Optimization of microwave processing parameters on powder-metallurgical 316L stainless steels
K. Veera Venkata Nagaraju, S. Kumaran, T. Srinivasa Rao
Abstract
Ultra-rapid microwave sintering of powder metals is recognized for better process advantages, namely less process time, uniform volumetric heating, and fine microstructural features that will improve mechanical and corrosion properties. In the present study, austenitic (316 L) stainless steel powder compacts were sintered using a multimode microwave hybrid heating system at solidus (1200°C and 1250°C) and super-solidus (1300°C) temperature with different holding times 30, 45 and 60 min. Mechanical as well as electrochemical responses were correlated with the microstructural features and densification characteristics. The samples sintered at 1300°C for 60 min have shown improved densification and higher tensile strength of 474.3 MPa with 22.1% ductility. It is also noted that an increase in sintering temperature resulted in excellent corrosion resistance in the order of ten times. The input process parameters and the output property responses are mathematically modeled with the help of RSM. The developed equations and experimental studies are in good agreement with output responses (sintered density, yield strength, %elongation, microhardness, corrosion rate) with 0.92 to 0.95 desirability. The validation of optimized output responses is evaluated by conducting confirmation tests at two conditions (1300°C for 60 min & 1300°C for 52 min) and are in line with regression model analysis.