| 摘要 |
PROBLEM TO BE SOLVED: To provide a stainless steel sheet having high strength, and excellent in workability, and excellent in fatigue properties and corrosion resistance in the worked part, and to provide its production method. SOLUTION: At least in the region within 3μm to the sheet thickness direction from the sheet surface, nitrogen compounds with a grain size of 10 to 200 nm are allowed to exist by≥200 pieces per 100μm<SP>2</SP>. In this case, the number of the nitrogen compounds with a grain size of 10 to 200 nm in the region within 3μm to the sheet thickness direction from the sheet surface is controlled to≥2 times compared with the number of nitrogen compounds with the above size in the central part of the sheet thickness. Simultaneously, the grain size number of a matrix in the region within 3μm to the sheet thickness direction from the sheet surface is controlled to the one larger than the grain size number of a matrix in the central part of the sheet thickness by≥1. Thereby, its strength and workability are secured. In its production, a stage (1) where annealing is performed in the temperature range of 1,000 to 1,200°C for≥20 sec in an atmosphere comprising nitrogen of≥5 vol% and having a dew point of≤-40°C, and a stage (2) where, after the above heat treatment, annealing is performed at a temperature lower than the above heat treatment temperature by≥50°C, are carried out. COPYRIGHT: (C)2006,JPO&NCIPI
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