含铸造微孔镍基单晶合金蠕变损伤和裂纹萌生的模拟计算  

Numerical Simulation on Creep Damage and Crack Initiation Behaviour of Nickel-Based Single Crystal Superalloys Containing a Casting Void

作　　者：温志勋 侯乃先 岳珠峰 

机构地区：[1]NW Polytech Univ, Dept Engn Mech, Xian 710072, Peoples R China

出　　处：《稀有金属材料与工程》2010年第11期1912-1917,共6页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(50905143,50775183);中国博士后科学基金(20090461310);“863”计划(2009AA04Z418)项目资助

摘　　要：基于镍基单晶合金蠕变变形过程中的细、微观组织结构变化及损伤特点,建立了考虑材质劣化和孔洞损伤的双参数蠕变损伤本构方程。利用所建模型对裂纹前缘含铸造缺陷(孔洞)的镍基单晶合金紧凑拉伸(CT)试样蠕变损伤和裂纹萌生进行了模拟计算,并考虑了晶体取向偏差和随机性的影响。计算结果表明:晶体取向和孔洞位置对试样蠕变损伤和裂纹萌生行为有着显著的影响。当孔洞距切口根部距离较近时,裂纹形核于切口附近的孔洞表面,裂纹形核时间较短;孔洞距切口根部距离较远时,裂纹形核位置位于切口表面,具体位置取决于试样的晶体取向,裂纹形核时间较长。随着加载轴晶体取向偏角的增大,裂纹形核时间明显缩短,其分散性加大,最大有34.7%的变化幅度;试样在2个不受控的晶体取向变化时,在偏角为45°和80°出现极值,裂纹形核时间最大偏差达3倍。Based on the meso- and micro-structure change and damage characteristic of Ni-based single crystal superalloys in the creep condition, a two-state-variable creep damage constitutive model considering simultaneously the rafting damage and void damage has been built. The model has been employed to investigate creep damage and crack initiation behaviour of the single crystal compact tension (CT) specimen containing a cylindrical void ahead of crack tip. The influence of the deviation and randomness of the crystallographic orientations has been considered. The analysis results have shown that creep damage and crack initiation behaviour depend strongly on the void location and crystallographic orientation. When the void is close to the notch root, a microcrack will initiate at the surface of the void in the vicinity of the notch. The time of crack initiation is short. But when the void is far from the notch root, the microcrack will initiate at the notch surface. The crack location is related to the crystallographic orientations, and the time of crack initiation is long. With increasing of the deviation of the axial crystallographic orientations of the single crystal CT specimen, the time of crack initiation is decreased obviously. The maximum amplitude variation is 34.7%. While the two uncontrolled crystallographic orientations of the CT specimens vary randomly, the time of crack initiation is longest in 45 degrees and 80 degrees deviations, and the maximum deviation of crack initiation time is up to 3 times.

关 键 词：铸造缺陷 微孔 镍基单晶合金 蠕变损伤 裂纹萌生 模拟计算 Single Crystal Crack INITIATION 裂纹形核 晶体取向 形核时间 孔洞损伤 试样 切口 位置 损伤本构方程 最大偏差 微观组织 损伤特点 取向偏差 

分 类 号：TG291[金属学及工艺—铸造]