POSCO Holdings Inc.
Hot press forming parts having excellent bending properties and method for manufacturing the same

Abstract:

Provided is a method for manufacturing an HPF part having excellent bending properties including: manufacturing a hot rolled steel sheet; coiling the hot rolled steel sheet within a range of 450.degree. C. to 750.degree. C. for a time satisfying Expression 1; cold rolling, annealing and then hot dip aluminum plating on the annealed steel sheet; heating the hot dip aluminum plated steel sheet to a temperature of 850.degree. C. to 1000.degree. C. and maintaining the hot dip aluminum plated steel sheet for a certain period of time; and hot forming the heated steel and cooling at a temperature within a range of 200.degree. C. or lower at a cooling speed of 20.degree. C./s to 1000.degree. C./s at the same time to manufacture an HPF part, [Expression 1] 190,000.ltoreq.[coiling temperature (CT).times.Time (min)]/2.ltoreq.350,000, in the Relational Expression 1, Time refers to a time taken to reach 200.degree. C. from coiling temperature.