Eliminating mixed grain structure of Fe–22Cr–25Ni austenitic heat–resistant steel via strain–induced M23C6 precipitation and re–dissolution

Abstract

Austenitic stainless steels are prone to mixed grain structure (MGS) defect during solution treatment or hot work. We demonstrate that strain–induced continuous M23C6 precipitates at grain boundaries (GBs) enable obtaining uniform deformed structures through hot–rolling at 1000 °C and 1100 °C. After solution treatment of the hot–rolled specimens at 1200 °C for 10–60 min, static recrystallization occurs. After the solution time exceeds 10 min, the M23C6 precipitates at GBs dissolve completely. The recrystallized grains grow normally as the solution time increase, and there is no abnormal grain growth. Strain–reduced the M23C6 precipitation can pin GBs during the dissolution process, thereby eliminating MGS defect.

Keywords

• Austenitic heat–resistant steel
• Mixed grain structure
• Hot–rolling
• Strain–induced M23C6 precipitation