Improving the Durability of the Wheel Hub Bearings by Utilizing the Sub-zero Treatment Technique
 A novel sub-zero treatment technique is introduced to improve the durability of the wheel-hub bearings. The X-ray diffraction method was introduced to assess the sub-zero treatment effects on the retained austenite transformation. The impacts of the treatment conditions on the mechanical properties, such as hardness and impact toughness, were also evaluated. Furthermore, the accelerated life test was carried out to reveal the relationship between the process parameters of the sub-zero treatment and the durability of 52100 wheel hub bearing. The results showed that the sub-zero treatments could improve the durability of 52100 hub bearings, and the amount of the retained austenite transformation is proportional to the sub-zero treatment temperature. But too much of the retained austenite transformation could reduce the fatigue life. It is also convinced that there is an optimized treatment temperature could improve the durability of 52100 wheel hub bearings.