of S, Se
and Te is formed in a matrix metal phase. The free cutting alloy is more excellent
in machinability, preserving various characteristics as alloy at similar levels to
a conventional case. The effect is especially conspicuous, for example, when a compound
expressed in a chemical form of (Ti,Zr)4C2(S,Se,Te)2 as the (Ti,Zr) based compound is formed at least in a dispersed state in the alloy
structure. |
Background Art
Summary of the Invention
Brief Description of the Drawings
Fig. 1 is a graph showing compositional regions in combination of a content of one or more of Ti and Zr, a content of C and a content of one or more of S, Se and Te in a free cutting alloy of the present invention constituted as electromagnetic stainless alloy;
Fig. 2 is a graph showing an X-ray diffraction chart of an inventive steel specimen No. 5 in experiment of Example 1;
Fig. 3 is an optical microphotograph of the third selection inventive steel specimen No. 2 in Example 3;
Fig. 4 is a graph showing EDX analytical results of a second selection inventive specimen No.2 in Example 2;
Fig. 5 is optical microphotograph of second selection inventive steels specimen Nos. 2 and 13 in Example 2;
Fig. 6 is a representation describing measuring points for a hardness test in Example 2;
Fig. 7 is a graph showing an example of Schaeffler diagram;
Fig. 8 is graphs showing EDX analytical results of a third selection inventive steel specimen No.2 in experiment of Example 3;
Fig. 9 is an optical microphotograph of the first selection inventive steel specimen No.5 in Example 1;
Fig. 10 is a graph showing a relation between B1 or Hc and α in Example 4;
Fig. 11 is a graph showing a relation between a boring time or a cracking threshold working ratio and α in Example 4;
Fig. 12 is a graph showing a relation between a pitting potential (Vc) and α in Example 4;
Fig. 13 is a graph showing dependencies of solubility products on temperature of components of TiO, TiN, Ti4C2S2, TiC, TiS and CrS in γ-Fe;
Fig. 14 is an optical microphotograph of a fifth selection inventive steel specimen No. 30 in Example 5;
Fig. 15 is a graph showing a relation between a range of parameters of X and Y and evaluation results on hot workability in Example 5; and
Fig. 16 is a graph showing a relation between a drill boring time and Y in mass % of an alloy in Example 5.
Preferred Embodiments of the Invention
(1) The Ti and Zr content being defined such that WTi + 0.52 WZr = 0.03 to 3.5 mass %,
wherein WTi and WZr denote respective contents in mass % of Ti and Zr
Ti and Zr are indispensable elements for forming a (Ti,Zr) based compound playing
a central role in exerting the effect of improving machinability of a free cutting
alloy of the present invention. When a value of WTi + 0.52 WZr is lower than 0.03 mass %, the (Ti,Zr) based compound is insufficiently formed in
amount, thereby disabling the effect of improving machinability to be satisfactorily
exerted. On the other hand, when in excess of the value, machinability is reduced
on the contrary. For this reason, the value of WTi + 0.52 WZr is required to be suppressed to 3.5 mass % or lower. The above effect exerted when
Ti and Zr are added into an alloy is determined by the sum of the numbers of atoms
(or the sum of the numbers of values in mol), regardless of kinds of metals, Ti or
Zr. Since a ratio between atomic weights is almost 1 : 0.52, Ti of a smaller atomic
weight exerts a larger effect with a smaller mass. Thus, a value of WTi + 0.52 WZr is said to be compositional parameter reflects the sum of the numbers of atoms of
Zr and Ti included in an alloy.
(2) One or more of S and Se in the respective ranges of 0.01 to 1 mass % for S and
0.01 to 0.8 mass % for Se
S and Se are elements for useful in improving machinability. By adding S and Se into
an alloy, in an alloy structure, formed is a compound useful for improving machinability
(for example, a (Ti,Zr) based compound expressed in the form of a composition formula
(Ti,Zr)4(S,Se)2C2). Therefore, contents of S and Se are specified 0.01 mass % as the lower limit. When
the contents are excessively large, there arises a chance to cause a problem of deteriorating
hot workability and therefore, there have to be the upper limits: It is preferable
that a S content is set to 1 mass % and a Se content is set to 0.8 mass % as the respective
upper limits. Further, S and Se are both desirably added into an alloy in a necessary
and sufficient amount in order to form a compound improving machinability of the alloy,
such as the above described (Ti,Zr) based compound. An excessive addition of S results
in deterioration of the out-gas resistivity.
The free cutting alloy can contain: 2 mass % or lower, including zero, Ni; 12 to 35 mass % Cr; and 0.005 to 0.4 mass % C.
(3) 0.005 to 0.4 mass % C
C is an important element forming a compound improving machinability. When a content
thereof is lower than 0.005 mass %, however, an effect exerting sufficient machinability
can not be imparted to the alloy, while when in excess of 0.4 mass %, much of a single
carbide not effective for improving machinability is formed. Addition of C is preferably
set in the range of 0.01 to 0.1 mass %, wherein it is preferable that addition of
C is adjusted so properly that the effect of imparting machinability on the alloy
is optimized depending on an amount of a constituting element of a compound improving
machinability such as a (Ti,Zr) based compound.
(4) 2 mass % or lower, including zero Ni
Ni can be added according to a necessity since the element is effective for improving
corrosion resistivity, particularly in an environment of a reducing acid. Excessive
addition, however, not only reduce stability of a ferrite phase, but also causes cost-up
and therefore, a content thereof has the upper limit of 2 mass %, wherein a case of
no addition of Ni may be included.
(5) 12 to 35 mass % Cr
Cr is an indispensable element for ensure corrosion resistivity and is added in the
range of 12 mass % or higher. On the other hand, excessive addition is not only harmful
to hot workability but also causes reduction in toughness and therefore the upper
limit is set to 35 mass %.
The free cutting alloy can contain: 2 mass % or lower, including zero, Ni; 9 to 17
mass % Cr; and C satisfying the following formulae:
and
(6) 2 mass % or lower, including zero Ni
Ni can be added according to a necessity since the element is effective for improving
corrosion resistivity, particularly in an environment of a reducing acid. Excessive
addition, however, not only reduces a martensitic transformation temperature (Ms point),
but also increases stability of an austenitic phase of the matrix phase excessively,
whereby a case arises in which an amount of martensite necessary to ensure hardness
is hard to be obtained. Moreover, hardness after annealing becomes high producing
a solid solution hardening effect caused by Ni in excess, which sometimes makes performances
such as machinability decrease. For the above described reason, a Ni content has the
upper limit of 2 mass %.
(7) 9 to 17 mass % Cr
Cr is an indispensable element for ensuring corrosion resistivity and added 9 mass
% or higher in content. However, when a content is in excess of 17 mass %, phase stability
is deteriorated and thereby high temperature brittleness occurs with ease, leading
to poor hot workability. Moreover, it is considered that as the content increases,
toughness decreases. Especially, when a stainless steel including Cr in excess receives
a long heat treatment at a temperature in the intermediate range of 400 to 540°C,
toughness at room temperature is lost with ease. A Cr content is desirably set in
the range of 11 to 15 mass % and more desirably in the range of 12 to 14 mass %.
(8) 2 mass % or lower, including zero Si
Si is added as a deoxidizing agent for steel. That Si is added in excess, however,
is unfavorable because not only cold workability is deteriorated, but formation of
δ ferrite increases in amount, thereby degrading hot workability of steel. Moreover,
a Ms point decreases in excess in a case of martensite containing stainless steel.
Consequently, a Si content has the upper limit of 2 mass %. In a case where cold workability
is particularly regarded as important, the Si content is preferably set 0.5 mass %
or lower, including zero.
(9) 2 mass % or lower, including zero Mn
Mn acts an deoxidizing agent for steel. In addition, since a compound useful for increase
in machinability in co-existence with S or Se, there arises a necessity of addition
when machinability is highly thought of. On the other hand, since MnS especially deteriorates
corrosion resistivity, affects cold workability adversely and moreover, reduces a
Ms point excessively in martensite containing stainless steel, therefore a Mn content
has the upper limit of 2 mass %. Especially when corrosion resistivity and cold workability
are regarded as important, a Mn content is desirably limited to 0.4 mass % or lower,
including zero.
(10) 2 mass % or lower, including zero Cu
Cu can be added according to a necessity since the element is effective for improving
corrosion resistivity, particularly in an environment of a reducing acid. It is preferable
to contain 0.3 mass % or higher in order to obtain a more conspicuous effect of the
kind. When in excess, however, not only does hot workability decrease, but in martensite
containing stainless steel, a Ms point decreases and quenchability is also deteriorated,
whereby it is preferable for a Cu content to be set 2 mass % or lower, including zero.
Especially when hot workability is regarded as important, it is more desirably to
suppress the Cu content to 0.5 mass % or lower, including zero.
(11) 2 mass % or lower, including zero Co
Co is an element effective for improving corrosion resistivity, particularly in an
environment of a reducing acid and in addition, can also be added to martensite containing
stainless steel depending on a necessity since Co increases a Ms point and improves
quenchability. To contain Co in content equal to 0.3 mass % or higher is preferable
in order to obtain more of conspicuousness in the effects. When added in excess, however,
not only does hot workability decrease, but a raw material cost increases, and therefore,
it is preferable to set a content of Co in the range of 2 mass % or lower, including
zero. Especially when hot workability and decrease in raw material cost are regarded
as important, a content of Co is more desirably suppressed to 0.5 mass % or lower,
including zero.
(12) One or more of Mo and W in the respective ranges of 0.1 to 4 mass % for Mo and
0.1 to 3 mass % for W
Since Mo and W can further increase corrosion resistivity and a strength, the elements
may be added according to a necessity. The lower limits are both 0.1 %, where the
effects thereof become clearly recognized. On the other hand, when added in excess,
not only is hot workability deteriorated, but in martensite containing stainless steel,
a Ms point decrease excessively and further cost increases and therefore, the upper
limits of Mo and W are set 4 mass % and 3 mass %, respectively.
(1) Austenitic stainless steel is stainless steel showing an austenitic structure even in room temperature and can be exemplified as follows: SUS 201, SUS 202, SUS 301,SUS 301J, SUS 302, SUS 302B, SUS 304, SUS 304N1, SUS 304N2, SUS 305, SUS 309S, SUS 310S, SUS 316, SUS 316N, SUD 316J1, SUS 317, SUS 317J1, SUS 321, SUS 347, SUS XM15J1, SUS 836L, SUS 890L and so on.
(2) Austenitic-ferritic stainless steel is stainless steel showing a dual phase structure of austenite and ferrite and can be exemplified SUS 329J4L and so on.
(3) Precipitation hardening stainless steel is a stainless steel obtained by adding elements such as aluminum and copper, and precipitating a compound with the elements as main components by a heat treatment to harden and can be exemplified SUS 630, SUS 631 and so on. It should be appreciated that a concept of "stainless steel" includes heat resisting steel exemplified below as well:
(4) Austenitic heat resisting steel
Compositions are stipulated in JIS G 4311 and G 4312, for example, and can be exemplified
as follows: SUS 31, SUH 35, SUH 36, SUH 37, SUH 38, SUH 309, SUH 310, SUH 330, SUH
660, SUH 661 and so on.
(13) 2 to 50 mass % Ni
Ni is necessary to be added to stainless steel in a content of at least 2 mass % in
order to stabilize an austenitic phase in the stainless steel. Moreover, while Ni
has many chances to be added into the matrix since Ni is useful for improving corrosion
resistivity in an environment of a reducing acid, it is preferable to add at 2 mass
% or higher in content from the viewpoint of improvement on corrosion resistivity.
Moreover, when non-magnetism is desired, a necessary amount of Ni is required to be
added so as to stabilize an austenitic phase more and thereby obtain an alloy as austenite
containing stainless steel, considering connection with contents of other elements
such as Cr and Mo. In this case, a Schoeffler diagram shown in Fig. 7 can be utilized
for determination of the Ni content. An austenite forming element and a ferrite forming
element are converted to equivalents of Ni and Cr amounts and a relationship between
the equivalents and the structure is shown in Fig. 7 (see Revised 5th version Kinzoku Binran (Metal Hand Book) published by Maruzen in 1990, p. 578). However,
it is required to obtain a necessary amount of Ni in consideration of exclusion of
an amount in Ti and/or Zr compound from constituting elements of the matrix. Since
not only does excessive addition of Ni result in cost-up, but specific characteristics
as stainless steel are also degraded, a Ni content is limited to 50 mass % or lower.
(14) 12 to 50 mass % Cr
Cr is an indispensable element for ensuring corrosion resistivity of stainless steel.
Hence, Cr is added in a content equal to 12 mass % or higher. When a Cr content is
lower than 12 mass %, corrosion resistivity as stainless steel cannot be ensured due
to intergranular corrosion caused by increased sensitivity at grain boundaries. On
the other hand, when added in excess, there arises a risk that not only is hot workability
degraded, but toughness is also reduced due to formation of a compound such as CrS.
Furthermore, a problem occurs since high temperature embrittlement becomes conspicuous,
therefore a Cr content is limited to 50 mass % or lower. For this reason, a Cr content
is preferably set in the range of 12 to 50 mass % and performances specific to stainless
steel are, in a case, degraded outside the range in content of Cr. Desirably, a Cr
content is set in the range of 15 to 30 mass % and more desirably in the range of
17 to 25 mass %.
(15) 5 to 85.95 mass % Fe
Fe is an indispensable component for constituting stainless steel. Therefore, a Fe
content is at 5 mass % or higher. When an Fe content is lower than 5 mass %, the Fe
content is not preferable since no strength specific to stainless steel can be obtained.
That an Fe content exceeds 85.95 mass % is impossible in connection with required
contents of other components. Consequently, an Fe content is in the range of 5 to
85.95 mass %. An Fe content is desirably set in the range of 15 to 75 mass % and more
desirably in the range of 40 to 65 mass %.
(16) 0.01 to 0.4 mass % C
C is an indispensable component for improvement on machinability and added in a content
of 0.01 mass % or higher. With C being included in the matrix, a (Ti,Zr) based compound
is formed, and formation of the compound is considered to improves machinability of
stainless steel. When a C content is lower than 0.01 mass %, formation of the (Ti,Zr)
based compound is insufficient and the effect of improving machinability is not sufficiently
attainable. On the other hand, when the content exceeds 0.4 mass %, a carbide not
useful for improvement on machinability is excessively formed and therefore, machinability
is deteriorated on the contrary. It is considered that residual C not included, as
a constituting element, in the(Ti,Zr) based compound contributing to improvement on
machinability is dissolved in the matrix phase of stainless steel in a solid state
and the residual C in solid solution gives birth to an effect of increasing a hardness
of the stainless steel as well. Therefore, a C content is preferably set in a proper
manner taking into consideration not only that C is added such that a machinability
improvement effect is exerted in best conditions according to an amount of constituting
elements of a compound improving machinability, such as the (Ti,Zr) based compound,
but also the effect of improving hardness exerted by the residual C dissolved in a
solid solution state in the matrix phase. In consideration of the above described.
circumferences, a C content is desirably in the range of 0.03 to 0.3 mass % and more
desirably in the range of 0.05 to 0.25 mass %.
In a free cutting alloy of the present invention constituted as austenite containing
stainless steel, a composition may have the following components and contents thereof
in order to achieve better characteristics. That is, the composition can be 4 mass
% or lower, including zero Si; 4 mass % or lower, including zero Mn; 4 mass % or lower,
including zero Cu; and 4 mass % or lower, including zero Co. Description will be given
of the reason why the composition has the elements and contents thereof as follows:
(17) 4 mass % or lower, including zero Si
Si can be added as a deoxidizing agent for steel. However, when a content of Si is
excessive high, not only is a hardness after solid solution heat treatment disadvantageously
high, which in turn leads to poor cold workability, but an increased amount of a δ-ferrite
phase is formed, thereby deteriorating hot workability of the steel. Hence, the upper
limit of Si in content is set to 4 mass %. Especially, when cold workability and hot
workability are both regarded as important characteristics, a Si content is desirably
set to 1 mass % or lower and more desirably to 0.5 mass % or lower, including zero.
(18) 4 mass % or lower, including zero Mn
Mn not only acts as a deoxidizing agent of the steel, but also exerts an effect to
suppress formation of a δ-ferrite phase. Furthermore, Mn has an effect to stabilize
an austenitic phase. Since Mn forms a compound useful for increase in machinability
in co-existence with S and Se, Mn may added to the matrix when machinability is regarded
as an important characteristic. When an effect of improving machinability is expected
to be conspicuous, a Mn content is preferably set to 0.6 mass % or higher. When Mn
is added, MnS is formed with ease. However, since MnS not only degrades corrosion
resistivity to a great extent, but also reduces cold workability, formation of MnS
is unwelcome. Therefore, the Mn content is set to 4 mass % or lower, including zero.
Especially, when corrosion resistivity and cold workability are both regarded as important
characteristics, the Mn content is desirably set to 1 mass % or lower, including zero
and more desirably to 0.5 mass % or lower, including zero.
(19) 4 mass % or lower, including zero Cu
Cu is not only useful for increase in corrosion resistivity, particularly for improving
corrosion resistivity in an environment of a reducing acid, but also reduces work
hardenability and improves moldability. Moreover, since an antibacterial property
can be improved by a heat treatment or the like processing, Cu may added if necessary.
However, when Cu is excessively added, hot workability is degraded and therefore,
a Cu content is preferably set to 4 mass % or lower, including zero. Especially, when
hot workability is regarded as an important characteristic, the Cu content is more
desirably set to 1 mass % or lower, including zero.
(20) 4 mass % or lower, including zero Co
Co is an element not only useful for improving corrosion resistivity, particularly
in an environment of a reducing acid, but to exert an effect of ensuring non-magnetism
and therefore, may added to the matrix if necessary. It is preferable to add in content
of 1 mass % or higher in order to obtain more of conspicuousness of the effect. However,
when Co is added in excess, not only is hot workability reduced but cost-up occurs
on raw material. Hence, a Co content is preferably set to 4 mass % or lower, including
zero. Especially, when hot workability or cost is taken seriously, the Co content
is more desirably suppressed to 0.3 mass % or lower, including zero.
In the third selection invention constituted as austenite containing stainless steel,
the stainless steel can contain one or more of Mo and W in the respective ranges of
0.1 to 10 mass % for Mo and 0.1 to 10 mass % for W. Addition of Mo and W can improve
corrosion resistivity due to strengthened passivation and furthermore attain improved
hardness due to second hardening. It is preferable to add Mo and W in each content
of 0.1 mass % or higher in order to make the effect exerted clearly. On the other
hand, when in excess, hot workability is reduced and therefore, the content of Mo
and W combined is preferably set to 10 mass % as the upper limit.
(21) 0.05 mass % or lower, including zero P
P is segregated at grain boundaries and not only increases intergranular corrosion
sensibility but also sometimes reduces toughness. Therefore, a P content is preferably
set as low as possible and to 0.05 mass % or lower, including zero. Although the P
content is more desirably set to 0.03 mass % or lower, including zero, reduction in
content more than necessary has a chance to be reflected on increased production cost.
(22) 0.03 mass % or lower, including zero O
O combines with Ti or Zr both of which are constituting elements of a compound useful
for improving machinability and forms oxides not useful for improving machinability.
Therefore, an O content should be suppressed as low as possible and is set to 0.03
mass % as the upper limit. The O content is desirably set to 0.01 mass % or lower
if allowable in consideration of increase in production cost.
(23) 0.05 mass % or lower, including zero N
N combines with Ti or Zr both of which are constituting elements of a compound useful
for improving machinability and forms nitrides not useful for improving machinability.
Therefore, a N content should be suppressed as low as possible and is set to 0.05
mass % as the upper limit. The N content is desirably set to 0.03 mass % or lower,
including zero and more desirably to 0.01 mass %, if allowable in consideration of
increase in production cost.
(24) One or more of Te, Bi and Pb in the respective ranges of 0.005 to 0.1 mass %
for Te; 0.01 to 0.2 mass % for Bi; and 0.01 to 0.3 mass % for Pb
Since Te, Bi and Pb can further improve machinability, the elements may add if necessary.
The lower limits thereof at which the respective effects are exerted to clearness
are as follows: 0.005 mass % Te; 0.01 mass % Bi and 0.01 mass % Pb, respectively.
On the other hand, since excessive addition reduces hot workability, the upper limits
are set as follows: 0.1 mass % Te; 0.2 mass % Bi; and 0.3 mass % Pb.
(25) 0.01 to 3 mass % Si
Si is useful not only as a deoxidizing agent, but also for contributing to increase
in the maximum magnetic permeability and reduction in coercive force among soft magnetic
characteristics as an electromagnetic stainless steel and furthermore, useful for
increase in electric resistivity and improvement on responsibility in a high-frequency
band, and therefore, Si is added for the purposes. While a Si content is necessary
to be 0.01 % or higher in order to attain the effect, since when the content is excessive
high, hardness increases and cold workability is degraded, the content is reduced
when cold workability is regarded as a more important characteristic and intended
increases in the soft magnetic characteristics and a high-frequency responsibility
are compensated mainly by addition of Al, described later, corresponding to decrease
in Si content. However, when machinability is regarded as an important characteristics,
the upper limit of the Si content is set to 3 mass %.
(26) 2 mass % or lower Mn
Mn is an element useful as a deoxidizing agent, but since when a Mn content exceeds
2 mass %, soft magnetic characteristics are degraded, the Mn content is set to 2 mass
% or lower.
(27) 5 to 25 mass % Cr
Cr is useful for improvement on corrosion resistivity and electric resistivity of
steel, but for improvement on machinability by forming Cr(S,Se,Te) with S, Se and
Te, which will be described later. Therefore, Cr is added for the improvements. Although
it is necessary for Cr to be included in the range of 5 mass % or higher, the Cr content
in excess of 25 mass % reduces cold workability and accordingly, the Cr content is
set to 5 to 25 mass %.
(28) 0.01 to 5 mass % Al
A1 is useful not only as a deoxidizing agent, but for contributing increase in the
maximum magnetic permeability and reduction in coercive force and furthermore, useful
for increase in electric resistivity and improvement on responsibility in a high-frequency
band, similar to Si. Therefore, Al is included for the improvements. Although it is
necessary for Al to be included exceeding 0.01 mass % in order to exert the effects,
not only a specific refining method is required but cold workability is also degraded
when an A1 content exceeds 5 mass % and accordingly, the Al content is set to from
0.01 to 5 mass %.
(29) One or more of Ti and Zr in the range of 0.05 to 0.5 mass % in terms of Ti %
+ 0.52 Zr % = X
Ti and Zr forms (Ti,Zr)4C2(S,Se,Te)2 and/or (Ti,Zr)(S,Se,Te) in co-existence with C, S, Se and Te to contribute to increase
in machinability and since among the two, (Ti,Zr)4C2(S,Se,Te)2 especially deteriorates neither soft magnetic characteristics nor corrosion resistivity
and contributes to improvement on machinability without any loss of cold workability,
due to fine dispersion thereof, the elements are therefore added for the improvements.
Although the content of the elements singly or in combination is required to be 0.05
mass % of higher in terms of X in order to exert the effects, the soft magnetic characteristics
are degraded when the content in terms of X exceeds 0.5 mass % and accordingly, the
content is set to the range of 0.05 to 0.5 mass % in terms of X.
(30) C in the range of 0.02 X to 0.06 X mass %, 0.19 X to 0.26 X mass % or 0.02 X
to 0.26 X mass %
The reason why a C content is set to 0.02 X to 0.06 X mass % (0.02 ≤ C/X ≤ 0.06) or
0.19 X to 0.26 X mass % (0.19 ≤ C/X ≤ 0.26), wherein |α| ≤ 0.07, |α| being the absolute
value of α and this applying hereinafter, and α = Y/X - 32(C/X - 0.125)2 ( see Fig. 1), is that with such compositions adopted, in an electromagnetic stainless
steel, soft magnetic characteristics and cold workability are especially excellent,
machinability is also good due to dispersion in a fine particle state of (Ti,Zr)4C2(S,Se,Te)2 and (Ti,Zr)(S,Se,Te), the latter of which is formed in a small amount, and further,
corrosion resistivity is also good, wherein (Ti,Zr)4C2(S,Se,Te)2 has a little effect to degrade the soft magnetic characteristics. Excellence in the
soft magnetic characteristics in the region of this α is because of extremely low
level of the presence of (Ti,Zr)C, (Ti,Zr)(S,Se,Te) and Mn(S,Se,Te).
one or more of Ti and Zr in the range satisfying a relation of 0.05 ≤ X ≤ 3 (hereinafter referred to as a condition formula (1)),
one or more of S, Se and Te in the range satisfying a relation of 0.01 ≤ Y ≤ 0.5 X (hereinafter referred to as a condition formula (2)),
C in the range satisfying a relation of 0.2 Y ≤ WC ≤ 0.3 (hereinafter referred to as a condition formula (3)), wherein when a Ti content
is indicated by WTi in mass %, a Zr content by WZr in mass %, a C content by WC in mass %, a S content by WS mass %, a Se content by WSe and a Te content by WTe, the following formulae (1) and (2) are given in order to define X and Y:
(hereinafter referred to as Formula (1)) and
(hereinafter referred to as Formula (2)).
(31) 20 to 82 mass % Ni
A free cutting alloy of the fifth selection invention of the present invention includes
(Fe,Ni) based electromagnetic alloy and (Fe,Ni) based heat resisting alloy. Accordingly,
Ni is an indispensable element for the free cutting alloy of the fifth selection invention
of the present invention. Further, (Fe,Ni) based electromagnetic alloy and (Fe,Ni)
based heat resisting alloy are widely employed with content of the range of 20 to
82 mass % for Ni and since the alloys including Ni in content of this range are particularly
required improvement on machinability, the Ni content is limited to the range.
(32) one or more of Ti and Zr in content satisfying a relation of 0.05 ≤ X ≤ 3 (hereinafter
referred to as a condition formula (1))
When Ti and Zr are added in the above described range together with C, S, Se and Te,
(Ti,Zr) based compounds, for example, mainly (Ti,Zr)4(S,Se,Te)2C2 and/or a small amount of (Ti,Zr)(S,Se,Te), are formed and therefore, Ti and Zr are
useful for improvement on machinability. Moreover, since formation of (Mn,Cr,Ni)S,
especially NiS, is suppressed, Ti and Zr are also useful for prevention of cracking
in hot working and the free cutting alloy of the fifth selection invention can maintain
excellent characteristics as (Fe,Ni) based electromagnetic alloy or (Fe,Ni) based
heat resisting alloy such as a thermal expansion coefficient, an elastic constant,
magnetic characteristics or a high temperature strength. While Ti and Zr is required
to be included in the range of 0.05 mass % or higher in X of a compositional parameter
in order to attain an effect of improving machinability, X in excess of 3 mass % is
not preferable since when X is in excess of 3 mass %, a specific refining method is
required, being accompanied with poor productivity. Accordingly, the range of the
parameter X is preferably set in the range of 0.05 to 3 mass % and more preferably
in the range of 0.1 to 0.5 mass %. Further, when Ti and Zr are included in the range
satisfying the condition formula(1), either one of Ti and Zr or both Ti and Zr may
be included.
(33)
One or more of S, Se and Te in contents satisfying a relation of 0.01 ≤ Y ≤ 0.5 X
(hereinafter referred to as a condition formula (2))
S, Se and Te are indispensable elements for formation of the above described (Ti,
Zr) based compound. Therefore, the elements are indispensable components for improvement
on machinability and are required to be included in the range of 0.01 mass % or higher
in terms of the parameter Y. When the elements are added in excess, a compound not
useful for improving machinability is formed and in a case, performances of the alloy
are deteriorated. Therefore, when the parameters X and Y are related so as to satisfy
the above described condition formula (2), that is when the parameter Y corresponding
to a total number of S, Se and Te atoms is half the parameter X corresponding to a
total number of Ti and Zr atoms, an additive amount of one or more of S, Se and Te
is not excessive but falls within the proper range in amount and therefore, formation
of a compound not useful for improvement on machinability can be suppressed and deterioration
in performances of the alloy can be prevented or suppressed. As far as S, Se and Te
are included in the ranges to satisfy the condition formula (2), either only one of
them or two or more of them may be included in the alloy.
(34) C in content satisfying a relation of 0.2 Y ≤ Wc ≤ 0.3 (hereinafter referred
to as a condition formula (3))
C forms (Ti,Zr) based compound in co-existence with Ti and Zr, and S, Se and Te and,
it is an indispensable element for improvement on machinability. Moreover, C acts
usefully for prevention of cracking occurrence in hot workability. Especially, since
C accelerates formation of (Ti,Zr)4(S,Se,Te)2C2 more stable than (Ti,Zr)(S,Se,Te), improvement by C on machinability is more effective.
It is necessary to include C so as to satisfy the condition formula (3) for achievement
of the effects. That is, C is required to be included in the range of at least more
than 0.2 times the parameter Y(a parameter on which a total number of S, Se and Te
atoms is reflected). When a C content WC is WC < Y/5, the C content is excessively small, the effect of improving machinability
cannot be acquired. On the other hand, an excessive addition of C is not preferable
since such a C content causes deterioration in performances of Ni based electromagnetic
alloy and Ni based heat resisting alloy. Accordingly, the C content Wc is preferably
limited to 0.3 mass % or lower. When the C content exceeds 0.3 mass %, loss of performances
of Ni based alloy becomes large. The C content is desirably set in the range of Y/4
to 0.2 mass % and more desirably in the range of Y/4 to Y/2 mass %.
(35) 1 mass % or lower Si
Si is an element useful as a deoxidizing agent and in addition, for adjustment of
hardness and electric resistivity and accordingly, added depending on a necessity.
However, when an additive amount of Si is in excess, hardness after heat treatment
for solid solution is excessively high, which disadvantageously brings poor workability.
Characteristics such as thermal expansion, an elastic constant, magnetic characteristics,
heat resistance (high temperature strength) and the like are degraded in some cases.
Accordingly, the Si content is limited to 1 mass % as the upper limit and when cold
workability is regarded as an important requirement, the Si content is preferably
set to 0.5 mass % or lower.
(36) 1 mass % or lower Mn
Mn is an element useful as an deoxidizing agent and further, since Mn forms a compound
excellent in machinability in co-existence with S and Se, Mn is added to alloy according
to a requirement especially when machinability is regarded as important. The Mn content
is desirably set to 0.1 mass % or higher in order to attain more conspicuousness of
the effect. On the other hand, when added in excess, corrosion resistivity and cold
workability are degraded and deterioration sometimes occurs in characteristics such
as thermal expansion, an elastic constant, magnetic characteristics, heat resistivity
(high temperature strength) and the like as well. Accordingly, the Mn content is preferably
limited to 1 mass % or lower and more desirably to 0.5 mass % or lower.
(37) 1 mass % or lower Al
Al is an element useful as a deoxidizing agent and added to alloy in necessary since
Al is effective for adjustment for hardness and electric resistivity. However, when
added in excess, deterioration sometimes occurs in characteristics such as thermal
expansion, an elastic constant, magnetic characteristics, heat resistivity (high temperature
strength) and the like. Accordingly, the A1 content is limited to 1 mass % or lower.
(38) 7 mass % or lower Mo
Mo is an element useful for improvement on corrosion resistivity and strength. When
the effects are desired to be conspicuous, Mo is preferably included in the range
of 0.2 mass % or higher. On the other hand, when added in excess, not only is hot
workability deteriorated, but cost-up also occurs and furthermore, deterioration sometimes
occurs in characteristics such as thermal expansion, an elastic constant, magnetic
characteristics, heat resistivity (high temperature strength) and the like. Accordingly,
the Mo content is preferably limited to 1 mass % or lower and more desirably to 0.7
mass % or lower.
(39) 7 mass % or lower Cu
C is not only useful for improvement on corrosion resistivity, especially in an environment
of a reducing acid, but effective for improvement on moldability, decreasing work
hardenability. Moreover, since an antibacterial property can also be improved by heat
treatment or the like processing, Cu may be added to the alloy according to a necessity.
However, since when added in excess, hot workability decreases, the Cu content is
preferably set to 7 mass % or lower and especially when hot workability is regarded
as important, the Cu content is desirably suppressed to 4 mass % or lower.
(1) High permeability materials including 78-Permalloy, 45-Permalloy, Hipernik, Monimax, Sinimax, Radiometal, 1040 Alloy, Mumetal, Cr-Permalloy, Mo-Permalloy, Supermalloy, Hardperm, 36-Permalloy and Deltamax;
(2) Iso-permeability alloy including 25-45 Perminvar, 7-70 Perminvar, 7-25-45 Perminvar, Isoperm and Senperm;
(3) Invar alloy including Invar, Superinvar, Stainlessinvar, Nobinite alloy and LEX alloy;
(4) Elinvar alloy including Elinvar, EL-1, EL-3, Iso-elastic, Metelinvar, Elinvar Extra, Ni-Span C-902, Y Nic, Vibralloy, Nivarox CT, Durinval I, Co-Elinvar and Elcoloy IV;
(5) Fe based super heat resisting alloy including Haynes 556, Incoloy 802, S-590, 16-25-6 and 20-CB3; and
(6) Ni based heat resisting alloy including Hastelloy-C22, Hastelloy-C276, Hastelloy-G30, Hasteolloy X, Inconel 600 and KSN.
Examples
Example 1 Ferrite containing stainless steel
Table 1
1) Hot workability test
Evaluation of hot workability was effected based on visual observation of whether
or not defects such as cracks occur in hot forging. [○] indicates that substantially
no defect occurred in hot forging, [×] indicates that large scale cracks were recognized
in hot forging and Δ indicates that small cracks occurred in hot forging.
2) Evaluation of machinability
Evaluation of machinability was collectively effected based on cutting resistance
in machining, finished surface roughness and chip shapes. A cutting tool made of cermet
was used to perform machining under a dry condition at a circumferential speed of
150 m/min, a depth of cutting per revolution of 0.1 mm and a feed rate per revolution
of 0.05 mm. A cutting resistance in N as a unit was determined by measuring a cutting
force generating in the machining. The finished surface roughness was measured by
a method stipulated in JIS B 0601 and a value thereof was an arithmetic average roughness
(in µm Ra) on a test piece surface after the machining. Moreover, chip shapes were
visually observed and when friability was good, the result is indicated by [G] and
when friability is bad and all chips are not separated but partly connected, the result
is indicated by [B] and when evaluation of chip shapes is intermidiate of [G] and
[B], the result is indicated by [I].
3)
4)Evaluation of out-gas resistivity
Evaluation of out-gas resistivity was performed by determining an amount of released S. To be concrete,
test pieces in use each had the shape of a rectangular prism of 15 mm in length, 25
mm in width and 3 mm in thickness and the entire surface of each were polished with
No. 400 emery paper. A test piece was placed in a sealed vessel having an inner volume
of 250 cc together with a silver foil having a size of 10 mm in length, 5 mm in width
and 0.1 mm in thickness and 0.5cc of pure water, and a temperature in the vessel was
maintained at 85°C for 20 hr. A S content Wso in the silver foil after the process
for the test was measured by a combustion type infrared absorbing analysis method.
4) Cold workability test
Evaluation of cold workability was performed by measuring a threshold compressive
stain in a compression test on specimens Nos. 1 to 5 and 13. Test pieces for compression
each had the shape of a cylinder of 15 mm in diameter and 22.5 mm in height and each
piece was compressed by a 600 t oil hydraulic press to obtain a threshold compressive
strain, wherein the threshold compressive strain is defined as ln (H0/H) or a natural
logarithm of H0/H, H0 being an initial height of the test piece and H being a threshold
height which is a maximum height at which no cracking has occurred. First selection
inventive alloys of the specimens Nos. 1 to 5 were confirmed to have high threshold
compressive ratios almost equal to comparative steel specimen No. 15 and higher than
comparative steel specimen No. 16 by about 20 %, and have a good cold workability
as well.
5) Evaluation of corrosion resistivity
Evaluation of corrosion resistivity was performed by a salt spray test. Test pieces
each were prepared so to have the shape of a cylinder of 10 mm in diameter and 50
mm in height. The entire surface of each test piece was polished with No. 400 emery
paper and cleaned. A test piece was exposed to a fog atmosphere of 5 mass % NaCl aqueous
solution at 35°C for 96 hr. Final evaluation was visually performed with the naked
eye. As a result, the inventive steel of the present invention was confirmed to maintain
good corrosion resistivity. The results are shown in Table 2.
Table 2
Example 2 Martensite containing stainless steel
Table 3
1) Hot workability test
Evaluation of hot workability was effected based on visual observation of whether
or not defects such as cracks occur in hot forging. While workability in hot forging
was at levels at which processing can be performed with no problem, as not only inclusions
but an amount of alloy elements increase, deterioration in the workability was a tendency
observed in the test. It was found that kinds of steel of the present invention in
which one or more of Ca, B, Mg and REM was included had good hot workability when
comparing with a kind of steel in which none of the elements was included.
2) Evaluation of machinability
Evaluation of machinability was collectively effected based on tool ware loss in machining,
finished surface roughness and ship shapes. A cutting tool made of cermet was used
to perform machining under a wet condition by water-soluble cutting oil at a circumferential
speed of 120 m/min, a depth of cutting per revolution of 0.1 mm and a feed rate per
revolution of 0.05 mm. The tool ware loss was measured at a flank of the cutting tool
after 60 min machining with µm as a unit of the tool wear loss. The finished surface
roughness and chip shapes were evaluated by a method similar to that in Example 1.
The following evaluations were performed using material subjected to treatments in
which the material is kept at 980 to 1050°C for 30 min, thereafter subjected to a
quenching heat treatment and still further subjected to a tempering treatment of holding
at 180°C for 1 hr, followed by air cooling.
3) Hardness test
Measurement of hardness on a test piece was performed on a C scale Rockwell hardness
by the Rockwell hardness test stipulated in JIS Z 2245. The Rockwell hardness was
obtained as the average of measurements at arbitrary 5 measuring points S on a circle
drawn on a cross section of a rod test piece having a circular section, the circle
drawn on the cross section being a circle satisfying a relation of PS = 0.25 PG, wherein
G denotes a point almost coinciding with a center of the circular section, P denotes
an arbitrary point on the outer periphery of the test piece and a point S is on a
line segment PG
4) Evaluation of out-gas resistivity
Evaluation of out-gas resistivity was performed similar to in Example 1.
5) Evaluation of corrosion resistivity
Evaluation of corrosion resistivity was performed by a method similar to in Example
1. Test pieces each were prepared so to have the shape of a cylinder of 15 mm in diameter
and 50 mm in height. The entire surface of each test piece was polished. Each test
piece was polished and thereafter, a test piece was held in a thermohygrostat at a
temperature of 60°C and a relative humidity of 90 % RH for 168 hr. An evaluation method
was such that when no rust was confirmed, the test piece was evaluated [A], when dot-like
stains were recognized at several points on a test piece, the test piece was evaluated
[B], when red rust was recognized in an area of an area ratio of 5 % or less, the
test piece was evaluated [C] and when red rust was recognized in an area wider than
an area ratio of 5 %, the test piece was evaluated [D]. The results are shown in Table
4.
Table 4
Example 3 Austenite containing stainless steel
Table 5
Table 6
Example 4 Electromagnetic stainless steel
Table 7
Table 8
Measuring methods
1) Magnetic characteristics
A test piece in the shape of a ring, of 10 mm in outer diameter, 5 mm in inner diameter
and 5 mm in thickness was prepared for measurement of magnetic characteristics. The
test piece received magnetic annealing at 950°C and thereafter, direct current magnetic
characteristics including a magnetic flux density and a direct current coercive force
were measured by a B-H loop tracer: a magnetic flux density B1 (KG) under a magnetic
field of 1 Oe and a magnetic flux density B10 (KG) under a magnetic field of 10 Oe
and a direct current coercive force Hc (A/cm). Relations between a magnetic flux density
B1 or a coercive force Nc and α are shown in Fig. 10.
2) Electric resistivity
Electric resistivity was measured on test pieces, which were each prepared by subjecting
a test rod to cold wire-drawing to obtain a wire of 1 mm in diameter, and then performing
vacuum annealing at 950°C thereon.
3) Machinability
Machinability was evaluated as follows: a SKH 51 drill of 5 mm in diameter was used
on a test piece of steel for machining at a number of revolution of 915 rpm under
a load of 415 N on a cutting edge thereof and a time in sec consumed for boring a
hole of 10 mm in depth was measured. Machinability was evaluated by a length of the
time in sec.
4) Cold workability
Cold workability was evaluated by a cracking threshold working ratio and a procedure
was as follows: a test piece was prepared in the shape of a cylinder, 20 mm in diameter
and 30 mm in height. The test piece was annealed at 720°C and thereafter a compression
test was performed on the test piece under a hydraulic pressure of 400 t to evaluate
a cracking threshold working ratio. Relations of a boring time or a cracking threshold
working ratio and α are shown in Fig. 11.
5) Pitting potential
A test piece was prepared in the shape of a disc whose size is 18 mm in diameter and
2 mm in thickness. The test piece was polished with sand papers up to No. 800 and
subjected to magnetic annealing at 950° for 2 hr in a vacuum. Thereafter, a pitting
potential Vc in mV was measured on the test piece in a 3.5 % NaCl aqueous solution
at 30°C. Fig. 12 shows a relation between a pitting potential and α. The measuring
results are shown in Tables 9 and 10.
Table 9
Table 10
Example 5 (Fe,Ni) based alloy
Table 11
Table 12
Table 13
1) Hot workability test
Evaluation of hot workability was effected based on visual observation of whether
or not defects such as cracks occur in hot forging. [○] indicates that substantially
no defect occurred in hot forging, [×] indicates that large scale cracks were recognized
in hot forging and Δ indicates that so small cracks as to be removed by a grinder
occurred in hot forging. A relation between the ranges of the parameters of X and
Y defined by the formulae (1) and (2) and evaluation results of hot workability is
shown in Fig. 15.
2) Machinability Machinability was evaluated as follows: a SKH 51 drill of 5 mm in diameter was used on a test piece of steel for machining at a number of revolution of 915 rpm under a load of 415 N on a cutting edge thereof and a time in sec consumed for boring a hole of 10 mm in depth on steel was measured. Machinability was evaluated by a length of the time. A relation between a parameter Y in mass % and a boring time is shown Fig. 16.
3) Magnetic characteristics
Test pieces each in the shape of a ring, of 10 mm in outer diameter, 4.5 mm in inner
diameter and 5 mm in thickness were prepared for measurement of magnetic characteristics.
A test piece received magnetic annealing at 1000°C and thereafter, direct current
magnetic characteristics including a magnetic flux density, a maximum magnetic permeability
and a direct current coercive force were measured by a B-H loop tracer: a magnetic
flux density B1 (T) under a magnetic field of 1 Oe, a magnetic flux density B5 (T)
under a magnetic field of 5 Oe, and a magnetic flux density B10 (T) under a magnetic
field of 10 Oe, a maximum magnetic permeability(µm) and a direct current coercive
force Hc (A/cm).
4) An evaluation for thermal expansion coefficient and temperature coefficient of
Young's modulus
An evaluation for thermal expansion coefficient was performed on the test alloy pieces
which were each shaped into a cylinder of 5 mm in diameter and 50 mm in height. The
thermal expansion coefficient was measured at temperatures ranging from 0 to 80°C,
after the pieces were annealed at 830°C. For measurement of temperature coefficient
of Young's modulus, test alloy pieces were each shaped into a cylinder of 5 mm in
diameter and 80 mm in height and thereafter, processed in a solution treatment at
1000°C, followed by rapid cooling. After the rapid cooling, an alloy cylinder as an
intermediate was subjected to an aging heat treatment at temperatures from 580 to
590°C into a final test alloy piece. Young's modulus was measured on the test alloy
pieces at temperatures ranging from 20 to 100°C using a free resonance elastic modulus
tester. The results are shown in Tables 14 and 15.
Table 14
Table 15
(hot warkability) | (machinability) boring time (sec) | thermal expansion coefficient (×10-7/K) | temperature coefficient of Young' s modulus (10-5/K) | magnetic characteristics | remark | |||||
B1 (T) | B5 (T) | B10 (T) | µm (T) | Hc (A/cm) | ||||||
41 | ○ | 24.4 | - | - | - | - | - | 121,000 | 0.013 | fifth selection inventive alloy |
42 | ○ | 13.2 | - | - | - | - | 112,000 | 0.017 | ||
43 | ○ | 27.9 | - | - | - | - | - | 120,000 | 0.014 | |
44 | ○ | 26.8 | - | - | - | - | - | - | - | |
45 | ○ | 12.6 | - | - | - | - | - | - | - | |
46 | ○ | 13.3 | - | - | - | - | - | - | - | |
47 | ○ | 13.2 | - | - | - | - | - | - | - | |
48 | ○ | 10.2 | - | - | - | - | - | - | - | |
49 | ○ | 12.5 | - | - | - | - | - | - | - | |
50 | ○ | 10.8 | - | - | - | - | - | - | - | |
51 | ○ | 15.9 | - | - | - | - | - | - | - | |
52 | ○ | 11.3 | - | - | - | - | - | - | - | |
53 | ○ | 22.3 | - | - | - | - | - | - | - | |
54 | ○ | 23.1 | - | - | - | - | - | - | - | |
55 | ○ | 18.3 | - | - | - | - | - | - | - | |
56 | ○ | 17.6 | - | - | - | - | - | - | - | |
57 | ○ | 20.6 | - | - | - | - | - | - | - | |
58 | ○ | 15.1 | - | - | - | - | - | - | - | |
59 | ○ | 27.4 | 7.76 | - | - | - | - | - | - | comparative alloy |
60 | ○ | 25.8 | - | - | 1.13 | 1.35 | 1.42 | 28,300 | 0.12 | |
61 | ○ | 27.6 | - | ±1 | - | - | - | - | - | |
62 | ○ | 19.1 | 4.21 | - | - | - | - | - | - | |
63 | ○ | 33.8 | - | - | - | - | - | 12,600 | 0.013 | |
64 | ○ | 20.8 | - | - | - | - | - | - | - | |
65 | ○ | 25.4 | - | - | - | - | - | - | - | |
66 | × | - | - | - | - | - | - | - | - | |
67 | × | - | - | - | - | - | - | - | - | |
68 | × | - | - | - | - | - | - | - | - | |
69 | × | - | - | - | - | - | - | - | - | |
70 | × | - | - | - | - | - | - | - | - | |
71 | Δ | 11.8 | - | - | - | - | - | - | - | inventive alloy |
72 | Δ | 12.7 | - | - | - | - | - | - | - | |
73 | Δ | 15.3 | - | - | - | - | - | - | - | |
74 | Δ | 16.8 | - | - | - | - | - | - | - | |
75 | Δ | 12.9 | - | - | - | - | - | - | - |
1. Free cutting alloy wherein a (Ti,Zr) based compound is formed in a matrix metal phase, and said (Ti,Zr) based compound contains one or more of Ti and Zr as a metal element component, C being an indispensable element as a bonding component with the metal element component, and one or more of S, Se and Te.
2. Free cutting alloy according to aspect 1, wherein said (Ti,Zr) based compound is formed in a dispersed state in said matrix metal phase.
3. Free cutting alloy according to aspect 1 or 2, wherein said (Ti,Zr) based compound contains at least a compound expressed in a composition formula (Ti,Zr)4(S,Se,Te)2C2.
4. Free cutting alloy according to any of aspects 1 to 3, containing one or more of Ti and Zr such that WTi + 0.52 WZr = 0.03 to 3.5 mass %, wherein WTi and WZr denote respective contents in mass % of Ti and Zr; and one or more of S and Se in the respective ranges of 0.01 to 1 mass % for S and 0.01 to 0.8 mass % for Se.
5. Free cutting alloy according to aspect 4, constituted as ferrite containing stainless steel containing: 2 mass % or lower, including zero, Ni; 12 to 35 mass % Cr; and 0.005 to 0.4 mass % C.
6. Free cutting alloy according to aspect 4, constituted as martensite containing
stainless steel containing: 2 mass % or lower, including zero, Ni; 9 to 17 mass %
Cr; and C satisfying the following formulae:
and
wherein WTi, WZr WC, WS and WSe denote respective contents of Ti, Zr, C, S and Se, all in mass %.
7. Free cutting alloy according to aspect 5 or 6, containing 2 mass % or lower, including zero Si; 2 mass % or lower, including zero Mn; 2 mass % or lower, including zero Cu; and 2 mass % or lower, including zero Co.
8. Free cutting alloy according to any of aspects 5 to 7, containing one or more of Mo and W in the respective ranges of 0.1 to 4 mass % for Mo and 0.1 to 3 mass % for W.
9. Free cutting alloy according toaspect 4,constituted as austenite containing stainless steel containing: 2 to 50 mass % Ni; 12 to 50 mass % Cr; 5 to 85.95 mass % Fe; and 0.01 to 0.4 mass % C.
10. Free cutting alloy according to aspect 9, containing: 4 mass % or lower, including zero Si; 4 mass % or lower, including zero Mn; 4 mass % or lower, including zero Cu; and 4 mass % or lower, including zero Co.
11. Free cutting alloy according to aspect 9 or 10, containing one or more of Mo and W in the respective ranges of 0.1 to 10 mass % for Mo and 0.1 to 10 mass % for W.
12. Free cutting alloy according to any of aspects 5 to 11, containing: 0.05 mass % or lower, including zero P; and 0.03 mass % or lower, including zero O; and 0.05 mass % or lower, including zero N.
13. Free cutting alloy according to any of aspects 5 to 12, containing one or more of Te, Bi and Pb in the respective ranges of 0.005 to 0.1 mass % for Te; 0.01 to 0.2 mass % for Bi; and 0.01 to 0.3 mass % for Pb.
14. Free cutting alloy according to any of aspects 5 to 13, containing one or more selected from the group consisting of Ca, Mg, B and REM (one or more of metal elements classified as Group 3A in the periodic table of elements) in the range of 0.0005 to 0.01 mass % for one element or as a total content of more than one elements combined.
15. Free cutting alloy according to any of aspects 5 to 14, containing one or more selected from the group consisting of Nb, V, Ta and Hf in each range of 0.01 to 0.5 mass %.
16. Free cutting alloy according to any of aspects 5 to 15, the Wso value of which is less than 0.035 mass % when the following test is performed:
an alloy test piece of said free cutting alloy is prepared so as to have the shape of rectangular prism in size of 15 mm in length, 25 mm in width and 3 mm in thickness with the entire surface being polished with No. 400 emery paper;
a silver foil in size of 10 mm in length, 5 mm in width and 0.1 mm in thickness with a purity of 99.9 % or higher as a S getter; 0.5 cc of pure water are sealed in a vessel of an inner volume of 250 cc together with said test piece;
the temperature in said vessel is raised to 85°C and said temperature is then kept there for 20 hr;
and thereafter, the S content in mass % in said silver foil piece is analyzed, then S content obtained is defined as said Wso.
17. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.06 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z - 0.07)X to (Z + 0.07)X mass %, wherein X, Z and Y are values of
the respective following formulae 1, 3 and 2; and the balance being Fe and inevitable
impurities:
and
18. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.06 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z - 0.07)X to (Z + 0.07)X mass %, wherein X, Z and Y are values of
the respective following formulae 1, 3 and 2; and furthermore, one or more selected
from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass
% or lower for Ni; 2 mass % or lower for Cu; 2 mass % or lower for Mo; 1 mass % or
lower for Nb; and 1 mass % or lower for V; and the balance being Fe and inevitable
impurities:
and
19. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % A1; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.06 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z - 0.07)X to (Z + 0.07)X mass %, wherein X, Z and Y are values of
the respective following formulae 1, 3 and 2; and furthermore, one or more of Pb,
B and REM in the respective ranges of 0.15 mass % or lower for Pb; 0.01 mass % or
lower for B; and 0.1 mass % or lower for REM; and the balance being Fe and inevitable
impurities:
and
20. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.06 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z - 0.07)X to (Z + 0.07)X mass %, wherein X, Z and Y are values of
the respective following formulae 1, 3 and 2, furthermore, one or more selected from
the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass %
or lower for Ni; 2 mass % or lower for Cu; 2 mass % or lower for Mo; 1 mass % or lower
for Nb and 1 mass % or lower for V; and furthermore, one or more of Pb, B and REM
in the respective ranges of 0.15 mass % or lower for Pb; 0.01 mass % or lower for
B; and 0.1 mass % or lower for REM; and the balance being Fe and inevitable impurities:
and
21. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.19 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z - 0.07)X to (Z + 0.07)X mass %, wherein X, Z and Y are values of
the respective following formulae 1, 3 and 2 and the balance being Fe and inevitable
impurities:
and
22. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.19 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z - 0.07)X to (Z + 0.07)X mass %, wherein X, Z and Y are values of
the respective following formulae 1, 3 and 2; and furthermore, one or more selected
from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass
% or lower for Ni; 2 mass % or lower for Cu; 2 mass % or lower for Mo; 1 mass % or
lower for Nb and 1 mass % or lower for V and the balance being Fe and inevitable impurities:
and
23. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.19 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z - 0.07)X to (Z + 0.07)X mass %, wherein X, Z and Y are values of
the respective following formulae 1, 3 and 2; and furthermore, one or more of Pb,
B and REM in the respective ranges of 0.15 mass % or lower for Pb; 0.01 mass % or
lower for B; and 0.1 mass % or lower for REM; and the balance being Fe and inevitable
impurities:
and
24. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.19 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z - 0.07)X to (Z + 0.07)X mass %, wherein X, Z and Y are values of
the respective following formulae 1, 3 and 2, furthermore, one or more selected from
the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass %
or lower for Ni; 2 mass % or lower for Cu; 2 mass % or lower for Mo; 1 mass % or lower
for Nb and 1 mass % or lower for V; and furthermore, one or more of Pb, B and REM
in the respective ranges of 0.15 mass % or lower for Pb; 0.01 mass % or lower for
B; and 0.1 mass % or lower for REM; and the balance being Fe and inevitable impurities:
and
25. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z + 0.07)X to (Z + 0.45) X, the lower limit not included, mass %,
wherein X, Z and Y are values of the respective following formulae 1, 3 and 2; and
the balance being Fe and inevitable impurities:
and
26. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z + 0.07)X to (Z + 0.45) X, the lower limit not included, mass %,
wherein X, Z and Y are values of the respective following formulae 1, 3 and 2; and
furthermore, one or more selected from the group consisting of Ni, Cu, Mo, Nb and
V in the respective ranges of 2 mass % or lower for Ni; 2 mass % or lower for Cu;
2 mass % or lower for Mo; 1 mass % or lower for Nb and 1 mass % or lower for V; and
the balance being Fe and inevitable impurities :
and
27. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z + 0.07)X to (Z + 0.45) X, the lower limit not included, mass %,
wherein X, Z and Y are values of the respective following formulae 1, 3 and 2; and
furthermore, one or more of Pb, B and REM in the respective ranges of 0.15 mass %
or lower for Pb; 0.01 mass % or lower for B; and 0.1 mass % or lower for REM; and
the balance being Fe and inevitable impurities:
and
28. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Or; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z + 0.07)X to (Z + 0.45) X, the lower limit not included, mass %,
wherein X, Z and Y are values of the respective following formulae 1, 3 and 2; furthermore,
one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective
ranges of 2 mass % or lower for Ni; 2 mass % or lower for Cu; 2 mass % or lower for
Mo; 1 mass % or lower for Nb and 1 mass % or lower for V; and furthermore, one or
more of Pb, B and REM in the respective ranges of 0.15 mass % or lower for Pb; 0.01
mass % or lower for B; and 0.1 mass % or lower for REM; and the balance being Fe and
inevitable impurities:
and
29. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z + 0.45)X to (Z + 0.70)X, the lower limit not included, mass %,
wherein X, Z and Y are values of the respective following formulae 1, 3 and 2; and
the balance being Fe and inevitable impurities:
and
30. Free cutting alloy according to any of aspects 1 to 3, constituted as electromagnetic
stainless steel containing: 0.01 to 3 mass % Si; 2 mass % or lower Mn; 5 to 25 mass
% Cr; 0.01 to 5 mass % Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass
% in terms of X of the following formula 1; C in the range of 0.02 X to 0.26 X mass
%, wherein X is expressed by the following formula 1; one or more of S, Se and Te
in the range of (Z + 0.45)X to (Z + 0.70)X, the lower limit not included, mass %,
wherein X, Z and Y are values of the respective following formulae 1, 3 and 2; and
furthermore, one or more selected from the group consisting of Ni, Cu, Mo, Nb and
V in the respective ranges of 2 mass % or lower for Ni; 2 mass % or lower for Cu;
2 mass % or lower for Mo; 1 mass % or lower for Nb and 1 mass % or lower for V; and
the balance being Fe and inevitable impurities:
and
31. Free cutting alloy according to any of aspects 1 to 3, containing:
20 to 82 mass % Ni; and the balance mainly consists of one or more of Fe and Cr; further containing:
one or more of Ti and Zr in the range satisfying a relation of 0.05 ≤ X ≤ 3;
one or more of S, Se and Te in the range satisfying a relation of 0.01 ≤ Y ≤ 0.5 X;
C in the range satisfying a relation of 0.2 Y ≤ WC ≤ 0.3, wherein when a Ti content is indicated by WTi in mass %, a Zr content by WZr in mass %, a C content by WC in mass %, a S content by WS in a mass %, a Se content by WSe in a mass % and a Te content by WTe in a mass %, the following formulae are given in order to define X and Y:
and
and one or more of Si, Mn and Al in the respective ranges of 1 mass % for Si; 1 mass
% for Mn; and 1 mass % for Al.
32. Free cutting alloy according to aspect 31, containing: one or more of Mo and Cu in the respective ranges of 7 mass % or lower for Mo and 7 mass % or lower for Cu.
33. Free cutting alloy according to aspect 31 or 32, containing:12 mass % or lower Cr.
34. Free cutting alloy according to any of aspects 31 to 33, containing:18 mass % or lower Co.
one or more of Ti and Zr in the range satisfying a relation of 0.05 ≤ X ≤ 3;
one or more of S, Se and Te in the range satisfying a relation of 0.01 ≤ Y ≤ 0.5 X;
C in the range satisfying a relation of 0.2 Y ≤ WC ≤ 0.3, wherein when a Ti content is indicated by WTi in mass %, a Zr content by WZr in mass %, a C content by WC in mass %, a S content by WS in a mass %, a Se content by WSe in a mass % and a Te content by WTe in a mass %, the following formulae are given in order to define X and Y:
and
and
one or more of Si, Mn and Al in the respective ranges of 1 mass % for Si; 1 mass % for Mn; and 1 mass % for Al; and wherein a (Ti, Zr) based compound containing one or more of Ti and Zr as a metal element component, C being an indispensable element as a bonding component with the metal element component, and one or more of S, Se and Te is dispersed in a matrix metal phase.