| Surfacing technology is an efficient and economical method to solve the problems of mechanical parts wear failure, while the wear resistance of deposited metal depends on the surfacing process. To study how the variation of welding process affects the wear resistance and to optimize the surfacing process by predicting wear resistance are significant and valuable in both scientific research and engineering. The most popular approaches to investigate wear resistance are wear test method and numerical simulation method. Comparing with the wear test'specimen method, by which the sample is difficult to manufacturing and the cost is too high, the numerical simulation method is rapid and economical, whereas the numerical model is hard to establish and the calculation accuracy is low relatively. Recently, the finite element method (FEM) and numerical simulation method (NSM) based on the theory of discretization of the continuous model are adopted to research the material wear by many scholars both domestically and exotic. Especially when combined with large commercial CAE software, these methods are famous for their intuitive construction mode, swift and powerful means for prep-post solver. However, the calculating results of the finite element model, which can only predict the wear trend, are deviating from wear test data.In this thesis, D172 electrode was deposited on the 45 steel with the thickness of 16mm by shield metal arc welding (SMAW) under different welding process. The microstructure and the chemical composition of the deposit metal were analyzed by optical microscope (OM), scanning electronic microscope (SEM), X-ray diffraction (XRD), and the micro-hardness was measured as well. The wear-resistance of the deposit metal was tested on the wear tester M-2000 on the condition of different loads and sliding distance. The wear mechanism was studied by analyzing the appearance of wear scars. In addition, the FEM calculating platform ANSYS/LS-DYNA was used to simulate the wear process and predict wear.The wear tests results indicate that:with the increase of welding current, the number of martensite were becoming less, the residual austenite and the carbide precipitation increased, and better-distribution in welding layer, the micro-hardness values decreased. The more surfacing layers are, the lower dilution effect of the base metal is. And the wear resistance of overlay surfacing materials was increasingly close to that of deposited metal. It can be conclude by analyzing the results of orthogonal test that:welding current, followed by sliding distance, load and layers of welding successively, is the most crucial affection factor to the wear-resistance. In the low-stress-and-speed mode, the wear volume increased as a respond to the increase of the welding current, the external load and the sliding distance, too. Contrarily, with the surfacing layers increase, the wear volume reduced. It can be summarized from the morphology of wear scar analysis that:the wear of deposited metal in the process of sliding friction is mainly the results that combining with the effects of adhesive wear, abrasive wear and oxidation wear. An explicit dynamic finite element model based on the calculation platform of ANSYS/LS-DYNA was established to simulate the sliding contact wear ring block. The calculating results show that with the increase of load, the wear volume increased in the same time correspondingly. It also can be observed from the wear loss curves that the wear rate (dm/dt) increased, which is equivalent to the results of wear tests approximately. However, the calculating results of FEM deviated from the wear test to some extent with respect to the analysis of wear volume variation, which is needed further research. |
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