氮等离子体浸没离子注入技术改善轴承钢滚动接触疲劳寿命和机械性能的研究

研究了氮等离子体浸没离子注入(N-PIII)技术处理后GCr15轴承钢表面的滚动接触疲劳特征和机械性能。测试了改性前后试样的滚动接触疲劳寿命和磨痕光学形貌、摩擦磨损行为及纳米压痕硬度。结果表明,处理后试样的最大显微硬度较基体增大近一倍,摩擦系数从0.95下降到0.15。在赫兹接触应力为5.1 GPa,90%置信区间下的L10和L50寿命分别增加了99.6%和236.3%。分析不同处理参数下的Weibull分布曲线和光学显微形貌可知,脉冲偏压、材料内部缺陷、基体表面粗糙度、注入时间和N离子注入剂量对疲劳寿命均有很大影响。疲劳寿命和相关机械性能的改善主要源于N-PIII处理所导致的氮化物强化相和残余压应力的共同作用。

Improving on the Rolling Contact Fatigue Life and Mechanical Behaviors of Bearing Steel by Nitrogen Plasma Immersion Ion Implantation

Rolling contact fatigue(RCF) life and surface mechanical perforcmances of GCr15 bearing steel has been studied by nitrogen plasma immersion ion implantation(NPIII).Testing investigations include Optical microscopy(OM),friction and wear behavior and nanoindentation measurement.Results show that the RCF life and mechanical properties of treated samples improved significantly.The maximum microhardness of treated samples is nearly as twice as that of substrate's,and the friction coefficient decreases from 0.90 to near 0.15.The L_(10) and L_(50) life of the treated specimens increase by 99.6% and 236.3% at a Hertzian stress of 5.1 GPa and 90% confidence level,respectively.The optical microscopy morphology and Weibull distribution curves test indicate that the pulse bias voltage,interior defects of substrate,surface roughness,implantation time and N~ implantation dose are all play an important role on the RCF life of treated sample.The main reason is that the nitrogen compounds phase and residual compressive stress exist in the surface and near-surface of treated specimen.