STEEL SHEET AND MANUFACTURING METHOD THEREOF, AND METHOD FOR MANUFACTURING PARTS WITH EXCELLENT SHA

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PROBLEM TO BE SOLVED : To provide a method for manufacturing parts having minimal spring back after forming, high precision, high strength after forming and excellent shape fixability. SOLUTION : A steel sheet which has a composition containing properly regulated amounts of C, Si, Mn, P, S and Al, containing 0.0050 to 0.025% N and ≥0.0030% N in a solid-solution state, further containing V or further either or both of Nb and Ti, and containing ≥0.03%, in total, of V or further Nb and Ti in a solid-solution state and also has a structure having ≤10μm average grain size is used. This steel sheet is subjected to working where plastic deformation of ≥2% average amount of strain is performed at 200 to 700°C at an average strain rate preferably of 1/s and above. Further, one or more elements among Cu, Ni, Cr and Mo and/or either or both of Ca and REM (rare earth metal) can be contained. COPYRIGHT : (C)2006, JPO&NCIPI