1. Forgings Quality TeamPOSCO Specialty Steel Co., Ltd, 65 Shinchon‐dong, Changwon, Kyungnam 641‐370, Korea
2. Materials Deformation GroupKorea Institute of Materials Science, 531 Changwondaero, Changwon, Kyungnam 641‐831, Korea
3. Engineering Research Center for Net Shape and Die ManufacturingPusan National University, San 30 Jangjeon‐dong, Geumjeong‐gu, Busan 609‐735, Korea