Wear characteristics of austenitic steel and martensitic steel at high temperature

Wear under high temperature is one of the mechanisms of die failure. Therefore, wear resistance at high temperature is an important parameter for selecting die materials. In this work, the wear resistance of SDHA austenitic steel (6Mn14Cr3Mo2Si1V2 steel) and 4Cr5Mo2V martensitic steel at 400 degrees C-700 degrees C was investigated using a friction and wear tester. The wear behaviour and oxide type were investigated using a scanning electron microscope (SEM) and by X-ray diffraction (XRD), respectively. The results show that the oxides on the worn surface at the test temperatures are Fe2O3 and Fe3O4. With increasing test temperature, from 400 degrees C to 700 degrees C, the wear volume of the two steels initially decreases and then increases. Between these two temperatures, the wear volume of SDHA austenitic steel increased from 29.7 mm(3) to 81.2 mm(3), a 173.4% increase. The wear volume of 4Cr5Mo2V martensitic steel increased from 34.7 mm(3) to 134.7 mm(3), a 267.4% increase. Hence, SDHA austenitic steel has better wear resistance than 4Cr5Mo2V martensitic steel. This is attributed to excellent hardness stability at high temperature. The coarse M7C3 carbides in 4Cr5Mo2V martensitic steel cause peeling and delamination of the oxide layer, reducing wear resistance at 700 degrees C.