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.

1 . A raw material for shot-peening materials comprising, by percentages by mass:
 0.95-1.10% carbon, 0.15-0.30% silicon, 0.40% or less manganese, 0.020% or less phosphorus, 0.10% or less sulfur, 1.40-1.60% chromium, 0.0015% or less oxygen, and remaining materials of iron and unavoidable impurities.   
     
     
         2 . A finished wire for shot-peening materials prepared by the steps of:
 wiredrawing the raw material for the shot-peening materials of  claim 1  to obtain a wire; and   repeatedly annealing and cold-drawing the wire to obtain a finished wire, wherein an area of carbides with a particle size of 2 μm or less is 80% or more of a total area of the finished wire.   
     
     
         3 . The finished wire for shot-peening materials of  claim 2 , wherein the annealing is performed at a temperature of 720° C. or lower. 
     
     
         4 . A method of manufacturing shot-peening materials comprising the steps of:
 cutting and plastic-forming the finished wire for the shot-peening materials of  claim 2  to obtain raw shot-peening materials; and quenching and tempering the raw shot-peening materials.   
     
     
         5 . The method of manufacturing the shot-peening materials of  claim 4 , wherein tempering parameters=T ((21.3−5.8×[C])+log(t), where T denotes tempering temperature (K), t tempering time (hr), and [C] carbon content (%), are 6200-7300. 
     
     
         6 . The method of manufacturing shot-peening materials further comprising the step of:
 plastic-forming the shot-peening materials that are manufactured by the method of  claim 4  or  5 .   
     
     
         7 . A method of manufacturing shot-peening materials comprising the steps of:
 wiredrawing the raw material for the shot-peening materials of  claim 1  to obtain a wire;   repeatedly annealing and cold-drawing the wire to obtain a finished wire;   cutting and plastic-forming the finished wire to obtain raw shot-peening materials; and   quenching and tempering the raw shot-peening materials.   
     
     
         8 . The method of manufacturing the shot-peening materials of  claim 4 ,  5 , or  7 , wherein a temperature of the quenching is 820-850° C. 
     
     
         9 . The shot-peening materials manufactured by the method of  claim 4  or  7 , wherein a matrix of a structure thereof is tempered martensite, and fine carbides precipitate therein, and wherein a ratio of an area of carbides to a total area is 70-95%. 
     
     
         10 . Shot-peening materials manufactured by the steps of:
 wiredrawing a raw material for shot-peening materials comprising, by percentages 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 remaining materials of iron and unavoidable impurities to obtain a wire;   annealing and cold-drawing the wire to obtain a finished wire;   cutting and plastic-forming the finished wire to obtain raw shot-peening materials; and   quenching and tempering the raw shot-peening materials,   wherein a matrix of a structure thereof is tempered martensite, and fine carbides precipitate therein, and wherein a ratio of an area of carbides to a total area is 70-95%.   
     
     
         11 . The shot-peening materials of  claim 10 , wherein a Vickers hardness thereof is 950 HV-1050 HV.