The mechanical properties such as strength, ductility, and toughness were examined in static- and dynamic-tensile tests, V-notched Charpy impact test, and dynamic fracture toughness (J-integral) test for three sorts of steels with the ausform of 25% rolling: (steel A) Fe-0.3C-9Cr-8Ni-4Mo-2Mn, (steel B) Fe-0.3C-9Cr-8Ni-4Mo-10Mn, and (steel C) Fe-0.3C-9Cr-12Ni-4Mo-10Mn.
For steel A, besides the usual TRIP in a narrow sense caused by the deformation induced α'-martensite, a different type of TRIP in a wide sense was observed in the static tensile test, which was due to the substructure such as stacking fault and mechanical twin. In dynamic tensile test and Charpy impact test for steel A, TRIP slightly occurred.
For steels B and C, TRIP in a wide sense alone occurred in the tests because of stabilization and low stacking fault energy of austenite matrix by high Mn content. High Mn TRIP steels provided an excellent dynamic fracture toughness.
