THE EFFECTS OF ALLOY ELEMENTS AND HEAT TREATMENTS ON WHITE STRUCTURE FLAKING IN ROLLING BEARINGS
In recent years, the unique flaking termed white structure flaking or white etching cracks can be seen in wind turbine bearings. Microstructural change called white structure has been observed in the flaking cross sections. The mechanism of white structure flaking has not been fully studied. However, it has been reported that this flaking is induced by hydrogen generated by decomposition of lubricants. In this study, the effects of alloy elements and heat treatments on white structure flaking in rolling contact fatigue were investigated. The specimens and bearings were made of several variations of steel with different alloy elements and heat treatments. The rolling contact fatigue test were carried out by using the specimens which were charged with hydrogen. The bearing life tests were carried out by using a special lubricating oil. By increasing the alloy contents, formation of white structure was delayed and white structure flaking life was increased.