Microstructure and mechanical behavior of additive manufactured Cr–Ni–V low alloy steel in different heat treatment

Abstract

Laser additive manufactured (LAM) components usually have non-equilibrium microstructures which leads to their high discreteness. The specimens were deposited in argon atmosphere and subsequent heat treatment are recommended for LAM components to achieve homogenous microstructures. In this paper, four different heat treatment procedures were designed, the microstructures evolution and mechanical properties of 12CrNi2V low alloy steel prepared by laser melting deposition (LMD) after different heat treatment were thoroughly studied. According to the EBSD analysis, the types and quantities of high-angle grain boundaries (HAGBs) in the tempered specimens were significantly higher than deposited specimen. The residual austenite (RA) content in the tempered specimen was about 280% higher than deposited specimen. The composition segregation and orientation gradient in the tempered specimens were significantly reduced, and the Schmidt factor value increased. The results of the experiment showed that when the tempering temperature was 620 °C, the specimens had the highest micro-hardness (383 HV) and tensile properties (966 MPa, 14.37%), and its elongation was about 150% higher than deposited specimen. This study provided an experimental and theoretical basis for the development of the subsequent heat treatment process for low alloy steel laser additive manufacturing.