Bearing part and rolling bearing

Abstract

Each of an outer race, an inner race and a ball as a bearing part is a bearing part made of JIS standard SUJ2 and having a carbonitrided layer formed in a surface thereof, wherein, after heat treatment at a heating temperature of 500° C. for a retention time of one hour is performed, a Vickers hardness at a position with a depth of 0.02×T+0.175 (mm) from the surface is higher than a Vickers hardness at a core portion, which is a region where the carbonitrided layer is not formed in a thickness direction of the bearing part, by not less than 80 HV, where T represents the time of carbonitriding treatment for forming the carbonitrided layer.

1 . A bearing part made of JIS standard SUJ2 and having a carbonitrided layer formed in a surface thereof,
 wherein, after heat treatment at a heating temperature of 500° C. for a retention time of one hour is performed, a Vickers hardness at a position with a depth of 0.02×T+0.175 (mm) from said surface is higher than a Vickers hardness at a core portion, which is a region where said carbonitrided layer is not formed in a thickness direction of said bearing part, by not less than 80 HV, where T represents the time of carbonitriding treatment for forming said carbonitrided layer.   
     
     
         2 . The bearing part according to  claim 1 , wherein
 the time of said carbonitriding treatment is not less than 4 hours and not more than 10 hours.   
     
     
         3 . The bearing part according to  claim 1 , wherein
 the time of said carbonitriding treatment is not less than 6 hours and not more than 8 hours.   
     
     
         4 . A bearing part made of JIS standard SUJ2 and having a carbonitrided layer formed in a surface thereof,
 wherein, after heat treatment at a heating temperature of 500° C. for a retention time of one hour is performed after carbonitriding treatment for forming said carbonitrided layer and before grinding processing of said surface, a Vickers hardness at a position with a depth of 0.02×T+0.175+t (mm) from said surface is higher than a Vickers hardness at a core portion, which is a region where said carbonitrided layer is not formed in a thickness direction of said bearing part, by not less than 80 HV, where T represents the time of said carbonitriding treatment and t (mm) represents a thickness of said bearing part removed by said grinding processing.   
     
     
         5 . The bearing part according to  claim 4 , wherein
 the time of said carbonitriding treatment is not less than 4 hours and not more than 10 hours, and   said thickness is not more than 0.125 (mm).   
     
     
         6 . The bearing part according to  claim 4 , wherein
 the time of said carbonitriding treatment is not less than 6 hours and not more than 8 hours, and   said thickness is not more than 0.15 (mm).   
     
     
         7 . The bearing part according to  claim 1 , wherein
 said carbonitriding treatment is performed in a temperature range of not less than 840° C. and not more than 860° C.   
     
     
         8 . The bearing part according to  claim 1 , wherein
 a prior austenite crystal grain size is within a range of JIS standard No. 9 to No. 11.   
     
     
         9 . A rolling bearing comprising the bearing part as recited in  claim 1 . 
     
     
         10 . The rolling bearing according to  claim 9 , wherein
 the rolling bearing is any one of a deep groove ball bearing, a conical roller bearing, a cylindrical roller bearing, and a needle roller bearing.