| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength steel plate excellent in chemical conversion, and corrosion resistance after electrodeposition coating even when having a large content of Si or Mn, and a manufacturing method thereof.SOLUTION: When a steel plate containing C of 0.03-0.35%, Si of 0.01-0.50%, Mn of 3.6-8.0%, Al of 0.01-1.0%, P≤0.10%, S≤0.010% by mass% and the remainder consisting of Fe and inevitable impurities is continuously annealed, the steel plate maximum arrival temperature in an annealing furnace is 600°C or more and 700°C or less, a steel plate passing time at a steel plate temperature of 600°C or more and 700°C or less is 30 seconds or more and 10 minutes or less, and a hydrogen concentration in the atmosphere is 20 vol% or more. |
