Microstructure and properties of high power-SLM 24CrNiMoY alloy steel at different laser energy density and tempering temperature

In order to improve the manufacturing efficiency, the high power SLM technology was used to fabricate the 24CrNiMoY alloy steel. Effects of laser energy volume density (EVD) and tempering temperature on the microstructure and properties of HP-SLM 24CrNiMo steel were studied. Results show that as the EVD increases, the grows direction of lath martensite microstructure changes to disordered. When EVD is 120 J mm−3, the UTS of HP-SLM 24CrNiMoY steel reaches 1125 ± 15 MPa. High UTS is benefit from the fine martensite lath and high density of dislocations. Additionally, tempering treatment can reduce the dislocation density in martensite and promote the precipitation of ϵ carbides. After tempering at 500°C, the EL of HP-SLM 24CrNiMoY steel increased to 7.5% and the product of strength and plasticity increased by 37.8%. This study provides a technical reference for HP-SLM technology to prepare the high-performance 24CrNiMoY alloy steel.