Fine Grained Austenitic Stainless Steels : The Role of Strain Induced α' Martensite and the Reversion Mechanism Limitations

概要

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The effect of the α′-strain induced martensite on the austenitic stainless steel grain size reduction is analyzed. Rolling with a 80% reduction factor at 200°C and at 20°C resulted respectively in a heavily deformed austenite and a mixed deformed austenite with α′-martensite bands. Further annealing treatments were carried out in the range of 20–880°C. Fine grains of about 1 μm can be obtained in the metastable austenitic stainless steel by a repetitive cold rolling and annealing thermomechanical process. In this case, reversion mechanism from deformation induced martensite α′ to austenite γ is responsible for grain refining. Non-conventional warm rolling and annealing process can also lead to fine grains of 2 μm without a reversion stage and as a result of recrystallization process of the strain-hardened austenite. The cold rolling route gives rise to a bimodal grain size distribution with a “lamellar” structure resembling to a “composite” material.
社団法人日本鉄鋼協会の論文
2009-02-15