Abrasive Wear in Punching Pin with Cryogenic Treatment for GPa-Grade Steels

The increasing application of GPa-grade steel to autobody panels has led to increasing problems related to abrasive wear in mold and tool surfaces, which dramatically degrades tool life and also degrades the surface finish of the final product. This paper mainly concerns the punching wear resistance imparted by cryogenic (CR) and quenching and tempering (QT) treatments, as well as the additional use of a TiN coating layer. This is investigated using pin-on-disk tests and punching experiments against DP980 sheets for up to 90,000 cycles. The wear coefficient of CR is about 10% greater than that of QT, which leads to a decelerated punching pin wear rate relative to QT starting at around the 70,000th cycle. To numerically predict abrasive wear, we newly propose that the wear coefficients of the substrate should be updated as a function of the clearance stage to improve the accuracy and efficiency of the wear analysis.