The effect of retained austenite (γ_R) on the rolling contact fatigue (RCF) properties of carburized SAE4320 steel was carefully investigated. We prepared specimens comprising four volume fractions of γ_R from 6% to 39% by controlling the subzero heat treatment. The effect of γ_R on the RCF was investigated using hardness measurements, X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy. The RCF test revealed that the sub-surface initiated spalling life was prolonged as the volume fraction of γ_R increased. In the area at the depth z₀ where the orthogonal shear stress was maximum, the majority of the γ_R was transformed to martensite, thus resulting in a significant increase in the Vickers hardness. The result of SEM observation showed that the region initially comprising γ_R exhibited a high resistance to RCF. Moreover, the TEM analysis revealed that the initial γ_R region changed into a mixture of very fine hard martensite and some unchanged γ_R during RCF. This suggests that the transformation of γ_R into fine hard martensite during RCF contributed to the improvement of the RCF life.

残留奥氏体（的效果γ _{- [R}渗碳SAE4320钢）上的滚动接触疲劳（RCF）性质进行了仔细研究。我们制备了包含四个体积分数的样品γ _{- [R}通过控制零下热处理从6％至39％。的效果γ _ř使用硬度测量，X射线衍射在RCF进行了研究，扫描电子显微镜（SEM）和透射电子显微术。该RCF测试，发现该子表面引发剥落寿命延长为一体的体积分数γ _{- [R}增加。在深度z ₀处，正交剪应力最大的区域中，大部分γ _{- [R} ，转化马氏体，从而导致在维氏硬度一个显著增加。的SEM观察结果表明，最初包含所述区域γ _{- [R}表现出对RCF高电阻。此外，TEM分析表明，初始γ _{- [R}区域变成和非常细的硬质的马氏体的混合物的一些不变γ _{- [R} RCF期间。这表明，改造γ _[R RCF期间成细硬马氏体促成了RCF生活的改善。