Detailed description
[0001] The invention relates to a material comprising an iron based alloy containing C,
B, Cr, Ni, Si and Mo.
[0002] The material or alloy may be used for producing formed products, casted products,
coatings, parts, coated parts, wires, electrodes, powders and powder mixtures.
Prior Art
[0003] There is a need in industry for an alloy material which has excellent resistance
agains wear and corrosion and a low cost.
[0004] The use of nickel-based alloys with additions of chromium and molybdenum to give
protection from wear and corrosion has long been known. Such alloys are disclosed
for example in the patents
US 6,027,583 A,
US 6,187,115 A and
US 6,322,857 A.
[0005] EP 1 788 104 A1 discloses a material for producing parts or coatings adapted for high wear and friction-intensive
applications. The material comprises a nickel based alloy with the addition of hard
particles such as WC.
[0006] The elements Ni and W are expensive and alternatives are sought.
[0007] Iron-based self-fluxing alloys are an alternative group of lower cost materials and
many materials have been found that exhibit reasonable wear resistance.
[0008] Such an iron-based alloy is known from
DE 197 33 306 C1. It discloses an iron-based thermal coating material. The alloy is used as additive
material, in the form of a mixture, a gas atomized alloy, an agglomerated metal powder,
a core-filled wire, a core-filled strip, a sintered strip or a cast sheathed rod electrode
and used for thermal coating of components exposed to friction. A preferred composition
of the alloy for applying a low friction and low wear layer for a sliding component
pairing with good fatigue and impact resistance is as follows (by weight): 20-25%
Mn, 13-20% Cr, 0.1-2% Ni, 3-6% W, 0.1-0.15% C, 1.5-2.5% B, balance Fe. Another preferred
composition of the alloy for applying a low friction layer with high abrasion resistance
and higher thermal loading capacity is as follows (by weight): 18-25% Mn, 13-25% Cr,
0.1-2% Ni, 3-5% W, 0.1-0.15% C, 4-6% B, balance Fe.
[0009] DE 199 01 170 A1 discloses another iron alloy with high carbon, boron, vanadium, chromium, molybdenum
and nickel contents. The following composition is proposed (by weight): 2.0-4.0 %
C, 2.0-4.5 % B, 0.5-3.5 % Si, 6.0-15.0 % Cr, 1.5-7.5 % Mo, 6.0-14.0 % V, 0-3.0 % W,
0-1.5 % Mn, 0-2.0 % Cu, 2.0-7.0 % Ni, balance Fe and impurities. The alloy is used
for internal hard facing of metal cylinders by centrifugal casting or hot isostatic
pressing.
[0010] CA 2 416 950 A1 discloses a material for the manufacture of parts and tools for use at elevated temperature,
comprising an iron-based alloy comprising C, Si, Mn, Cr, Ni and N in certain concentrations.
The alloy is cold formed to a hardness of at least 230 HB.
[0011] However, there remain two problems with such Fe-based alloys. First, the wear resistance
of these Fe-based alloys is still inferior to Ni-based alloys with WC. To get close
to those properties, the base alloy must use expensive alloying elements such as W,
Nb or add large quantities of WC particles. These alloying elements increase the price
and make the material very hard (more than 65 HRC), which poses additional processing
and application problems with cracking. Secondly, the Fe-based materials do not have
a good corrosion resistance, like that of Ni based alloys, particularly in mixed corrosion
environments.
Object of the invention
[0012] It is therefore an object of the invention to provide an alternative material of
lower cost that is suitable to produce parts or coatings having a high wear and also
high chemical resistance.
[0013] The object is achieved by a material comprising an alloy containing 13 to 16 percent
by weight nickel (Ni), 13.5 to 16.5 percent by weight of chromium (Cr), 0.5 to 3 percent
by weight of molybdenum (Mo), 3.5 to 4.5 percent by weight of silicon (Si), 3.5 to
4 percent by weight of boron (B), 1.5 to 2.1 percent by weight of carbon (C) and 0.2
to 0.5 percent by weight of copper (Cu), and optionally may contain 0.2-0.5 percent
copper and less than 1 percent vanadium, balance iron (Fe).
[0014] It was found that such iron based alloys with C, B, Cr, Ni, Si and Mo exhibit high
wear and surprisingly high chemical resistance.
[0015] The material comprises an iron based alloy with the further components C, B, Cr,
Ni, Si and Mo. The material includes the pure alloy and coatings with a composition
of the alloy.
[0016] The alloy contains only C, B, Cr, Ni, Si and Mo as major components besides the main
component Fe, and optionally it may contain copper and vanadium. Generally the alloy
contains traces or minor amounts of other elements, which are generally common impurities.
[0017] The alloy is useful for producing either coatings on a metal substrate or for producing
formed products, casted products, coatings, parts, coated parts, wires, electrodes
or powders.
[0018] In general the alloy consists of 13 to 16 percent by weight (wt.-%) nickel (Ni),
13.5 to 16.5 percent by weight of chromium (Cr), 0.5 to 3 percent by weight of molybdenum
(Mo), 3.5 to 4.5 percent by weight of silicon (Si), 3.5 to 4 percent by weight of
boron (B) and 1.5 to 2.1 percent by weight of carbon (C), balance iron (Fe) and possible
impurities.
[0019] Impurities are normally present and are generally unavoidable. The content of impurities
in the alloy is generally less than 1 percent by weight, preferably less than 0.5
percent by weight and most preferred less than 0.2 percent by weight. All weight percentages
mentioned are based on the weight of the total composition, which is 100 percent by
weight.
[0020] A preferred composition of the alloy is 13 to 14 percent by weight of nickel (Ni),
14 to 16 percent by weight of chromium (Cr), 1 to 3 percent by weight of molybdenum
(Mo), 3.5 to 4.5 percent by weight of silicon (Si), 3.5 to 4 percent by weight of
boron (B), 1.8 to 2.1 percent by weight of carbon (C) and 0.2 to 0.5 percent by weight
of copper (Cu), balance iron (Fe) and possible impurities.
[0021] The alloy has an unusual good corrosion resistance in mixed corrosion conditions
where most Ni-based or Fe-based wear resistant materials do not satisfy. It is remarkable
that the Fe-based alloy contains no addition of other hard particles to increase its
hardness, such as Tungsten Carbide (WC).
[0022] Generally the alloys have a hardness in the range of 35 HRC to 60 HRC, particularly
in the range of 55 HRC to 60 HRC, typically around 58 HRC, which is unusually low
for such a wear resistant material. It gives an advantage In processing and operation
as it makes the alloy less sensitive to cracking.
[0023] Here, the unit "HR" represents the so called "Rockwell hardness". There are several
Rockwell scales for different ranges of hardness. The most common are the B scale
(HRB), which is appropriate for soft metals, and the C scale (HRC) for hard metals.
The method for measuring hardness according to Rockwell is specified in DIN EN ISO
6508- ASTM E-18. Rockwell hardness numbers are not proportional to Vickers hardness
readings, but there exist conversion tables, according to which the above range of
35 to 60 HRC is corresponding a Vickers hardness of between 345 and 780 HV/10.
[0024] The alloys generally have a melting point in the range of 1.000 to 1.150° C, typically
around 1080° C. This a very low melting temperature for such an alloy with these properties,
which reduces costs in processing and gives application advantages.
[0025] The alloy is produced in the conventional manner by melting of the components or
blending of powders or compounds.
[0026] The alloy can be cast to products of any shape.
[0027] The alloy is used for the production of parts or coatings on parts, which are generally
metal substrates or metal parts, especially made of steel. Metal parts are e.g. rotors,
sleeves, bearings, screws, blades, etc.
[0028] The material, in particular the alloy, is preferably used for the production of wires,
filling wires, bands, strand-shaped products, electrodes, powders, pastes, slurries,
or cast bar material, which are used e.g. for casting, welding, plasma transferred
arc welding (PTA), plasma powder build-up welding or arc welding, brazing, flame spraying,
in particular high-speed flame spraying (HVOF), sinter fusing and similar processes.
[0029] The invention also comprises a process for applying a material according to the invention
for the production of coatings with a high level of resistance to corrosion and wear
on a workpiece by a thermal coating process, in which the coating material in powder
form is alloyed and atomized from the melt or agglomerated from various alloyed and
non-alloyed metal powders.
[0030] The coatings or protective layers of the alloy on parts, in particular metal parts,
are produced preferably by conventional methods of applying a powder by pouring, casting,
dipping, spraying, spinning followed by a thermal fusion treatment or by thermal methods
like flame spraying, and preferably by high velocity flame spraying (HVOF), or by
plasma transferred are welding. Such coating methods are described, for example, in
US 6,187,115 A and
US 6,322,857 A, which can be applied analogously and which are incorporated by reference.
[0031] Such coatings can be produced as mentioned above in the thermal processes by using
materials containing the alloy, like powders, wires, electrodes or other conventional
forms, or by applying two or more materials, which deviate in the composition from
the resulting final alloy, where the materials are separate or mixed, e.g. different
electrodes or mixed powders, resulting in a coating with the composition of the alloy.
[0032] Such coatings or protective layers serve to give protection from wear and corrosion
in the chemical industry, the pharmaceutical industry, the paper industry, the glass
industry, power industry, cement industry, waste and recycling, pulp and paper industry
and the plastics-processing industry. Coated parts are also used advantageously for
oil and gas exploration applications.
[0033] Generally the coating has a thickness in the range of 0.1 to 20 mm, preferably 1
to 10 mm.
Detailed description of preferred embodiments
[0034] The invention shall now be explained in more detail with reference to an embodiment
and a drawing which shows in detail in
- Fig. 1
- a diagram on the degree of volume loss in a standardized abrasion testing (ASTM G65)
in dependence upon the alloy composition,
- Fig. 2
- a diagram on the degree of weight loss in a standardized corrosion test in contact
with HCl in dependence upon the Ni content of the X5 alloy; and
- Fig. 3
- a diagram on the degree of weight loss in a standardized corrosion test in contact
with HNO3 in dependence upon the Ni content of the X5 alloy.
Example 1 (Sample X5)
[0035] A series of alloys is prepared by the fusion of metal elements and compounds into
a melt and producing two powders which are given in table 1 below:
Table 1
|
Fe |
C |
Si |
Cr |
Ni |
Mo |
B |
Powder A |
3.7 |
0.26 |
4.58 |
16.4 |
59.76 |
12.9 |
2.87 |
Powder B |
71.47 |
2.03 |
3.12 |
14.01 |
5.62 |
0 |
3.59 |
[0036] The Powder B (which is a Fe-based alloy) was blended with varying wt% of Powder A
(which is a Ni based wear resistant alloy which is also designated by No. "53606")
and then fused at 1.080 C. It was found that there was an optimal % of powder A for
wear and corrosion results that lay between 10 and 40 weight % and that best results
were obtained with 15% of Powder A
mixed with Powder B
[0037] This illustrated in
Fig 1. The 3 curves are wear rate data points obtained from the same fused mixtures but
tested with the ASTM G65 method at three independent test series (different times
and places). The volume loss is plotted on the y-axis in [mm
3] in dependence of the content of the Powder A in [wt%]. For all three test series
a characteristical low volume loss and therefore best wear resistance were obtained
with about 15% of Powder A mixed with Powder B.
[0038] In the following this 15% mixture of Powder A in Powder B alloy is called "X5". "X5"
is a Fe-based alloy containing no addition of other hard particles to increase its
hardness, such as Tungsten Carbide (WC). The following table 2 shows the composition
of the X5 alloy in comparison with an Fe-based alloy as it is disclosed in
DE 199 01 170 A1. It is obvious that the Ni-content of the X5-alloy is higher and its V-content is
lower (namely zero) and the carbon and chrome levels are also different.
Table 2
|
C |
Si |
Cr |
Ni |
Mo |
B |
V |
X5 |
1.7 |
3.5 |
16.0 |
16.0 |
2.0 |
3.5 |
0 |
DE 199 01 170 A1 |
2.0-4.0 |
0.5-3.5 |
6.0-15 |
2.0-7.0 |
1.5-7.5 |
2.0-4.5 |
6.0-14.0 |
[0039] For both alloys: the balance is Fe (in the case of X5 the Fe balance is 57 wt%).
The X5 alloy has a melting temperature of 1080° C. and low hardness of 58 HRC.
Wear test
[0040] In the ASTM G65 rubber wheel sand abrasion wear test the standard wear value of 13.68
mm
3 loss was recorded after 2000 revolutions of the wheel. This resulting wear resistant
value is at a similar to the well established nickel-based wear resistant material
called "12112", sold by Castolin Eutectic. This 12112 alloy is a blend of a NiCrBSi
12496 alloy matrix with 35% WC, which has the following composition:
Table 3
|
Fe |
C |
Cr |
B |
Ni |
Si |
Mo |
Alloy 12496 matrix |
3.88 |
0.78 |
14.8 |
3.13 |
73.31 |
4.1 |
0 |
[0041] This Ni based 12112 alloy (= blend of alloy 12496 alloy with 35% WC) has been sold
for at least 20 years and have been used to make Fused powder plates, sold under the
name of CP 112, by Castolin Eutectic.
[0042] The fact that the Alloy X5 achieved the same G65 wear resistance result as the established
12112 is a surprise and a breakthrough, as the 12112 needs to have 35% of expensive
WC added to achieve this value and an expensive Ni-based matrix. Alloy X5 is an Fe-based
product and has no WC present.
Corrosion tests
[0043] For corrosion tests specimens with near cylindrical shape were prepared by melting
of the test material in ceramic crucibles and cut into sliced with two exposed circular
surfaces. The measurement of weight and surface area was recorded.
[0044] The test material are the above mentioned Fe-based powder B (table 1) and Ni-powders
A (table 1, No. 53606) as well as powders of standard Ni-based alloys known as "12496"
and "12497"( a slight chemical modification of alloy 12496). Said Ni-based powders
were mixed with the Fe-based powder B (table 1) at various mixing ratios.
[0045] The slice specimens were exposed to HCl (33%), HN0
3 (55%), H
2SO
4 (96%) and acidic acid (80%) and the weight loss after 24h, 48h and 120h was measured.
The corrosion resistance as specific weight loss (weight loss in mg per cm
2 and 24h) was determined.
[0046] The diagram of
Fig. 2 illustrates the corrosion test results of three test series for different compositions
exposed to HCl (33%). The three curves are weight loss data points obtained from the
corrosion tests as explained above. The weight loss is plotted on the y-axis in [mg/(cm
2 x h)] in dependence of the fraction of the respective Ni-based A powder of the mixed
powders for the preparation of the specimens.
[0047] The diagram of
Fig. 3 illustrates the corrosion test results of three test series for different alloys
exposed to HN0
3(55%).The three curves are weight loss data points obtained from the corrosion tests
as explained above. The weight loss is plotted on the y-axis in [mg/(cm
2 x h)] in dependence of the content of the respective Ni-based A powder of the mixed
powders for the preparation of the specimens.
[0048] The results are as follows:
- Ni-based alloys (A, 12496, 12497) show good corrosion resistance against HCl. Fe-based
do not (Powder B). With increasing content of the Ni-based powder in the respective
powder blends, the corrosion resistance against HCl increases.
- Fe-based alloy (B) shows good corrosion resistance against HNO3. With increasing content of the Fe-based powder in the respective powder blends,
the corrosion resistance against HNO3 increases.
- Ni and Fe-based alloys are resistant against acetic acid and H2SO4.
- Adding Ni-based powders (A, 12496, 12497) to Powder B improves the corrosion resistance
against HCl but decreases the resistance against HNO3. The best balance is achieved with a Ni-based powder percentage of 5-15% as can be
seen in Figs. 2 and 3.
[0049] The optimum alloy blend of Ni-based powder into the Fe-based Powder B composition
is 15% (in wt% of the Ni-based powder) for HCl and HNO
3, with the use of Powder A as the best source of Ni-based alloy. This 15% / 85% mix
gives the composition of X5 according to this preferred embodiment of the invention.
This X5 composition also gives the lowest G65 wear resistance results.
1. A material comprising an alloy containing 13 to 16 percent by weight nickel (Ni),
13.5 to 16.5 percent by weight of chromium (Cr), 0.5 to 3 percent by weight of molybdenum
(Mo), 3.5 to 4.5 percent by weight of silicon (Si), 3.5 to 4 percent by weight of
boron (B) and 1.5 to 2.1 percent by weight of carbon (C), and optionally may contain
0.2-0.5 percent copper and less than 1 percent vanadium, balance iron (Fe).
2. A material according to claim 1, wherein the alloy contains no other elements except
impurities.
3. A material according to claim 1 or claim 2, wherein the alloy has a composition of
13 to 14 percent by weight of nickel (Ni), 14 to 16 percent by weight of chromium
(Cr), 1 to 3 percent by weight of molybdenum (Mo), 3.5 to 4.5 percent by weight of
silicon (Si), 3.5 to 4 percent by weight of boron (B), 1.8 to 2.1 percent by weight
of carbon (C) and 0.2 to 0.5 percent by weight of copper (Cu), balance iron (Fe).
4. A material according to any of the preceding claims, wherein the alloy has a hardness
of less than 60 HRC.
5. A material according to any of the preceding claims, wherein the alloy has a melting
point of less than 1150° C.
6. A material according to any of the preceding claims, wherein the alloy is a powder
or wire or the alloy is a coating on a metal substrate.
7. A material according to any of the preceding claims, wherein the alloy is free from
preformed hard particles, especially from tungsten carbide.
8. A material according to any of the preceding claims, wherein the alloy contains less
than 1 percent of weight of vanadium, most preferred the alloy is free from vanadium.
1. Werkstoff, umfassend eine Legierung, die 13 bis 16 Gewichtsprozent Nickel (Ni), 13,5
bis 16,5 Gewichtsprozent Chrom (Cr), 0,5 bis 3 Gewichtsprozent Molybdän (Mo), 3,5
bis 4,5 Gewichtsprozent Silizium (Si), 3,5 bis 4 Gewichtsprozent Bor (B) und 1,5 bis
2,1 Prozent Gewichtsprozent Kohlenstoff (C) enthält, sowie optional zwischen 0,2 bis
0,5 Prozent Kupfer und weniger als 1 Prozent Vanadium, der Rest ist Eisen (Fe).
2. Werkstoff nach Anspruch 1, dadurch gekennzeichnet, dass die Legierung außer Verunreinigungen keine anderen Elemente enthält.
3. Werkstoff nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet, dass die Legierung eine Zusammensetzung von 13 bis 14 Gewichtsprozent Nickel(Ni), 14 bis
16 Gewichtsprozent Chrom (Cr), 1 bis 3 Gewichtsprozent Molybdän (Mo), 3,5 bis 4,5
Gewichtsprozent Silizium (Si), 3,5 bis 4 Gewichtsprozent von Bor(B), 1,8 bis 2,1 Prozent
Gewichtsprozent Kohlenstoff (C) und 0,2 bis 0,5 Gewichtsprozent Kupfer (Cu) hat, der
Rest ist Eisen (Fe).
4. Werkstoff nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Legierung eine Härte von weniger als 60 HRC aufweist.
5. Werkstoff nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Legierung einen Schmelzpunkt von weniger als 1150 °C hat.
6. Werkstoff nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Legierung als Pulver oder Draht vorliegt, oder dass die Legierung eine Beschichtung
auf einem Metallsubstrat ist.
7. Werkstoff nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Legierung frei von vorgefertigten Hartpartikeln ist, insbesondere solchen aus
Wolframkarbid.
8. Werkstoff nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Legierung weniger als 1 Gewichtsprozent Vanadium enthält, vorzugsweise frei von
Vanadium ist.
1. Matériau comprenant un alliage contenant 13 à 16 pour cent en poids de nickel (Ni),
de 13,5 à 16,5 pour cent en poids de chrome (Cr), 0,5 à 3 pour cent en poids de molybdène
(Mo), 3,5 à 4,5 pour cent en poids de silicium (Si), 3,5 à 4 pour cent en poids de
bore (B) et 1,5 à 2,1 pour cent en poids de carbone (C), l'équilibre en fer (Fe).
2. Matériau selon la revendication 1, dans lequel l'alliage ne contient pas d'autres
éléments à l'exception des impuretés.
3. Matériau selon la revendication 1 ou la revendication 2, dans lequel l'alliage a une
composition de 13 à 14 pour cent en poids de nickel (Ni), 14 à 16 pour cent en poids
de chrome (Cr), de 1 à 3 pour cent en poids de molybdène (Mo), 3,5 à 4,5 pour cent
en poids de silicium (Si), 3,5 à 4 pour cent en poids de bore (B), 1,8 à 2,1 pour
cent en poids de carbone (C) et de 0,2 à 0,5 pour cent en poids de cuivre (Cu) équilibre,
le fer (Fe).
4. Matériau selon l'une quelconque des revendications précédentes, dans lequel l'alliage
a une dureté inférieure à 60 HRC.
5. Matériau selon l'une quelconque des revendications précédentes, dans lequel l'alliage
a un point de fusion inférieur à 1150°C.
6. Matériau selon l'une quelconque des revendications précédentes, dans lequel l'alliage
est une poudre ou d'un fil ou l'alliage est un revêtement sur un substrat métallique.
7. Matériau selon l'une quelconque des revendications précédentes, dans lequel l'alliage
est exempt de particules dures préformées, en particulier à partir de carbure de tungstène.
8. Matériau selon l'une quelconque des revendications précédentes, dans lequel l'alliage
contient moins de 1 pour cent du poids de vanadium, le plus préféré, l'alliage est
exempt de vanadium.