Alloy for making a special steel for cold-working tools

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an alloy for making a special steel for cold-working tools.

[0002] More specifically, the alloy according to the present invention can be used for making tools such as knife blades, molds, dies, punches and the like.

[0003] As is known from the prior art, the making of a given alloy starting from a combination of different materials strictly depends on the rate composition thereof, since even a very small variation of the latter is such as to provide the obtained alloy with unexpected characteristics.

[0004] Thus, a variation even of an individual component of the alloy forming mixture, and in particular, a variation of the dose thereof, can affect the mechanical properties of the alloy, in an actually unexpected manner for one skilled in the art.

[0005] In particular, in the field of the steels for cold-working operations, is known that these steels can have high wear resistance and toughness features, in other words, the material must properly resist against pulsed forces, such as dynamic loads, impacts and the like.

[0006] Also known is the fact that the toughness is a feature contrasting with the wear resistance.

[0007] Other two very important mechanical properties are the machinability and pressure resistance of the sharp corners.

[0008] The above mentioned features provide the working tool with a comparatively high efficiency.

[0009] Several prior documents have already disclosed conventional steel materials, made by a combination of different components and used in cold-working operations, which, however, are not provided with satisfactory toughness and mechanical resistance or strength properties.

SUMMARY OF THE INVENTION

[0010] Accordingly, the aim of the present invention is to provide a steel alloy, which can be used for cold-working operations, and which is provided both with very high wear resistance and toughness properties.

[0011] The above mentioned aim, as well as yet other objects, which will become more apparent hereinafter, are achieved by an alloy for making a special steel for cold working tools, characterized in that said alloy comprises, alloyed with the iron, from 0.90 to 1.30 % by weight of carbon; from 7.0 to 8.5 % by weight of chromium; from 1.35 to 1.70 % by weight of molybdenum; from 2.0 to 2.60 % by weight of vanadium; and from 0.80 to 1.40 % by weight of tungsten.

[0012] To the above mentioned composition, obtained by the above disclosed combination of materials in the disclosed doses, are advantageously added manganese, in an amount corresponding to from 0.3 to 0.5 % by weight, and silicon, in an amount corresponding to from 0.9 to 1.30 % by weight.

[0013] Moreover, the alloy according to the present invention is characterized in that it further comprises phosphorus and sulphur in a rate of 0.020 % by weight of phosphorus and in a rate less than or equal to 0.010 % by weight for sulphur.

[0014] Experimental tests have shown that the mixture obtained by the combination of the above mentioned substances, in the amounts included in the indicated ranges, provides unexpected toughness, wear resistance, sharp corner compression resistance and machining properties, which are much greater than those of prior steels.

[0015] Thus, a main aspect of the present invention is that it allows to easily make cold-working tools having a higher efficiency and greater duration than those of like tools made starting from conventional steels.

[0016] The invention is susceptible to several variations and modifications, coming within the scope of the inventive idea.

Claims

1. An alloys for making a special steel for cold-working tools, characterized in that said alloy comprises, alloyed with the iron, from 0.90 to 1.30 % by weight of carbon; from 7.0 to 8.5 % by weight of chromium; from 1.35 to 1.70 % by weight of molybdenum; from 2.0 to 2.60 % by weight of vanadium; and from 0.80 to 1.40 % by weight of tungsten.

2. An alloy for making a special steel for cold-working tools, according to Claim 1,
characterized in that said alloy further comprises from 0.3 to 0.5 % by weight of manganese.

3. An alloy for making a special steel for cold-working tools, according to Claim 1 or 2, characterized in that said alloy further comprises from 0.9 to 1.30 % by weight of silicon.

4. An alloy for making a special steel for cold-working tools, according to one or more of the preceding claims, characterized in that said alloy further comprises phosphorus in a weight rate less than or equal to 0.020 and sulphur, in a weight rate less than or equal to 0.010.

5. An alloy for making a special steel for cold-working tools, according to one or more of the preceding claims, characterized in that said alloy comprises one or more of the disclosed and/or illustrated features.