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When laser cladding is used to repair parts, the interaction of parameters has a significant influence on equipment performance. In order to explore the process parameters and quality of Ni60PTA coating, the statistical relationship between the process parameters (laser power, scanning speed, and powder feeding rate) and the responses (dilution ratio, ratio of layer width to height, and contact angle) was established by experiments using the response surface method (RSM) and variance analysis. The results show that the laser power is the dominant factor affecting the dilution ratio. However, the scanning speed has the greatest influence on the ratio of layer width to height and contact angle. These experimental results show that the proposed model can predict the actual data. In addition, the microstructure and microhardness of the samples prepared with the optimum process parameters were characterized. The results show that the quality of the cladding layer is good without cracks, deformation, and pores. The microstructure of the cladding zone is mainly composed of γ (Ni), FeNi3, M (M = Fe, Ni, Cr)23C6, M7C3, and CrB. The average microhardness of the coating is about 620 HV0.2, which is about 3.1 times that of 45 steel substrate.

Rail-switches are key parts of rail structure and necessary line facility by which trains can change from one route to another. With the pick up speed of trains, mayor parts of rail-switches wear severely. It is very important to seek a new method or technique to raise the wear-resistant properties of switch material (high manganese steel). We do some experiments with cold rolling on austenitic high manganese steel by the asynchronous rolling technique, and study its performance after rolling. The results show that strain-hardening and impact abrasion resistance are enhanced greatly with the increase of deformation.