镍基单晶高温合金滑移系剪应力集中分析

Abstract

为了完善晶体滑移理论及基于该理论而发展起来的低周疲劳寿命模型、蠕变寿命模型在工程中的应用及评价，提出了镍基单晶合金滑移系剪应力集中系数的相关定义。通过理论推导和有限元方法分析了镍基单晶高温合金的滑移系应力集中系数，得到以下结论：1） 各向同性材料与镍基单晶合金的应力集中效应有着明显的差异，采用各向同性材料应力集中系数处理镍基单晶合金材料是不合适的；2） 对于平面问题，滑移系剪应力集中系数只决定于构件的形状、晶体方向、而与材料的弹性常数无关；3）对于镍基单晶合金材料，应力集中系数具有晶体取向各向异性。形状与载荷条件相同下，[111]取向具有最大的应力集中系数，[011]取向次之，[001]取向最小。 In order to perfect the crystal slip theory and its engineering application and evaluation of the low cycle fatigue and creep life model that developed on the crystal slip theory, the related definition of slip system shear stress concentration factor for nickel-based single crystal alloy was proposed .Through theoretical derivation and finite element method, the slip system stress concentration factor of nickel base single crystal superalloy was analyzed, it can be deduced that: 1) There exists obvious difference in stress concentration effect between isotropic alloy and nickel-based single crystal alloy. So it would be inappropriate to use the stress concentration coefficient of isotropic alloy to handle nickel-based single crystal alloy; 2) For plane problem, the shear stress concentration coefficient in slip system only determined by component’s shape and crystal orientation, and has nothing to do with the material elastic constants; 3) For nickel-based single crystal alloy, stress concentration coefficient is anisotropic with crystal orientation. Under the same shape and load conditions, stress concentration coefficient in [111] orientation takes its maximum, in [011] orientation second, and in [001] orientation the minimal.