SHEARING PART HARDENING METHOD, STEEL MATERIAL HAVING HARDENED SHEARING PART, AND MANUFACTURING METHOD FOR STEEL MATERIAL HAVING HARDENED SHEARING PART

摘要

PROBLEM TO BE SOLVED: To provide a shearing part hardening method for excellently hardening a shearing part formed in a steel material even if a DI value of the steel material is low.SOLUTION: A shearing part hardening method includes: a heating step of heating a steel material so as to raise a temperature of the steel material to a temperature equal to or more than an austenitizing temperature; a shearing step of shearing the steel material while keeping a temperature of the steel material heated in the heating step in a temperature equal to or more than an austenitizing temperature so as to form a shearing part on the steel material; and a cooling step of cooling the steel material so as to lower a temperature of the steel material formed with the shearing part in the shearing step to a temperature equal to or less than a martensite point.SELECTED DRAWING: Figure 11