Unlubricated rolling/sliding wear behaviour of high silicon carbide-free steels

An investigation was carried out to examine the dry rolling/sliding wear behavior of high Si containing carbide free steel with respect to the austempering temperature and test cycles. Three batches of cylindrical disc specimens were prepared from an alloyed steel, 60Sicr7 and were austenitized at 820C for 30 min. Three different batches of samples were quenched in a salt bath maintained at 250,300 &350C respectively for 1h. Then the dry rolling/sliding wear tests were performed with each batch of samples for three different test cycles namely 6000, 18000 and 30000 cycles respectively to study the wear performance of these specific steels in the context of rail applications along with the in-depth microstructural characterization. The wear resistance was related to the total mass loss measured after the tests and the worn surfaces were analyzed by the scanning electron microscopy and X-ray diffraction techniques. Micro-hardness profiles were also obtained to analyze strain- hardening effects beneath the contact surfaces. The results indicate that the harder material exhibited lower wear rates for different test cycles i.e., the one austempered at 250C showed superior rolling/sliding wear resistance than the rest. It is also interesting to note that the hardness increment and thickness of the hardened layer is increasing with increase in the austempering temperature and number of test cycles.Validerat; 20101217 (root