Microstructural study of cryogenically treated En 31 bearing steel

The effect of shallow cryogenic treatment (SCT) and deep cryogenic treatment (DCT) on the microstructure of En 31 bearing steel is studied in the present work. En 31 bearing steel subjected to cryogenic treatment showed more hardness than the conventionally heat treated steel. Fractography analysis of the cryogenic treated steel carried out using scanning electron microscope indicate the presence of equiaxed dimples and flat facets in SCT specimen, wide ranged size of dimples and microcracks in DCT specimen. Microstructural analysis is carried out using optical microscope to find out the probable mechanism for these effects and also to study the effect of tempering on cryogenically treated En 31 steel.