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Keywords:

  • duplex stainless steel;
  • hot tensile test;
  • phase transformation

The aim of the present work was to evaluate initial secondary austenite phase microstructural changes (δ [RIGHTWARDS ARROW] γ′) in 2205 duplex stainless steel with N content of 0.36 wt% during hot tensile test. The results showed there is no secondary austenite microstructural change in zero deformation degree. The secondary austenite (γ2) phase transformation occurred only in the cooling process and under hot deformation condition. Initial secondary austenite (γ′) occurred within the ferrite matrix at the temperature range of 950–1150 °C. The precipitation of initial γ′ increased with the increase in aging time and deformation degree. With increasing time, a progressive transformation of initial γ′ to γ2 occurred. The orientation relationship between the initial γ′ phase and the δ matrix was different at varying high temperatures. A significant change in the hot deformation condition has been observed as a consequence of secondary austenite reformation. These results indicated the importance of control over the shape and volume fraction of secondary austenite phases on high nitrogen duplex stainless steels to improve hot ductility.