Comparison of microstructure and properties of Cr8 die steel before and after tempering

This paper observed and analyzed the microstructure, hardness, and tensile mechanical properties of Cr8 steel using the tensile testing machine, rockwell hardness tester, and metallographic microscope. The results showed that before quenching the carbides in Cr8 steel have different morphologies and obvious aggregation along the streamline and have low tensile strength and hardness. After quenching, some carbides dissolve into the matrix and undissolved carbides which are M 7 C 3 and M 23 C 6 are distributed on martensite in the shape of large particles. The tensile strength of the material reaches 1536 MPa and the hardness reaches 59 HRC.