| To find out the critical strain value for recrystallization, strain distribution in cylindrical specimen after hot compression test was simulated by Finite Element Method(FEM) and evaluated by observing the microstructure of hot compressed specimen. FEM analysis results show that effective strain distribution depends on the position in specimen. Core and edge region of specimen shows higher effective strain than other region. Especially the magnitude of strain at core is twice larger than the mean strain value. Mode of effective strain distribution also changed with the magnitude of applied strain and localized phenomena. In hot compression test, the shape change in barreling region and recrystallized state of austenite grains were investigated. The calculated result of strain distribution and microstructure observation result of austenite were correlated to find out the critical strain for recrystallization of austenite, because the shape of hot compresses specimen was well coincident with that of FEM calculation. In case of 304 stainless steel, 17% strain was required was for recrystallization at 1050℃. For practical application, one or two hot compression test instead of dozen of hot compression tests is enough to obtain the critical strain for recrystallization by simulating the strain distribution in specimen. |
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