准静态加载下时效态Inconel 718薄板的各向异性屈服准则及硬化模型构建

当金属件的特征尺寸缩小到微尺度时,会产生尺寸效应,从而使对微成形的理解变得复杂。本文以0.1mm厚的时效态Inconel 718薄板为研究对象,对其进行了力学性能测试。基于力学测试数据,探究了时效态Inconel 718薄板在相同应变速率、不同拉伸方向上各向异性、延伸率、屈服强度及最大抗拉强度的变化规律,并建立了介微观尺度下各向异性及屈服强度的预测模型和考虑应变量及应变速率的准静态硬化模型。结果表明：时效态Inconel 718薄板具有明显的各向异性,其延伸率以45°为极值点呈现先增大后减小的变化规律,屈服强度和最大抗拉强度的变化规律与之相反。由于尺寸效应的存在需要两组不同的材料参数对各向异性及屈服强度进行预测。当应变速率大于0.1 s_^-1时,材料屈服强度表现出明显的应变速率敏感性,该硬化模型不再适用。

Anisotropic Yield Criterion and Hardening Model Construction of Aging Inconel 718 Thin Sheet Under Quasi-static Loading

The deformation mechanism will be more intricate by the size effect when the characteristic size of metal parts is reduced to a micro scale. In this paper, the aging Inconel 718 foil with thickness of 0.1mm was selected as the study subject and tested for its mechanical properties. Based on the data mechanical test, the anisotropy, elongation, yield strength and maximum tensile strength of aging Inconel 718 foils were explored under different tensile direction and uniform strain rate. And the predicted model of anisotropy and yield strength and the hardening model for considering the strain and strain rate are established. The research results show that the aging Inconel 718 foils have conspicuous anisotropy. The tensile direction of 45° is an extreme point for the anisotropy, elongation, yield strength and maximum tensile strength. The elongation and anisotropy firstly increase and then decrease with the increase of angle between tensile direction and rolling direction. But the change rule of yield strength and maximum tensile strength is opposite to elongation and anisotropy. In order to accurately predict the anisotropy and yield strength, two different sets of material parameters are needed due to the size effect. When the strain rate is higher than 0.1 s_^-1, the material yield strength shows obvious sensitivity for strain rate. In this moment, the above hardening model is not applicable.