Effect Of Casting Process And Heat Treatment Process On The Microstructure And Mechanical Properties Of ZL210A Casting Aluminum Alloy

Al-Cu alloy is a typical high toughness casting aluminum alloy, which has high tensile strength, good corrosion resistance, strong toughness, it can be used for casting production complex shape parts, it has been widely used in aerospace, national defense science and technology. ZL210 A alloy is a new high strength casting Al-Cu alloy which developed by China foundry workers based on Russia BAЛ10 alloy which is suitable for domestic production status. ZL210 A alloy has no Ag and V rare metal, and the impurity limit is wider than ZL205 A alloy, so it has lower requirement for raw material,so it has very high economic value. However, ZL210 A alloy has less researched in domestic, so we don’t know very much about its performance characteristics and corresponding production process, it Production quality is not stable,especially in the actual production application, it has low elongation when ensure its high strength,sometimes the elongation is even lower than 1%, which severely limits the wide application of ZL210 A alloy. Therefore, carried out the experimental study on microstructure of ZL210 A alloy and optimized its mechanical performance, builting its scientific and reasonable casting process and heat treatment process, which has a very important significance for the large-scale production and application of ZL210 A alloy.In this paper, based on only sand mold and metal mold casting of ZL210 A alloy at present, developing ZL210 A alloy investment casting experimental, and conducted a comparative study; besides, systematic researched the different pouring temperature, the different effect of solid solution treatment and aging process on microstructure and mechanical properties of ZL210 A alloy, and carried on the thorough analysis of the mechanism of effect its microstructure and performance, the results are as follows:The grain size of investment casting is bigger than sand casting and metal casting,its average grain size is 176μm, there is a lot of network eutectic structure on grain boundary, and a large number of fine and dispersion T phase particle in the matrix,as-cast tensile strength, yield strength and hardness are respectively 187 MPa, 67 MPa and 60 HV, which are less than 198 MPa, 83 MPa, 61 HV of sand casting and 220 MPa,94MPa, 65 HV of metal casting, but the elongation of investment casting is 9%, which is same with metal casting, and higher than sand casting, which is 7%. so, ZL210 A alloy isalso suitable for investment casting.At different pouring temperature, the microstructure of as cast ZL210 A alloy is composed of equiaxed crystal structure of α(Al) matrix and intergranularα(Al)+θ(Al2Cu)+T(Al12CuMn2) eutectic microstructure and some coarse θ(Al2Cu)phase, with the increase of pouring temperature, ZL210 A alloy grains grow, the number of intercrystal eutectic increases, its mechanical properties decrease; when pouring temperature is 690℃, the tensile strength, the yield strength, hardness and elongation of ZL210 A alloy achieves the best value, respectively 199 MPa, 88 MPa, 70 HV and 8.5%.Through the research of solid solution temperature and solution time of ZL210 A alloy, we discovery when solid solution temperature and solution time respectively 540℃and 11 h, in ZL210 A alloy cu etc.solute atoms dissolved in α(Al) matrix reaching the saturation, as-cast coarse eutectic structure fully dissolved, the grain boundary is fine and smooth, a large number of small particles dispersed in the crystal, it is conducive to obtaining good solid solution, ZL210 A alloy has the best mechanical properties.Quenching temperature has certain influence on microstructure and mechanical properties of ZL210 A alloy, the grain size increases with quenching temperature increasing, precipitation phases constantly accumulate in grain boundary, developing bulk or needle like coarse structure, with the increase of quenching temperature,mechanical properties of ZL210 A alloy increase first and then decrease, when quenching temperature is 50℃, the mechanical properties of ZL210 A alloy is best.In addition, through the analysis of the size and morphology of precipitation phase of ZL210 A alloy at different aging temperature and time, we get the best aging process parameters for ZL210 A alloy, when aging temperature and time respectively 150℃and6h, we obtain the optimal combination of strength and ductility, the elongation of ZL210 A alloy improved significantly, improved the microstructure and mechanical properties of ZL210 A alloy.By using the optimized process parameters to do aging state experiment,guaranteed the elongation of sand casting can reach 8%, while its strength is not less than 417 Mpa, and guaranteed the elongation of metal mold casting can reach 9%, while its strength is not less than 431 Mpa, also guaranteed the elongation of investment casting can reach 6%, while its strength is not less than 415 Mpa.