粉末高温合金粘塑性试验评定与本构模型参数估计

EVALUATION OF VICSO-PLASTICITY OF POWDER METALLURGY SUPERALLOY BY EXPERIMENT AND ESTIMATION OF CONSTITUTIVE PARAMETERS

开展了粉末高温合金 FGH95 5 5 0℃、60 0℃和 65 0℃等 3种温度下控制应变率单向拉伸试验和 5 5 0℃下循环加载试验研究 ,结果表明 :60 0℃以下 ,快、慢应变率时 ,5 %的试验应变范围内应力—应变曲线都一直上升 ,不存在应力饱和现象 ,热恢复效应不显著 ;但 65 0℃下慢应变率时则存在较明显的应力饱和现象 ,反映出在此条件下必须考虑蠕变效应。温度越高应变率对 FGH95的拉伸力学性能影响越明显 ,但总的说来是一种应变率不甚敏感的循环硬化材料。最后 ,在试验的基础上建立了 FGH95的 Bonder-Partom统一弹 -粘塑性本构模型 ,理论与试验吻合较好 ,表明该模型能够模拟 FGH95的应力 -应变关系曲线、应变率响应特性以及循环硬化特性 ,从而为 FGH95粉末高温合金构件的高温应力分析打下了基础。

This paper performed straining rate controlled uniaxial tension tests of FGH95 powder metallurgy superalloy at 550℃, 600℃ and 650℃. The cyclic loading test at 550℃ was also made. The results show that when the test temperature is less than 600℃ the stress strain curves display an ascending trend without stress saturation and the thermal recovery is not remarkable. At 650℃, there is obvious stress saturation under slow straining rates, and the creep effect must be considered. FGH95 is a kind of cyclic hardening material, which is slightly sensitive to the straining rate. Finally, the Bonder Partom constitutive model parameters are evaluated on the basis of the above test curves. The theoretical results are accordant to the experiment. The Bonder Partom constitutive model can simulate the stress strain curve, the straining rate and cyclic hardening characteristics of FGH95. The paper provides a base for the stress analysis of powder metallurgy superalloy components under high temperature.