Study of Optimal Magnification for Retained Austenite Evaluation in Low carbon Case Hardening steel Using Metallurgical Microscopy

This study on optimum magnification at which Retained austenite to be evaluated by comparing the difference in determining the retained austenite in low carbon carburizing alloy steel using the optical metallurgical micrographic method and X-ray diffraction method. The retained austenite phase will be in surface and color is white in nature also its presented in between the martensite needles. It can be distinguished as separate micro-constituents by using image analyzing software. In another method the RA measurements were carried out on the surface by PROTO iXRD Retained austenite measuring system using Cr K radiation. The (211) and (200) reflections of Martensite and (220) and (200) reflections of Austenite were made for this estimation. However, the calculated values of retained austenite by metallurgical microscope in different magnifications are not identical. In this paper, Chemical composition, sample preparation for metallographic and XRD analysis, correlation of metallographic and X ray radiography results were discussed. However, 500x magnification metallographic results correlate best to the result of Quantitative iXRD analysis