Executive Summary : | The main goal of this project is to develop an additive manufacturing process for high-speed tool steel (HSS), M2 type material with improved crack resistance and increased mechanical and wear properties. M2 HSS alloy is widely used in cutting tools, moulds, and rollers due to its high hardness and wear resistance. However, M2 HSS alloy has problems due to the severe hot cracks and solid-state cracks during laser powder bed fusion (L-PBF) processing, and it does not meet the mechanical requirements for any industrial applications. This constitutes a need for AM processible M2 tool steel and detailed investigation to improve the processing window for the L-PBF process. Selective Laser Melting (SLM), which utilizes a laser as a thermal energy source to melt the powder, has been chosen as the preferred AM technology. The development of the L-PBF additive manufacturing process for M2 tool steel will focus on two approaches: (1) Varying process strategy of L-PBF such as remelting between layers, varying scanning strategy (chess pattern), and heating of base plate up to 500 ℃ to avoid cracking issue. And (2) Study the laser powder bed fusion (LPBF) processability of HSS M2 tool powder modified by adding sub-micron inoculants like W, WC, and Zr powder particles and correlate the microstructure formation during solidification and mechanical performance of manufactured parts. The L-PBF process development will be performed to ensure a defect-free AM part. A deep characterization of AM-built altered M2 tool steel will be carried out, including microhardness, compressive, impact, fatigue, and tribological properties under room and high-temperature conditions. The effect of various post-built heat-treatment conditions on microstructural evolution will be analyzed, and process-structure-property correlations will be established. Finally, the processibility of M2 tool steel by L-PBF will be validated at the component level. |