Relations of Counterface Hardness with Wear Behavior and Tribo-Oxide Layer of AISI H13 Steel

Dry sliding wear tests of AISI H13 steel (50 HRC) against AISI D2 steel counterface with three hardness levels (55, 50, and 42 HRC) were performed at 298 K to 873 K (25 °C to 600 °C). The relations of counterface hardness with the wear behavior and tribo-oxide layer of AISI H13 steel were explored. When sliding against the different-hardness counterface, H13 steel presents appreciably changed wear behavior as a function of temperature. For H _d/H _p (the hardness ratio of disk to pin) > 1, the wear rate increases with the increase of temperature, but the wear rate variation is roughly inversed for H _d/H _p < 1. For H _d/H _p = 1, the wear rate first decreases to reach the lowest value at 473 K (200 °C) and then rapidly increases with the increase of temperature. The lowest wear rate appears at 298 K (25 °C) for H _d/H _p > 1, at 474 K (200 °C) for H _d/H _p = 1, and at 673 K (400 °C) for H _d/H _p < 1. As no-oxide tribolayer exists below 473 K (200 °C), the wear behavior roughly complies with Archard’s equation; adhesive and abrasive wear prevail, regardless of H _d/H _p. As tribo-oxide layer exists at 473 K (200 °C) or above, the wear behavior depends on the tribo-oxide layer and thermal strength of the substrate, i.e., the stability of the tribo-oxide layer. Oxidative mild wear prevails at 473 K to 873 K (200 °C to 600 °C) for H _d/H _p < 1 and merely at 473 K (200 °C) for H _d/H _p = 1. However, a mild-to-severe transition of oxidative wear occurs at 473 K to 873 K (200 °C to 600 °C) for H _d/H _p > 1 and at 673 K to 873 K (400 °C to 600 °C) for H _d/H _p = 1. These findings suggest that the tribo-oxide layers are liable to exist stably for H _d/H _p ≤ 1 but to readily delaminate for H _d/H _p > 1.