Optimization of Heat Treatment Parameters for Austenitic Stainless Steel Cladding Using the Taguchi Method

Hot-rolled A283 Gr C carbon steel/A240 TP 316L stainless steel-clad plates are widely used in structural applications. However, the hot-rolling process introduces residual stresses and microstructural heterogeneities near the interface, which can adversely affect mechanical performance. This study aims to optimize stress-relief annealing parameters for hot-rolled A283 Gr C/A240 TP 316L-clad steel in order to enhance toughness while preserving microstructural integrity. A Taguchi experimental design based on an L9 orthogonal array was employed to evaluate the effects of holding temperature, holding time, and heating/cooling velocity on Charpy impact toughness. Signal-to-noise (S/N) ratio analysis and ANOVA were used to identify the most influential parameters. Microstructural observations, microhardness profiling, and Charpy impact testing were conducted before and after heat treatment. The results indicate that stress-relief annealing does not alter the base microstructures of either the carbon steel substrate or the austenitic stainless steel-clad layer, nor does it induce carbide precipitation or secondary phase formation in the A240 TP 316L stainless steel. A noticeable reduction in the thickness of the decarburized ferrite zone near the interface was observed, suggesting improved interfacial stability. Microhardness measurements revealed a moderate decrease in hardness near the interface, accompanied by a significant increase in Charpy impact toughness under optimized conditions. ANOVA results show that holding temperature is the dominant factor influencing toughness, followed by heating/cooling velocity, while holding time has a minor effect. The optimal stress-relief annealing conditions were identified as 550 °C for 45 min, with a heating/cooling velocity of 100 °C/h. These findings demonstrate that the Taguchi method is an effective approach for optimizing heat treatment parameters and improving the mechanical integrity of hot-rolled stainless steel-clad plates.