فهرست مطالب سید امین ترابی

In this research, the effect of shot-peening treatment on the wear behavior of two types of high manganese austenitic steel (Fe-7Mn-0.6Si- 1.2C and Fe-17Mn-0.6Si-1.2C) was investigated. In this regard, two samples with various manganese contents of 7 and 17 weight percent are cast, respectively. In order to achieve a uniform structure of austenite into all samples, solution-annealing process is performed at temperature of 1100°C during 2h. Micro hardness measurement and tensile testing as well as wear test according to the rubber wheel-dry sand method are conducted on all heat-treated samples. Surfacing hardening treatment by using of shot- peening equipment is done during 15 and 30 mines on all samples. The results showed that when the percentage of manganese increased from 7 to 17% in the heat-treated samples, hardness and tensile strength values are increased and improved about 27% and 10%, respectively. The surface hardness of high manganese austenite steels is increased due to the applying surface work hardening with shot-pinning treatment. Thus, the highest hardness is observed in the shot-peened sample at time of 30 min. however, the highest hardness and wear %resistance are determined in the sample containing 7%Mn. The investigation of worn surfaces showed that the wear mechanism was abrasive mechanism. Moreover, the amount of and the depth of grooves are reduced with increasing of hardness values.

In this study, the wear behaviour of high-manganese- silicon austenitic steel with a nominal composition of Fe-17Mn-1.5Cr-6Si-1.2C with initial work hardening via shot peening were investigated. For this purpose, samples casted in sand moulds were solutionized annealing at the temperature of 1100 °C for 2 hours and then quenched in water. After that the samples were produced in the final shapes via wire cut machine. Initial work hardening was performed via shot peening of samples for 15 and 30 minutes. The hardness and wear behaviour was evaluation via the abrasive-wheel with dry sand. For microstructural analysis, the optical microscope and for evaluating the worn-out surface of the samples the scanning electron microscopy were used. Results show that increasing the period of shot peening improves the hardness from 368 to 661 and 748 HV in the 15 and 30 minutes peening respectively. Therefore, in the samples with higher hardness, the wear rate decreases (55%) and hence less weight loss is observed. Beyond this, the predominant wear mechanism was abrasive wear due to the parallel scratches on the worn-out surface of the samples. Initial work hardening, increases the hardness and hence number and depth of scratches decreases vividly.