Effect of shot peening temperature on the microstructure induced by surface severe plastic deformation on an austenitic stainless steel

The mechanisms of microstructure modifications were investigated for a 316 L austenitic stainless steel subjected to Surface Mechanical Attrition Treatment (SMAT) across a wide temperature range (143 K to 773 K) and their effects on hardness and residual stresses evolutions determined. The research highlights how temperature modulates deformation mechanisms, transitioning from Transformation-Induced Plasticity (TRIP) and Twinning- Induced Plasticity (TWIP) at low temperatures to dislocation glide and dynamic recrystallization at elevated temperatures. These transitions lead to a distinct trade-off: while cryogenic SMAT enhances surface hardness and compressive residual stresses, warm SMAT, particularly at 773 K, facilitates the formation of a thick refined surface layer due to thermal softening effect and increases the deformation and residual stress gradient depth. This study provides new insights into tailoring surface properties through controlled temperature during SMAT, offering pathways to enhance mechanical performance for advanced applications.