Hot deformation behavior and microstructural evolution of a superaustenitic stainless steel

Hot deformation behavior of the superaustenitic stainless steel type 1.4563 was investigated by conducting hot compression tests at the temperatures of 900-1050 °C and at strain rates in the range of 0.001-1 s−1. The microstructural changes were then characterized using optical and scanning electron microscopy as well as energy dispersive X-ray (EDX) microanalyses. The results showed that hot deformation at low temperatures, i.e. 900-950 °C, and at low and medium strain rates, i.e. 0.001-0.1 s−1, can lead to the formation of wormlike precipitates on grain boundaries resulting in the restriction or even inhibition of dynamic recrystallization. At higher strain rates or higher temperatures when respectively the time was too short or the driving force for dynamic precipitation was rather low, dynamic recrystallization occurred readily. Further, at low strain rates and high temperatures, where the occurrence of dynamic precipitation is difficult, there was no sign of particles. In this case, the interactions between solute atoms and mobile dislocations resulted in tiny serrations in the flow curves instead. The EDX analyses indicated that the chemical composition of the observed precipitates was (Cr, Fe, Mo)23C6.