Influence of Cooling Conditions on Forming Performance of Hot Stamped and Press-Quenched Steel Sheet Part

Abstract

First, with a view of raising the operation rate of the press used in hot stamping and press quenching process, the influence of completion timing of press quench on shape quality and hardness property of the product was examined by an arc-shaped hot bending test with practical hot stamping steel sheet, and recommendable measures were suggested. In addition, by comparing the test results with those of austenitic stainless steel sheet without martensitic transformation, it was implied that good forming performance in the practical steel sheet was closely relating to its martensitic transformation. Then, in this connection, the influence of shape retaining force in the press quench operation on the shape quality was examined and the relevant features were revealed. Finally, with regard to the relation of the good shape quality in hot stamped and press-quenched steel sheet part with martensitic transformation, its mechanism was considered from the point of view of minimization of the internal work accompanying the anisotropic martensitic transformation with volume expansion.