POSCO Holdings Inc.
Method of manufacturing hot press formed parts having excellent powdering resistance

Abstract:

Provided is a method of manufacturing an HPF part comprising: preparing a steel sheet comprising C: 0.18% to 0.25%, Si: 0.1% to 1.0%, Mn: 0.9% to 1.5%, P: 0.03% or less, S: 0.01% or less, Al: 0.01% to 0.05%, Cr: 0.05% to 0.5%, Ti: 0.01% to 0.05%, B: 0.001% to 0.005%, N: 0.009% or less, and a balance of Fe and impurities; heating the steel sheet at 550.degree. C. to 850.degree. C. followed by maintaining at 640.degree. C. to 680.degree. C., and immersing the steel sheet in a hot dip aluminum plating bath, and a balance of Al and impurities; cooling the plated steel sheet at 15.degree. C./s or faster; heating the cooled hot dip aluminum plated steel sheet at 880.degree. C. to 930.degree. C. followed by maintaining for a certain time; and hot forming the alloyed hot dip aluminum plated steel sheet and quenching at a range of 300.degree. C. or lower at the same time.