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Al-7Si-Mg铸造铝合金的力学性能受凝固条件和热处理工艺参数的影响,如何建立各阶段工艺参数与微观组织、合金性能之间的定量化模型,对于优化工艺条件,提高合金性能具有重要的工程应用价值。建立了能够描述凝固、固溶处理和时效处理过程中微观组织演变的全过程、多尺度数值模型,并建立了相应强化模型,实现铸件最终屈服强度的预测。模拟了Al-7Si-Mg合金在各阶段的微观组织演变,并与实验结果进行了比较,分析了工艺参数对微观组织和合金屈服强度的影响规律。模拟和实验结果表明:二次枝晶臂间距随着冷却速率的增大而减小。Mg2Si颗粒的溶解和共晶Si的熔断在短时的固溶处理就可以完成。提高时效温度会促进时效析出,但会降低时效峰值强度,而增加Mg含量能够提高合金的屈服强度。最后分析了本模型存在的问题,指明该模型今后发展、充实与完善之处。
The mechanical properties of Al-7Si-Mg cast aluminum alloy are affected by the solidification conditions and the heat treatment process parameters. How to establish the quantitative model between process parameters and the microstructure and properties of the alloy at various stages is very important for optimizing the process conditions and improving the alloy performance Engineering application value. A whole-process and multi-scale numerical model was established to describe the microstructure evolution during solidification, solution treatment and aging treatment. The corresponding strengthening model was established to predict the final yield strength of the castings. The microstructure evolution of Al-7Si-Mg alloy at various stages was simulated and compared with the experimental results. The influence of technological parameters on the yield strength of microstructure and alloy was analyzed. Simulation and experimental results show that the secondary dendrite arm spacing decreases with the increase of cooling rate. The dissolution of Mg2Si particles and the melting of eutectic Si can be accomplished by solution treatment in a short time. Increasing the aging temperature will promote the aging precipitation, but will reduce the peak aging strength, while increasing the Mg content can improve the alloy yield strength. Finally, the problems existing in this model are analyzed, and the future development, enrichment and perfection of this model are pointed out.