On the influence of retained austenite in the abrasive wear behaviour of a laser surface melted tool steel

In this work, the influence of the proportion of retained austenite in the abrasive wear resistance of a laser surface melted martensitic stainless tool steel is analysed. Samples of a 0.5 wt.% C, 13 wt.% Cr+Fe martensitic stainless tool steel were surface melted using a CW CO2 laser. By changing the processing parameters, samples with proportions of retained austenite varying from 15 to 100% were produced. Microscale abrasive wear tests were performed in the samples. The wear behaviour of the laser melted samples was compared with that of a sample of the same steel in the conventional quenched and tempered condition. It was observed that the wear behaviour of the material depends on the proportion of retained austenite but also of the test conditions, namely of the applied load. For the lower test loads, it was observed that the material submitted to conventional heat treatment presents higher wear resistance; on the contrary, for the higher test loads, it was observed that some of the laser melted samples present a wear resistance higher than that of the conventionally treated material. The analysis of the worn surfaces shows that, in the laser surface melted samples, the stress-induced transformation of austenite into martensite plays an important role in the increase of the wear resistance of the material with increasing applied load. (C) 2004 Elsevier B.V. All rights reserved.