| To study the effect of Al on the superplasticity of the ultra-high carbon steel (UHCS), 3-5%Al were added to the UHCS, and superplastic behavior has been measured at 700-800℃. To produce the fine and superplastic microstructure, an isothermal rolling at 700℃ was used, and the grain size of ferrite was less than about 2㎛ in diameter after the process. Significant improvement in superplasticity was observed ; the strain-rate sensitivity was high upto strain-rate of 1 × 10^(-2)s^(-1), and 535% elongation was measured at 750℃ when the engineering strain-rate was 500%/min(i.e., 8 × 10^(-2)s^(-1)). It has been analysed that the Al-addition lead to finer grain size, which, in turn, improved the superplastic properties of the ultra--high carbon steels. |
|
