Method of production of a high strength part

摘要

A high-strength part that excels in hydrogen embrittlement resistance and strength after high-temperature forming; and a process for producing the same. The atmosphere in a heating furnace before forming is regulated to one of ‰¤ 10% hydrogen volume fraction and ‰¤ 30°C dew point. As a result, the amount of hydrogen penetrating in a steel sheet during heating is reduced. After forming, there are sequentially carried out quench hardening in die assembly and post-working. As the method of post-working, there can be mentioned shearing followed by re-shearing or compression forming of sheared edge portion; punching with a cutting blade having a gradient portion at which the width of blade base is continuously reduced; punching with a punching tool having a curved blade with a protrudent configuration at the tip of cutting blade part, the curved blade having a shoulder portion of given curvature radius and/or given angle; fusion cutting; etc. Consequently, the tensile residual stress after punching is reduced and the performance of hydrogen embrittlement resistance is improved.