Raw material for shot-peening materials, finished wire, method of manufacturing shot-peening materials, and shot-peening materials

Abstract

The purposes of the present inventions are to provide a raw material for shot-peening materials wherein breaking a wire is prevented in obtaining a finished wire to improve the productivity, to provide a finished wire and a method of manufacturing shot-peening materials by which productivity is improved, and to provide shot-peening materials that are manufactured by that method. The finished wire, of which the area of carbides with a particle size of 2 μm or less is 80% or more of the total area, is manufactured by the steps of wiredrawing a raw material to obtain a wire, and repeatedly annealing and cold-drawing the wire. The raw material for the shot-peening materials comprises, by mass %, 0.95-1.10% carbon, 0.15-0.30% silicon, 0.40% or less manganese, 0.020% or less phosphorus, 0.010% or less sulfur, 1.40-1.60% chromium, 0.0015% or less oxygen, and the remaining materials of iron and unavoidable impurities. The method of manufacturing the shot-peening materials uses that raw material. The shot-peening materials are manufactured by that method.

Description

TECHNICAL FIELD[0001]The present inventions relate to a raw material for shot-peening materials, a finished wire, a method of manufacturing shot-peening materials, and shot-peening materials.BACKGROUND ART[0002]In an existing process of manufacturing shot-peening materials, a raw material, e.g., so-called bearing steel, is wiredrawn to obtain a wire. The wire is cut at the same length as its diameter. The cut wire is then thrown at a rigid wall to round off its edges. The rounded-off wire is ground to a predetermined degree of sphericity. Then, it is quenched and tempered to get a predetermined Vickers hardness. This process is well known (e.g., Japanese Laid-open Publication No. 2001-79766).DISCLOSURE OF INVENTION[0003]However, when a bearing steel that is not modified from a standard steel (e.g., a high carbon chromium bearing steel, SUJ2 of JIS (Japan Industrial Standards) G4805, of which the components are shown in Table 2) has been used as a raw material for shot-peening materi...

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Benefits of technology

[0004]The purpose of the present inventions is to solve that problem and to provide a raw material for shot-peening materials that is used for preparing a finished wire by wiredrawing. Breaking a wire is thus prevented in wiredrawing, so as to improve the productivity of the shot-peening materials. Another purpose is to provide a finished wire. Other purposes are to provide a method of manufacturing shot-peening materials by which improved productivity is achieved and to provide shot-peening materials that are manufactured by that method. That is, in the method a specific raw material for shot-peening materials is used for maintaining its purity to prevent a wire from breaking. A finished wire that is appropriate for subsequent processes is obtained from the raw material. The good structure of the raw material is maintanined after quenching and tempering by retaining fine carbides in the structure before quenching. The present inventions also provide shot-peening materials that have long lives and that induce appropriate compressive residual stress in a work. The present inventions further provide a method of manufacturing shot-peening materials that are readily quenched, to be suitable for shot-peening.

[0014]Since the raw material of the present inventions is selected so as to reduce the possibility of breaking a wire, the productivity is improved. In addition, even a small diameter wire can be processed at a high speed. The finished wire of the present inventions is suitable for manufacturing shot-peening materials. The method of manufacturing the shot-peening materials of the present inventions is high in both productivity and quality. The shot-peening materials of the present inventions are suitable for a shot-peening process.

Problems solved by technology

However, when a bearing steel that is not modified from a standard steel (e.g., a high carbon chromium bearing steel, SUJ2 of JIS (Japan Industrial Standards) G4805, of which the components are shown in Table 2) has been used as a raw material for shot-peening materials, there has been a problem of the wire breaking.

This does not improve the productivity of the shot-peening materials.

Thus, the productivity is significantly affected.

As a result, the productivity of shot-peening materials cannot increase.

Especially, for a wire having a diameter of less than 0.7 mm (for example, a diameter of 0.3 mm), a wire often breaks in a wiredrawing process and the problem becomes significant.

Thus, the most appropriate method of manufacturing shot-peening materials from a small diameter finished wire has not been established.

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