Laser powder bed fusion of H13 tool steel with tungsten-lanthanum oxide particles addition

It has been demonstrated that the presence of residual austenite presents a significant challenge for H13 steel processed by laser powder bed fusion (LPBF) to achieve high tensile strength and ductility. In this work, tungsten-lanthanum oxide (W-La2O3) particle was introduced into H13 matrix to inhibit the formation of residual austenite during LPBF process. The effect of the addition content of W-La2O3 particles on the microstructure, densification and mechanical properties of W-La2O3 reinforced H13 steel composites was systematically investigated. The results show that the addition of W-La2O3 can effectively eliminate the carbon in H13 steel during the LPBF process by the formation of WCX diffusion layer and eliminate the fraction of the unstable austenite produced in H13 steel from 23.3% to 6.7%. Furthermore, the WCX diffusion layer effectively enhances the interface bonding between W-La2O3 and H13 steel matrix. These successfully realising improved mechanical properties with an ultimate tensile strength of 1216.8 MPa and a maximum strain of 7.4%.