Effect of morphology of oxide scale on oxidation wear in hot working die steels

Wear tests under elevated-temperature air at 400 °C were conducted for H13 steel, H21 steel and the cast die steels. Structure and morphology of oxide scale were investigated by using XRD and SEM. XRD patterns for the worn surface of these steels exhibit that typical oxidation wear prevails. Two types of oxide scales were found to be single-layer and double-layer oxide scale, respectively. The single-layer oxide scale is characteristic of mild oxidation wear with lower wear rate. The appearance of double-layer oxide scale is attributed to obvious plastic deformation of oxide-underlying matrix. Double-layer oxide scale indicates an occurrence of the transition of mild wear to severe wear in oxidation wear.