Effects of cooling method and elements segregation on the martensite-pearlite banded structure of high carbon bearing steel

Abstract

In this study, the effects of the cooling method and alloying element segregation on the abnormal zonal structure of high-carbon bearing steel were investigated by reheating, controlled rolling, and controlled cooling of the sample. The microstructure and alloy segregation characteristics of the abnormal strip structure in the hot-rolled plate of the steel were revealed by optical microscopy, scanning electron microscopy, transmission electron microscopy, and electron probe x-ray microanalysis. The JMatPro thermodynamic software was used to examine the relationship between the alloy elements and banded structure defects of the hot-rolled sheet and analyse the causes of the defects and their elimination methods. The results show distinct positive segregation of Cr/Mn and negative segregation of C in martensite-pearlite banded structure defects in hot-rolled plates. The martensite-pearlite banded structure is formed by the interaction between the cooling rate and the segregation of alloying elements after hot rolling. Studies have found that segmented cooling (slow cooling-air cooling) can eliminate the martensite-pearlite banded structure.