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|1. (WO2015125422) HIGH-STRENGTH STEEL PLATE AND METHOD FOR PRODUCING HIGH-STRENGTH STEEL PLATE|
|Applicants:||JFE STEEL CORPORATION
|Title:||HIGH-STRENGTH STEEL PLATE AND METHOD FOR PRODUCING HIGH-STRENGTH STEEL PLATE|
Provided are: a high-strength steel plate having superior corrosion resistance after electrodeposition and chemical conversion treatment, even if a large quantity of Si or Mn is contained; and a method for producing the high-strength steel plate. During the continuous annealing of a steel plate comprising, by mass%, 0.03-0.35% of C, 0.01-0.50% of Si, 3.6-8.0% of Mn, 0.01-1.0% of Al, no greater than 0.10% of P, and no greater than 0.010% of S, the remainder comprising Fe and unavoidable impurities, in a heating step the temperature inside an annealing furnace is raised from a temperature region of 450-A°C inclusive (A being such that 500 ≤ A ≤ 600) at rate of temperature increase of at least 7°C/s, the highest temperature reached by the steel plate in the annealing furnace is 600-700°C inclusive, the transit time of the steel plate in the temperature region such that the steel plate temperature is 600-700°C inclusive is at least 30 seconds and no greater than 10 minutes, and the hydrogen concentration in the atmosphere is at least 20 vol%.