Patent ID: 10533237

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° C. to 750° 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° C. to 1000° 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° C. or lower at a cooling speed of 20° C./s to 1000° C./s at the same time to manufacture an HPF part, [Expression 1] 190,000≤[coiling temperature (CT)×Time (min)]/2≤350,000, in the Relational Expression 1, Time refers to a time taken to reach 200° C. from coiling temperature.