PRODUCTION OF HOT-DIP ALUMINIZED STEEL SHEET EXCELLENT IN WORKABILITY AND CORROSION RESISTANCE

摘要

PROBLEM TO BE SOLVED: To produce a hot-dip aluminized steel sheet keeping the excellent corrosion resistance even after working without developing crack and defect such as detachment of plating even in the case of applying a severe working. ;SOLUTION: The steel sheet just before introducing into a hot-dipping aluminizing bath, is held at ≥630°C sheet temp. and the steel sheet is introduced into the hot-dipping aluminizing bath held at ≥640°C bath temp., and the hot-dip aluminized layer having 5-12 wt.% Si content is formed to both surfaces of the steel sheet at 100-350 g/m2 coating quantity per both surfaces, and the steel sheet pulled up from the hot-dipping aluminizing bath, is cooled to 400°C at ≥10°/sec average cooling rate and the obtd. hot-dip aluminized steel sheet is heated at 250-500°C for 5-50 hr. Since the alloyed layer developed on the interface between the hot-dip aluminized layer and substrate steel has a uniform layer thickness without developing projections, the crack and the detachment of plating as the starting point of development of the corrosion caused by the deformation of the hot-dip aluminized layer following to the working, are restrained.;COPYRIGHT: (C)2000,JPO