Microstructural Analysis of Carbides in Steel by Electrochemical Extraction Technique

A tempering process is used to increase the ductility and toughness of steel after quenching. During tempering, the carbides nucleate and grow. The size and distribution of carbides can have a great effect on the mechanical property of steel. In this paper, X-ray diffraction (XRD) was used to determine the carbides size and crystal structure. Optical microscopy and scanning electron microscopy (SEM) were used to characterize the shape and distribution of carbides. Carbides for AISI 4140 Steel and 420 stainless steel with different tempering temperature were investigated. Fe₃C was found in AISI 4140 steel and Cr₂₃C₇ was found in 420 stainless steel.