54 巻 (2013) 627 号 p. 343-347
A 1 shot hot stamping process of ultra-high strength steel parts consisting of rapid resistance heating, forming, shearing and die quenching was developed to eliminate an additional quenching process. A rectangular sheet was resistance-heated to obtain a uniform distribution of temperature, and immediately after the end of heating a sequence of forming, shearing and die quenching was performed by 1 shot to prevent the drop in temperature. An ultra-high strength steel spur gear having a hardness of 540 HV2 was produced by the 1 shot hot stamping consisting of the heating, blanking and die quenching. The surface of the sheared edge of the produced gear was almost burnished, whereas the rollover became comparatively large. An ultra-high strength stainless steel part having a hardness of 580 HV2 was produced by the 1 shot hot stamping consisting of the heating, bending, shearing and die quenching, and no springback and quenching distortion of the produced part were observed by holding at the bottom dead center of the press.