Observation and Analysis of the Microstructure in Carburized Surface Layer of Steel 20Cr2Ni4A Treated with Conventional and Rare Earth Carburizing Processes

Observation and analysis with TEM show that the fine granular dispersed carbides in hypereutectoid zone of steel 20Cr2Ni4A are distributed in the matrix of large number of lath martensite after rare earth carburizing. But while treating by conventional carburization and double quench hardening the retained carbides are finer and more dispersive, and its matrix is perfectly twin martersite. The different microstructures of matrix around carbide are formed with different kinds of carburization processes.