The Study of Microstructure and Mechanical Properties of Two High Strength Steels

Abstract

The microstructure and mechanical properties of two high strength steels with different carbon content were studied by means of metallographic microscope, scanning electron microscope, transmission electron microscope and mechanical testing machine. The results showed that the microstructure of the 0.2C (wt.%) steel and 0.4C (wt.%) steel was tempered sorbite, a large number of granular carbides dispersed on the ferritic matrix. The carbides contained Fe₃C and M₆C (Fe₃Mo₃C) phase. Compared with 0.2C steel, the content of the carbides of 0.4C steel was larger, while the particle size was smaller. The tensile and yield strength of 0.4C steel were higher, but the elongation was lower and the toughness was worse. In addition, the hardness values of the two materials were basically the same.