JPH02236239A - Manufacture of high temperature wear-resistant co base alloy having excellent hot workability - Google Patents

Abstract

PURPOSE:To manufacture the high temp. wear-resistant Co base alloy having excellent hot workability by compositely adding specified amounts of Ca and Mg to the molten metal of an alloy having specified compsn. constituted of C, Cr, W, Mo, Si, Mn and Co and treating the mixture. CONSTITUTION:By weight, 0.001 to 0.3% Ca and 0.001 to 0.2% Mg (where Ca+Mg is regulated to <=0.35%) are compositely added to the molten metal of a Co base alloy contg. 0.05 to 2% C, 15 to 35% Cr, one or both of 2 to 20% W and Mo, one or both of 0.01 to 2% Si and 0.01 to 2% Mn, furthermore contg., at need, one or both of 1 to 25% Ni and Fe and the balance Co with inevitable impurities, which is subjected to refining treatment. In this way, the high temp. wear-resistant Co base alloy free from the deterioration of high temp. hardness, having high torsional frequency to fracture in a hot torsion test and having excellent hot workability can be obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention has excellent hot workability, and therefore can be formed into plates, bars, and various other parts by hot working in a short process and extremely easily. The present invention relates to a method for producing a high-temperature wear-resistant Co-based alloy that can be carried out with high yield.

[Conventional technology]

Conventionally, in general, ffiffl% (hereinafter % indicates sub-amount %), C: 0.05-2%, Cr: 15-35%, W
and one or two of Mo. 2-20%, SI: 0. Ol~2% and M mouth: 0. Contains one or two of Ni and Fe at 1 to 2%, and further contains one or two of Ni and Fe = 1 to 25%, with the remainder being Co and unavoidable. Since Co-based alloys having a composition consisting of impurities have excellent high-temperature wear resistance, they are widely used in various fields where these properties are required.

[Problem to be solved by the invention]

On the other hand, after melting and casting, the above-mentioned conventional Co-based alloys are processed into plate or bar material through the necessary steps of blooming forging (blowing rolling), hot forging (hot rolling), cold rolling, and heat treatment. , is manufactured into various parts, but because of its poor hot workability, hot working processes such as blooming forging, blooming, hot forging, and hot rolling require high temperatures. Processing has to be carried out in a very narrow temperature range, and therefore processing is required at a low processing rate, which results in repeated processing and heating, resulting in extremely poor productivity and the possibility of cracking. , there is also a problem in terms of yield.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors focused on the above-mentioned conventional Co-based alloy and conducted research to improve its hot workability. When the Co-based alloy is melted with the combined addition of , the resulting Co-based alloy has excellent hot workability, and even if the processing rate in the hot working process is high, there will be no cracking. They obtained the knowledge that hot processing with high yield is possible.

This invention was made based on the above findings, and includes: C: 0.05-2%, Cr: 15-35%, W
and one or two of Mo: 2 to 20%, one or two of Si: 0.01 to 2% and Mn + 0.01 to 2%, and further optionally, A Co-based molten metal containing 1 to 25% of one or two of Ni and Fc, with the remainder being Go and unavoidable impurities, is added in an amount of 0.001 to 0.
3% Ca and 0.001-0.2% Mg (but Ca
This method is characterized by a method for producing a high-temperature wear-resistant Co-based alloy with excellent hot workability by processing with a combined addition of (total amount of Mg: 0.35% or less).

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

A. Component composition (a) C The C component combines with Cr, W, and Mo components to form carbides and has the effect of improving wear resistance, but if its content is less than 0.05%, the desired result cannot be achieved. Wear resistance cannot be ensured, and if the content exceeds 2%, workability will decrease, so the content should be reduced to 0.
It was set at 0.05 to 2%.

(b) CrC' component not only dissolves solidly in the base material to improve its heat resistance, but also forms carbides as mentioned above to improve wear resistance, and the overall effect of the parentheses is to improve high-temperature wear resistance. However, if the content is less than 15%, the desired effect of improving the above effect cannot be obtained;
%, the content becomes brittle and the workability decreases, so the content was set at 15 to 35%.

(c) W and Mo These components have the effect of forming a solid solution in the base material and strengthening it, as well as forming carbides as described above to improve wear resistance. If the content is less than 20%, the desired effect cannot be obtained. On the other hand, if the content is less than 20%, it will become brittle and plastic working will become difficult. It was set at 20%.

(d) Sl and Mn Since these components have a deoxidizing effect, they are used as deoxidizing agents, but if their content is less than 0.01%, deoxidizing of the molten metal is insufficient; Even if the content exceeds Si:0.0, the deoxidizing effect will be saturated and further deoxidizing effect will not be exhibited. Ol~2% and Mn: 0.01~2%.

(e) Nl and Fe These components have the effect of solid-dissolving in the base material and improving ductility, thereby improving formability, so they are included as necessary, but the content is 1%. If the content is less than 2, the desired effect cannot be obtained;
If it exceeds 5%, the wear resistance will drop significantly, so
Its content was determined to be 1 to 25%.

B. Addition amount of Ca and Mg C
O-based alloys have excellent hot workability, and therefore adding only Ca or Mg alone cannot ensure the desired excellent hot workability. Combined addition of (a and Mg) is essential;
%, the desired hot workability cannot be obtained. On the other hand, if the addition amount is Ca: 0.3% and Mg: 0.2%, and the total amount of Ca and Mg is 0. ,35
If the amount exceeds Ca:a. (10
1 to OJ%, 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 explained using examples.

Using an ordinary vacuum melting furnace, prepare a Co-based molten metal having the composition shown in Table 1, and then melt the molten metal at a predetermined temperature within the range of 1350 to 1550°C, also as shown in Table 1. Both Ca and Mg in the added amounts shown in
Alternatively, by casting into an ingot having dimensions of diameter: l20 mm x length: 200 m+* and weight: approximately 20 kg, with or without addition of either one of the methods 1 to 30 of the present invention, comparative methods 1 to 8, and Conventional Methods 1 to 8 were carried out, respectively.

Next, the various ingots obtained as a result are subjected to blooming forging at a predetermined starting temperature within the range of 1,100 to 1,200°C and an end temperature of a predetermined temperature within the range of 900 to 1,100°C. Applied width: 120mm x thickness: 40
When the slab is made into a mm slab, the diameter of the central parallel part is 8! IIX Length: A test piece of 30m+s was cut out, and using this test piece, a hot twisting test was conducted at a temperature of 1L50'c, the number of twists until breakage was measured, and the hot workability was evaluated. did. In addition, for the purpose of evaluating hot wear resistance, the Vickers hardness at 800°C after solution treatment at 100°C for 30 minutes was determined as fiP1.

The results of these measurements are shown in Table 1.

〔Effect of the invention〕

From the results shown in Table 1, the Co-based alloys produced by methods 1 to 30 of the present invention are superior to the Co-based alloys produced by conventional methods 1 to 8, which do not involve the addition of Ca and Mg. It is clear that compared to the base alloy, it exhibits even better hot workability without a decrease in high-temperature hardness, and as seen in the Co-based alloys produced by Comparative Methods 1 to 8, Ca and Even if either one of Mg is added,
Furthermore, even if both are added, it is clear that the desired hot workability cannot be ensured if the amount added is too small or too large outside the scope of the present invention.

As described above, according to the method of the present invention, it is possible to produce a high-temperature wear-resistant Co-based alloy with excellent hot workability. When manufacturing plates, bars, and various other parts through hot processing such as hot rolling or hot rolling, no cracks occur even at high processing rates, ensuring high productivity and yield. This brings about industrially useful effects such as the ability to

Claims (1)

[Claims] (1) In weight%, C: 0.05-2%, Cr: 15-35%, W and M
Contains one or two of o: 2 to 20%, one or two of Si: 0.01 to 2% and Mn: 0.01 to 2%, and the remainder is Co and unavoidable A molten Co-based alloy having a composition consisting of impurities is added in an amount of 0.001 to 0.3% Ca and 0.001 to 0.2% Mg (total amount of Ca and Mg: 0.35%). 1. A method for producing a high-temperature wear-resistant Co-based alloy with excellent hot workability, characterized by processing by the combined addition of (below). (2) In weight%, C: 0.05-2%, Cr: 15-35%, W and M
o: 2 to 20%, one or two of Si: 0.01 to 2% and Mn: 0.01 to 2%, and further contains Ni and Fe. One or two of the following: A molten Co-based alloy having a composition of 1 to 25%, with the remainder consisting of Co and unavoidable impurities, with an added amount of 0.001 to 0.3% Ca. High-temperature wear-resistant Co-based material with excellent hot workability characterized by processing by combined addition of 0.001 to 0.2% Mg (however, total amount of Ca and Mg: 0.35% or less) Alloy manufacturing method.