Al-7Si-Mg铸造铝合金拉伸过程应力-应变曲线和力学性能的模拟

Modeling the Stress-Strain Curve and Mechanical Properties During Tensile Process in Al-7Si-Mg Cast Aluminum Alloy

屈服强度、抗拉强度和伸长率是Al-7Si-Mg铝合金铸件常用的力学性能评判指标,因此建立相应的定量化模型进行拉伸力学性能的预测具有重要工程应用价值。本文建立了时效析出动力学、屈服强度、应变硬化模型,模拟Al-7Si-Mg合金在拉伸过程的应力-应变曲线和相应的拉伸力学性能。针对Al-7Si-0.4Mg合金,开展相应的实验研究,获得不同时效工艺下的拉伸应力-应变曲线以及力学性能数据,归纳出σUTS-σY与σY之间的关系式。模拟了该合金在180℃时效条件下屈服强度、抗拉强度和伸长率随时效时间的变化规律并进行实验结果对比,同时分析了时效工艺对合金应变硬化的影响规律。

The tensile properties including yield strength, ultimate tensile strength and elongation are commonly used to judge the mechanical properties of castings in Al-7Si-Mg alloys, thus establishing the quantitative models to predict the tensile properties plays an important role in the engineering application. The paper presents the precipitation kinetics model, yield strength model and strain hardening model in order to predict the stress-strain curve and further the tensile properties in Al-7Si-Mg alloys. Corresponding experiment was carried out for Al-7Si-0.4Mg alloy to acquire the stress-strain curves and the tensile properties after aging for different time, and further to generalize the linear relationship between σUTS-σY and σY for the under-age and peak-age samples. Using these models, the yield strength as a function of aging time at 180 ℃ was predicted and compared with the experimental results. The influence of precipitate microstructure parameters on yield strength was analyzed. Using the strain hardening model, the stress-strain curve after yield strength is calculated and is also compared with the experimental measured ones. Through combining the calculated stress-strain curve with the relationship between σUTS-σY andσY, the ultimate tensile strength and elongation is also predicted and compared with experimental values.