This paper presents an experimental evaluation of a viscoplastic constitutive model. The experiments conducted on a nickel-base superalloy, Inconel 718, include isothermal tensile, creep and cyclic tests at a high temperature of 650 deg C. The range of the examined strain rates is from 10~-7 s~-1 to 10~-3 s~-1. Negative strain rate sensitivie effect was observed between the strain rates of 1 x 10`-5 s~-1 and 1 x 10~-3 s~-1 during which plastic flow stress decreases as strain rate increases. Two creep tests were conducted. The data base is used for evalauting material parameters in the constitutive model. A modified model is proposed to simulate the negative strain rate sensitive behavior of the material. Comparison between experimental results and model predictions will be shown.
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机译：本文提出了粘塑性本构模型的实验评估。在镍基高温合金Inconel 718上进行的实验包括在650摄氏度的高温下的等温拉伸，蠕变和循环测试。所测试的应变速率范围为10〜-7 s〜-1至10〜 -3 s〜-1。在1 x 10`-5 s〜-1和1 x 10〜-3 s〜-1的应变速率之间观察到负应变速率敏感性效应，在此期间塑性流动应力随着应变速率的增加而降低。进行了两次蠕变测试。该数据库用于评估本构模型中的材料参数。提出了一种改进的模型来模拟材料的负应变率敏感行为。将显示实验结果与模型预测之间的比较。
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