| SUS304 austenitic stainless steel was deformed by high pressure torsion (HPT) at room temperature at different the rotation speed. By using X-ray diffraction (XRD) and transmission electron microscopy (TEM), the quantitative phase analysis and microstructural evolution along the progress of HPT were investigated. The present results show that the deformation-induced dynamic phase transformation (DPT) not only from austenite (γ) to martensite (α') but also α' to γ occurred and equaixed nanocrystalline γ grains are generated by HPT at high rotation speed. It is proposed that in austenitic stainless steel nanocrystalline γ grains structure is formed by combination of forward (γ → α') and reverse (α' → γ) DPT induced by HPT at high strain rate. |
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