The hot deformation process of GCr15 bearing steel was simulated by the MMS300 thermal mechanical simulator. The effect of final deformation temperature on microstructure was investigated. The results show that, within the range of 770-870℃,the microstructure of GCr15 bearing steel consists of lamellar pearlite plus proeutectoid carbide which is distributed along the grain boundary and surrounded by ferrite thin film. With the increase of the final deformation temperature,the grain size and pearlite colony size both increase,the mean interlamellar spacing of pearlite decreases slightly and the hardness increases. By means of regression analysis,the fitted curve of Vickers hardness vs the reciprocal of mean interlamellar spacing is given by HV=38.3S-1+92.7. The degree of carbide network increases when the final deformation temperature increases within the range of 810-870℃. Compared with 810℃,the degree of carbide network is more serious at the final deformation temperature of 770℃ and 790℃.
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