为了研究Ni3Al基金属间化合物IC10高温合金的屈服行为,对其进行了不同加载路径下的双向拉伸试验.试验采用十字形双向拉伸试验件在Zwick/Roell Z010双向拉伸试验机上进行,得到的最大等效应变为0.02.试验加载方向与材料塑性各向异性主轴重合,采用位移控制方法让两个夹头的加载速率比保持不变,得到不同线性加载路径下的应力-应变曲线.根据单位体积塑性功相等原理获得了IC10合金在双向拉伸应力状态下的屈服轨迹,并与目前常用的几种正交各向异性屈服准则及von Mises屈服准则预测结果进行了对比.结果表明,IC10合金的试验屈服轨迹呈外凸性,以双向等拉线为界的上下部分屈服轨迹不对称,显示出明显的塑性各向异性.各向同性von Mises 屈服准则只包含一个材料常数,无法描述IC10合金的塑性各向异性行为;Hill 二次式屈服准则在双向等拉应力状态附近低估了材料的屈服强度;Logan & Hosford屈服准则在从双向等拉到横向单拉的应力状态下都低估了材料的屈服强度,与试验结果相差较大.Banabic-Balan屈服准则和Barlat (1989) 屈服准则的预测值与试验结果吻合很好,能很好地描述IC10合金在双向应力状态下的屈服行为.
Biaxial tensile tests of directionally solidified superalloy IC10 are carried out using cruciform specimens. The specimens are deformed under linear loading path on a Zwick/Roell Z010 biaxial tensile testing machine. The maximum equivalent strain attained is 0.02. The loading directions remain coaxial with the plastic orthotropy throughout every experiment. Contours of plastic work in the biaxial stress space are successfully determined and compared with the yield loci calculated from several existing yield criteria. It is found that the yield locus of superalloy IC10 is asymmetric about the balanced biaxial tension line, which indicates strong plastic anisotropy of the material. Von Mises yield criterion fails to describe the plastic anisotropy of IC10 since it contains only one material constant. Hill's quadratic yield criterion underestimates the measured work contours in the neighborhood of balanced biaxial tension. Logan & Hosford's yield criterion underestimates severely the measured work contours from the balanced biaxial tension to transverse uniaxial tension. Banabic-Balan's yield criterion and Barlat's yield criterion fit the data points well, which indicates it can describe the yielding behavior of superalloy IC10 under biaxial tension with good accuracy.
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