Experimental investigation of the tribological behavior and wear mechanisms of tool steel grades in hot stamping of a high-strength boron steel

In this study, the high temperature wear behavior of hot forming tool steel grades is investigated by successive sliding of a pre-alloyed Usibor1500P® strip heated at high temperature. Experimental tests are performed at high temperature on an instrumented Deep-Drawing Process Simulator (DDPS). This laboratory pilot is employed to rank different steel grades used as tool materials in the hot-stamping process. The wear damage of the tool (die radius) is characterized by profilometry and SEM observations, and three quantitative criteria are determined from 2D profile measurements to assess adhesive and abrasive wear. Under examined conditions at high temperature, a predominant transfer mechanism is observed, while abrasive wear appears as minor damage. When the surface hardness of the tool material is not great enough, the sub-surface of the die radius can exhibit a plastic shear deformation of about 10 μm in depth. This leads to emission of wear debris coming from the cumulated cyclic plastic deformation of the sub-surface. In contrast, for high surface hardness, the adhesive wear rapidly reaches an asymptotic state.