单晶合金中孔洞对蠕变行为的三维有限元模拟  

Single Crystal Alloy on the Creep Behavior of Holes in Three-dimensional Finite Element Simulation

作　　者：张姝[1] 孟磊[2] 田素贵[3] 张建伟[1] 孟庆尧[1] 

机构地区：[1]沈阳化工大学机械工程学院,辽宁沈阳110142 [2]沈阳师范大学软件学院,辽宁沈阳110023 [3]沈阳工业大学材料科学与工程学院,辽宁沈阳110178

出　　处：《沈阳化工学院学报》2010年第1期52-57,共6页Journal of Shenyang Institute of Chemical Technolgy

基　　金：国家自然科学基金资助项目(50571070);辽宁省教育厅基金资助项目(2004C004)

摘　　要：通过对有/无缺陷单晶镍基合金蠕变性能测试、组织形貌观察及采用三维有限元对近孔洞区域的应力场分析,研究组织缺陷对单晶合金蠕变行为及组织演化的影响.结果表明:组织缺陷可明显降低单晶镍基合金的塑性和蠕变寿命.在高温蠕变期间,近孔洞区域的应力等值线具有碟形分布特征,并沿与施加应力轴成45°角方向有较大值,该应力分布特征可使合金中γ′相转变成与施加应力轴成45°角的筏状结构,并使圆形孔洞沿应力轴方向伸长成椭圆状.蠕变期间,在合金圆形孔洞缺陷的上、下区域具有较小的应力值,而在圆形孔洞的两侧极点处具有最大应力值;随蠕变时间延长,应力值增大,促使裂纹在该处萌生,并沿垂直于应力轴方向扩展,这是降低合金蠕变寿命的主要原因.Through the test of having defects creep properties of single crystal nickel-base alloy or not, the observation of morphology and the analysis of stress field near hole region by three-dimensional finite element. The investigation has been made into the influence of the defects on creep behaviors and micro- structure evolution of single crystal nickel-based superaUoys. The results show that the creep lifetimes and plasticity of the single crystal nickel based superalloys are obviously decreased by microstructure defects. During high temperature creep, the stress isoline near the holes region displays the feature of the acetabuli- form distribution, and possesses the bigger stress value at 45 ~ angle direction relative to the applied stress axis. That results in the γ phase transformed into the rafted structure at 45 ° angle direction relative to the applied stress axis, and the circular holes defects are elongated into the ellipse in shape along the direction parallel to the applied stress axis. During creep, a smaller value of the stress distribution displays in the up and down regions of the circular holes, and the maximum value of the stress distribution exhibits the apices region in the sides of the hole. In the further, the fact that the max value of the stress distribution increases as creep goes on results in the germination and expanding of the cracks, which is a main reason of dama- ging creep lifetimes of the alloys.

关 键 词：单晶镍基合金 孔洞 蠕变寿命 有限元分析 

分 类 号：TG132.2[一般工业技术—材料科学与工程]