Structural Transformations and Mechanical Properties of Metastable Austenitic Steel under High Temperature Thermomechanical Treatment

The effect of high-temperature thermomechanical treatment on the structural transformations and mechanical properties metastable austenitic steel AISI 321 type is investigated. features grain defect microstructure were studied by scanning electron microscopy with back-scatter diffraction (SEM EBSD) transmission (TEM). It shown that in initial state after solution average size 18 ?m. A high (?50%) fraction twin boundaries (annealing twins) was found. In course hot (with heating up to 1100 °C) plastic deformation rolling moderate strain (e = 1.6, where e true strain) structure undergoes fragmentation, which gives rise refining (the 8 ?m). Partial recovery recrystallization also occur. low-angle misorientation increases ?46%, decreases ?25%, compared state. yield strength this reaches 477 MPa elongation-to-failure 26%. combination °C 0.8) subsequent 600 0.7) reduces 1.4 ?m forms submicrocrystalline fragments. ?60%, ?3%. states formed provide an increase (yield 677 MPa) ductility values 12%. mechanisms strengthening under above treatments are discussed.