STEEL PLATE FOR HOT FORMING AND MANUFACTURING METHOD OF HOT PRESS FORMED STEEL MEMBER

摘要

Provided is a method for manufacturing a steel member through hot press forming using a steel sheet that contains a comparatively large amount of Si. The method allows hot press forming to be carried out satisfactorily by stably and reliably suppressing shedding/peeling of oxide scale during hot press forming, even without restricting hot press forming conditions to a narrow range. The steel sheet includes, in mass ratio, C: 0.15% to 0.35%, Si: 1.0% to 3.0%, Mn: 1.0% to 3.0%, Al: more than 0% up to 0.10%, Ti: ([N]×48/14) % to 0.10% (where [N] denotes the amount of N in the steel sheet), B: 5 ppm to 50 ppm, P: more than 0% to less than 0.015%, S: more than 0% up to 0.010%, and N: more than 0% up to 0.010%, the balance being iron and unavoidable impurities. The average oxygen concentration from an outermost surface of the steel sheet down to a depth of 10 μm in a sheet thickness direction is 0.70 mass % or higher.

主权项

1. A steel sheet comprising, in mass ratio:
C: 0.15% to 0.35%; Si: 1.0% to 3.0%; Mn: 1.0% to 3.0%; Al: more than 0% up to 0.10%; Ti: ([N]×48/14) % to 0.10% where [N] denotes the amount of N in the steel sheet; B: 5 ppm to 50 ppm; P: more than 0% to less than 0.015%; S: more than 0% up to 0.010%; and N: more than 0% up to 0.010%, the steel sheet further comprising iron, wherein an average oxygen concentration from an outermost surface of the steel sheet down to a depth of 10 μm in a sheet thickness direction is 0.70 mass % or higher.