| The application of aluminum alloys in automobile engine can effectively decrease structure-weight, while wear failure of piston groove is a critical problem for Al alloys. In this work, a surfacing layer with Ni35+Al powder by TIG arc was prepared on Al alloy in order to strengthen the surface with Ni-Al intermetallics.Orthogonal experiment was employed to optimize the TIG arc surfacing parameters. Taking formation quality of surfacing layer as the evaluating criterion, surfacing current, surfacing speed and thickness of preplaced powder could all influence the formation quality of Ni35+Al powder surfacing layer. The surfacing current could markedly influence the surface formation, as well as the thickness of powder could markedly influence the bonding quality.When Ni35+Al powder was surfaced with optimized parameters, with the increase of welding heat input and parameter combination, the penetration of surfacing layer increased while reinforcement height decreased; with the increase of thickness of preplaced powder, the reinforcement height increased accordingly.Two kind of characteristic microstructure was found in Ni35+Al powder surfacing layer: under weak parameter combination and high thickness of prepalced powder, the phases were Al3Ni+Al3Ni2+Al solid solution; under other conditions, the phases were Al3Ni+α-Al+Si With the increase of thickness of preplaced powder and the decrease of welding heat input and parameter combination, the amount of intermetallics increased accordingly.Prepared with optimized parameter, the hardness of Ni35+Al powder surfacing layer was improved from 66HV for base metal to more than 36HRC, while the weariness was 1/4 of that for base metal. With the increase of thickness of powder, the dilution rate decreased, and the amount of intermetallics increased accordingly. The hardness was 54.9HRC.
|
PDF Full Text Request