日本金属学会誌

J. Japan Inst. Metals, Vol. 39, No. 4 (1975),
pp. 357-361

Transformation Superplasticity in the Commercial Low Carbon Steels under Rapid Heating

Nobuhiro Iguchi, Yoshiki Oka and Yasunori Saotome

1Faculty of Science and Engineering, Waseda University, Tokyo
2Graduate School, Waseda University, Tokyo

Abstract:

The transformation superplasticity occurs depending not on the factor of micro-fine structure required in the micro-grained superplasticity but on the factor of the transformation proceeding under the applied stress. In this report the effects of heating rates upon the transformation superplasticity generated during the ithothermal process were investigated in the low carbon steels with the same method done for pure iron in the previous paper.
The main results obtained are as follows.
(1) The transformation superplasticity in the low carbon steels occurred in the range of 750 to 1050°C under rapid heating (the heating rate: 35 ∼ 100°C/sec).
(2) The linear law between the applied stress τ and the total strain γ per cycle was recognized within τ=0.6 kg/mm.
(3) The flow curves induced by the transformation superplasticity were determined at each heating rate. The value of the strain rate sensibility m was about 1.
(4) The transformation superplasticity was not observed in the A1∼A3 point ( α+γ ) region during the isothermal process.


(Received 1974/09/11)

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