Published online by Cambridge University Press: 16 February 2011
To study the effect of Al on superplasticity of ultra-high carbon steel (UHCS), 3–5%Al was added to the UHCS, and superplastic behavior was measured at 700–800°C. To produce the fine and superplastic microstructure, an isothermal rolling at 700°C was used, and the grain size of ferrite was less than about 2μm in diameter after the process.
Significant improvement in superplasticity was observed; the strain-rate sensitivity was high upto a strain-rate of 10−2 s−1, and 402% elongation was measured at 750°C and at an engineering strain-rate of 5000%/min(i.e., 8.3×10−2s−1). It has been determined that the Al-addition leads to a finer grain size, which, in turn, improved the superplastic properties of the ultra-high carbon steels.