Dynamic behavior of SUS304 stainless steel at elevated temperatures

An elevated temperature tensile impact experimental technique has been developed, using the rotating disk indirect bar-bar tensile impact apparatus with elevated temperature furnaces. Temperatures up to 800degreesC in the specimen have been obtained by means of rapid contact heating. Tensile impact experiments have been performed to investigate the mechanical behavior of SUS304 stainless steel in the temperature range 25-537degreesC. In contrast, the quasi-static tensions were conducted on MTS810 at three temperatures 25, 400 and 537degreesC, respectively. The experimental results show that the elevated temperature tensile impact experimental technique and method adopted are feasible practically. SUS304 stainless steel is a sort of temperature and strain-rate dependent metal, i.e., the strain rate has the effect of strengthening on yield stress and ultimate stress, but embrittling on unstable strain. The unstable strain decreases with increasing temperature at a constant strain rate, exhibiting an elevated temperature embrittlement phenomenon. The microstructure analysis reveals that the elevated temperature embrittlement phenomenon is due to the 'sensitization' of SUS304. In the case of impact loading, the adiabatic temperature rise is also capable of leading to sensitization. The differences of specimens' fractograph between tensile impact and quasi-static tension probably involve different deformation and fracture mechanisms. It is found that the volume fraction of gamma --> alpha' transformation is strain, temperature and strain-rate dependent. (C) 2004 Kluwer Academic Publishers.