- Al-Fe coated steel sheet having good hydrogen delayed fracture resistance property anti-delamination property and spot weldability and HPF parts obtained therefrom

摘要

Provided are an aluminum-iron alloy plated steel sheet for hot-forming, having an excellent hydrogen delayed fracture resistance property, anti-delamination property, and spot weldability, and a hot-forming member using the same. In regard to an alloying aluminum plated steel sheet, having an alloying plated layer formed between a matrix steel sheet and an oxide layer, the matrix steel sheet comprises: 0.1-0.5 wt% of C; 0.01-2 wt% of Si; 0.01-10 wt% of Mn; 0.001-0.05 wt% of P; 0.0001-0.02 wt% of S; 0.001-1.0 wt% of Al; 0.001-0.02 wt% of N; and the remaining of Fe and inevitable impurities. The alloying plated layer includes: an Al-Fe alloying layer (I) formed on the matrix steel sheet with 200-800 Hv of Vickers hardness; an Al-Fe alloying layer (III) formed on the alloying layer (I) with 700-1200 Hv of Vickers hardness; and an Al-Fe alloying layer (II) consecutively or not consecutively formed inside the Al-Fe alloying layer (III) in a longitudinal direction of the steel sheet with 400-900 Hv of Vickers hardness. The oxide layer contains not more than 20 wt% of oxygen averagely in a spot at a depth of 0.1 m from its surface.