Retained austenite may be helpful or detrimental to the life of heat-treated components, but it can be difficult to accurately measure in manufactured steels. Commonly used visual sample investigations are subjective and often incorrect, magnetic measurements require part-specific calibration, and electron backscattering involves expensive equipment, intensive sample preparation, and long measurement times. Recent developments in X-ray diffractometry, however, provide measurements in minutes and can compensate for the influence of carbides in high-carbon steels as well as texture orientations in rolled sheet metals. This paper discusses the use of X-ray diffraction for measuring retained austenite and compares and contrasts it with other methods. It also provides a brief review of the formation of austenite and its effect on carburized gears, TRIP steels, and bearings.

Microstructure refinement strategies for carburized steel were evaluated to assess their effect on the fatigue performance of case carburized components. Commercial 52100 steel samples were subjected to various treatments and analyzed to determine the micro-geometry of plate martensite and the size distribution of retained-austenite regions. Decreasing reheat temperature produced finer austenite grain size, while multiple reheating cycles helped narrow grain size distribution. The refinement of austenite grain size also led to a reduction in martensite plate size and finer distribution of retained austenite.