Effect of processing route on microstructure and impact toughness of duplex stainless steel

The main objective of the present work is to study the effect of change in processing route and resulting changes in microstructure and mechanical properties, mainly impact toughness, of F51 duplex stainless steel material. Upsetting of F51 cylindrical bars were done in the temperature range of 1220-1210°C. After the upsetting operation some bars were water quenched and some were air cooled. The samples were further solution treated at 1050°C for 30 min. Optical microscopy, scanning electron microscopy, EBSD, quantitative metallography and impact testing were used to study the microstructure and mechanical properties during the different stages of processing route. It has been observed that microstructures of both routes have a significant difference and air cooled samples after the forging showed good impact toughness than the water quenched sample. Detailed analysis was done and the results suggest that, a small change in the processing route makes enormous difference in the final achieved properties.