Wear behaviour of plasma nitrided steels at ambient and elevated temperatures

Abstract

The wear behaviour of plasma nitrided and white layer removed from AISI H13 and 722M24 steels were investigated at elevated temperatures. The samples prepared from the test materials plasma nitrided at 530–590°C for 4–100 h were tested at temperatures of 50–200°C under lubricated abrasive conditions. The wear behaviours of the samples are completely different in the test conditions from those observed at room temperature and dry conditions. It was observed that wear rate and surface roughness were decreased by the test temperature due to the softening of nitrided layer although the friction coefficients were increased under the test conditions. The removal of white layer produced during the plasma nitriding help the increase of wear resistance. On the other hand, abrasive particles in lubricant penetrate into the softer surface and protect the surfaces against abrasion. The solidified oil layer by the test temperatures also increased the wear resistance of the steels providing easy sliding.