| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a needle roller bearing which is capable of sufficiently ensuring the durable service life of a needle roller even under a service condition where foreign matters intrude into the bearing and the temperature rise is high. SOLUTION: A steel in which the content of Si and Mn is increased, is used for a material of a needle roller 1, and the needle rollers are carbonitrided, and hardened so that the retained austenite in a carbonitrided layer 1a formed on a surface layer part of the needle rollers 3 is 20-40 vol.%, and the surface hardness is >=Hv 750. Generation of the surface separation attributable to generation and propagation of cracks is suppressed, and the durable service life of a needle roller bearing is remarkably improved even under a service condition where foreign matters intrude into the bearing and the heat generation is large at a bearing part.</p> |
