An Experimental Investigation into Residual Stress Control of 24CrNiMo Alloy Steel by Selective Laser Melting

Abstract

Residual stresses are a major problem in SLM forming of large-sized parts of high-performance materials. The purpose of this study is to investigate the effects of scanning strategy, preheating temperature, and heat treatment on residual stresses in SLM formed high-strength steels. An experimental method was used to investigate the residual stresses in SLM forming of high-strength steels. The peak and distribution of residual stresses can be changed by optimizing the scanning strategy. The most suitable scanning method is the strip rotation scanning strategy. The optimum substrate preheating temperature is 200 °C, and the residual stress of SLM forming can be significantly reduced by 62.5%. The annealing temperature has a clear effect on the residual stress release, and also has an impact on the microstructure and mechanical properties. After annealing treatment at 550 °C for 3 h, the residual stresses can be effectively released, while the uniformity of microstructure and mechanical properties is improved. Finally, the control strategy of residual stress, microstructure and mechanical properties of 24CrNiMo high-strength steel was obtained.