Effect of HIP temperature on microstructural, mechanical, thermal and electrochemical properties of SUS316L-10Cu alloy fabricated by SLM

Abstract

In this study, a corrosion-resistant SUS316L–10Cu alloy was fabricated using a high-density Selective Laser Melting (SLM) process, followed by Hot Isostatic Pressing (HIP) post-treatment at various temperatures to systematically investigate microstructural evolution and corresponding mechanical, thermal, and electrochemical properties. Based on the theoretical full-melting energy density, 36 different SLM processing conditions were evaluated, and the optimal condition (240 W laser power and 1326 mm/s scanning speed) achieved the highest relative density. Subsequently, HIP treatment was conducted at 570, 770, 970, and 1170 °C under 1000 bar for 1 h. Micro-CT analysis revealed that internal porosity significantly decreased from 0.275 % in the as-built condition to 0.003 % after HIP at 1170 °C. Mechanical property evaluation showed that the specimen treated at 570 °C exhibited the highest hardness (225.6 HV) and tensile strength (676.7 MPa), whereas higher HIP temperatures resulted in decreased strength but improved ductility, reaching an elongation of 38.6 % at 1170 °C. Thermal conductivity increased from 12.67 W/m·K in the as-built condition and remained relatively stable above 770 °C due to Cu precipitation effects. Electrochemical corrosion tests further indicated improved stability in current density with increasing HIP temperature, suggesting enhanced corrosion resistance associated with Cu precipitation behavior. These results provide insights into the relationship between HIP temperature, Cu precipitation, and the resulting property evolution in SLM-fabricated SUS316L–10Cu alloys.