WEAR AND SCRATCH HARDNESS OF 304 STAINLESS-STEEL INVESTIGATED WITH A SINGLE SCRATCH TEST

The wear and scratch hardness of 304 stainless steel was investigated with a scratch test developed by the US Bureau of Mines. The scratch was produced by a diamond indenter with a 0.2-mm spherical tip in air and in a corrosive environment. Scratch hardness was calculated from the width of the scratch and was correlated with Vickers hardness. Wear was measured by integrating the area between the profile of the scratch and the original surface. At low loads wear occurs in a rubbing mode. At higher loads wear debris was formed. The transition from rubbing wear to wear with a continuous formation of debris occurred at a critical value of the attack angle. A relationship between the attack angle, the radius of the tip of the scratcher, the load on the scratcher, and the hardness of the material is presented. Stainless steel was scratched at an anodic potential (with a passive film on the surface) and at a cathodic potential (with no passive film on the surface). The presence or absence of the passive film had no effect on the scratch hardness or wear for either the rubbing mode or the mode of wear with debris. The interface shear strength was not affected by the change in potential.