| 摘要 |
PURPOSE:To allow superplasticity to appear by transforming martensitic phase into austenitic phase to form a fine dual-phase structure of these phases and exerting deformation at specific strain rate in a martensitic stainless steel at the time of or prior to hot working. CONSTITUTION:A steel composed essentially of Fe, Cr, and Ni and formed into martensitic single phase at ordinary temp. after annealing is cold-rolled at >=5% draft. Subsequently, this steel is heated up to a temp. in the region between [As point(the temp. at which transformation of martensitic phase to austenitic phase starts) + 30 deg.C] and Af point(the temp. at which transformation of martensitic phase to austenitic phase is completed) and not higher than 900 deg.C. By the above procedure, a fine and uniform dual-phase structure of martensitic phase and austenitic phase is formed, and deformation is carried out at 1X10<-5>/sec to 1X10<-1>/sec strain rate. |
