JP2745647B2 - Method for producing high-temperature wear-resistant Co-based alloy with excellent hot workability - Google Patents

Description

[Detailed Description of the Invention] [Industrial application field] The present invention is excellent in hot workability, and therefore, can be formed into a plate, a bar, and various members by hot working in a short process and extremely. The present invention relates to a method for producing a high-temperature wear-resistant Co-based alloy that can be performed at a high yield.

[Conventional technology]

Conventionally, in general, by weight% (hereinafter,% means weight%), C: 0.05 to 2%, Cr: 15 to 35%, one or two of W and Mo: 2 to 20% And, if necessary, one or two of Ni and Fe: 1 to 25%, and a Co-based alloy having a composition consisting of Co and unavoidable impurities with the balance being excellent in high-temperature wear resistance. Because of its properties, it is widely used in various fields where these characteristics are required.

[Problems to be solved by the invention]

On the other hand, the above-mentioned conventional Co-based alloy undergoes the necessary steps of slab forging (bulking rolling), hot forging (hot rolling), cold rolling, and heat treatment after melting and casting. In addition, although it is manufactured into various members, it is inferior in hot workability. Processing must be performed in a very narrow temperature range, and therefore processing must be performed at a low processing rate.As a result, processing and heating are repeated, resulting in extremely poor productivity and easy cracking. There is also a problem in terms of yield.

[Means for solving the problem]

Therefore, the present inventors focused on the above-mentioned conventional Co-based alloy from the above-described viewpoints and conducted research to improve the hot workability thereof.As a result, Ca and Mg were produced during melting. When combined and added, the resulting Co-based alloy has excellent hot workability, and does not generate cracks and the like even when the working ratio in the hot working process is increased. We obtained the knowledge that hot working at a yield is possible.

The present invention has been made based on the above findings, and contains C: 0.05 to 2%, Cr: 15 to 35%, and one or two of W and Mo: 2 to 20%. And, if necessary, one or two of Ni and Fe: 1 to 25%, and a Co-based alloy melt having a composition of Co and unavoidable impurities, the balance being 0.001%. ~ 0.3% Ca and 0.001 ~ 0.2% Mg (However, Ca and Mg
(A total amount of 0.35% or less), and a method of producing a high-temperature abrasion-resistant Co-based alloy having excellent hot workability by treating with a composite addition of

Next, the reason why the component composition of the Co-based alloy melt and the amounts of Ca and Mg added in the method of the present invention are limited as described above will be described.

A. Component Composition (a) C The C component has the effect of forming carbides by combining with the Cr, W, and Mo components and improving the wear resistance. If the wear resistance cannot be ensured, and if the content exceeds 2%, the workability decreases, so the content is set to 0.05 to 2%.

(B) Cr The Cr component forms a solid solution with the base material to improve its heat resistance, and also forms a carbide as described above to improve its wear resistance. However, if the content is less than 15%, the desired effect cannot be obtained, while if the content exceeds 35%, embrittlement occurs and workability is reduced. Therefore, the content was determined to be 15 to 35%.

(C) W and Mo These components have a function of improving the wear resistance by forming a carbide as described above, in addition to forming a solid solution in the base material and strengthening the solid solution. If the content is less than 20%, the desired effect cannot be obtained, while if the content exceeds 20%, the material becomes brittle and plastic working becomes difficult. %.

(D) Ni and Fe These components improve the ductility by forming a solid solution in the base material,
Since it has the effect of improving the moldability, it is contained as necessary. However, if its content is less than 1%, the desired effect cannot be obtained in the above-mentioned effect, while if its content exceeds 25%, The content was determined to be 1 to 25% because the wear resistance was significantly reduced.

B. Addition amount of Ca and Mg
Co-base alloys have excellent hot workability, and therefore, even if Ca alone or Mg alone is added, the desired excellent hot workability cannot be ensured. It is indispensable to use
The desired hot workability cannot be obtained even if the addition amount of any of Mg and Mg is less than 0.001%, while the addition amounts of Ca: 0.3% and Mg: 0.2%, respectively, and Ca and Mg
If the total amount exceeds 0.35%, the hot workability is rather reduced.
0.001 to 0.3%, Mg: 0.001 to 0.2% (however, the total amount of Ca and Mg must be 0.35% or less).

〔Example〕

Next, the method of the present invention will be specifically described with reference to examples.

Using a normal vacuum melting furnace, a Co-based alloy melt having the component composition shown in Table 1 was prepared. Then, at a predetermined temperature within a range of 1350 to 1550 ° C., the first
Add the amount of Ca and Mg shown in the table, both or either, or without adding, diameter: 120mm ×
The methods 1 to 28 of the present invention, the comparative methods 1 to 7, and the conventional methods 1 to 7 were respectively carried out by casting into an ingot having a length of 200 mm and a weight of about 20 kg.

Next, for various ingots obtained as a result of this, starting temperature: a predetermined temperature in the range of 1100 to 1200 ° C., ending temperature: ingot forging under conditions of a predetermined temperature in the range of 900 to 1100 ° C. The width of the slab is 120mm x thickness: 40mm. However, a test piece having a diameter of 8 mm and a length of 30 mm was cut out, and a hot torsion test was performed at a temperature of 1100 ° C. using the test piece.
The number of twists up to breaking was measured to evaluate hot workability. In addition, for the purpose of evaluating hot wear resistance, 1100 ° C
The Vickers hardness at 600 ° C. after the solution treatment for 30 minutes was measured. Table 1 shows the results of these measurements.

〔The invention's effect〕

From the results shown in Table 1, the Co-based alloys produced by the methods 1 to 28 of the present invention showed that the combined addition of Ca and Mg
Compared to the Co-based alloys manufactured by the conventional methods 1 to 7 without the addition treatment, it is apparent that the hot workability is further improved without lowering the high-temperature hardness. As seen in the Co-based alloys manufactured in
Even if either one of Mg and Mg is added, or both are added, the desired amount of hot workability is secured even if the amount added is too small or too large outside the range of the present invention. Obviously you can't.

As described above, according to the method of the present invention, it is possible to produce a high-temperature wear-resistant Co-based alloy having excellent hot workability. And hot rolling such as hot rolling
Furthermore, when manufacturing various members, cracks and the like do not occur even when the processing rate is increased, so that industrially useful effects such as high productivity and yield can be ensured. .

Claims (2)

(57) [Claims] (1) C: 0.05 to 2%, Cr: 15 to 35%, one or two of W and Mo: 2 to 20% by weight, the balance being Co and unavoidable impurities It is intended to treat a Co-based alloy melt having a composition consisting of 0.001 to 0.3% of Ca and 0.001 to 0.2% of Mg (however, the total amount of Ca and Mg: 0.35% or less), in terms of the addition amount. A method for producing high-temperature wear-resistant Co-based alloys with excellent hot workability. 2. The composition contains, by weight%, C: 0.05 to 2%, Cr: 15 to 35%, one or two of W and Mo: 2 to 20%. One or two of them: 1 to 25%, and the balance is a Co-based alloy melt having a composition consisting of Co and unavoidable impurities, with the addition amounts of 0.001 to 0.3% Ca and 0.001 to 0.2% A method for producing a high-temperature wear-resistant Co-based alloy with excellent hot workability, characterized by treating by adding Mg (however, the total amount of Ca and Mg: 0.35% or less).