| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength steel sheet plated with zinc by hot dipping which has excellent processability, which can be produced using a production line including zinc plating by hot dipping and in which a sufficient austempering time after annealing is not secured, without necessitating a special structural control as a pretreatment. SOLUTION: The high-strength steel sheet plated with zinc by hot dipping contains 0.05 to 0.3 mass% carbon, up to 1.4 mass% (including 0 mass%) silicon, 0.08 to 3 mass% manganese, 0.003 to 0.1 mass% phosphorous, up to 0.07 mass% sulfur, 0.1 to 2.5 mass% aluminum, 0.1 to 0.5 mass% chromium, and up to 0.007 mass% nitrogen, provided that silicon+aluminum≥0.5 mass%, with the remainder consisting of iron and unavoidable impurities. The steel sheet has a volume content of residual austenite of 3% or higher, and residual austenite grains have an average aspect ratio of 2.5 or lower. COPYRIGHT: (C)2007,JPO&INPIT
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