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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.
The creep behavior and microstructure of the single crystal nickel-base alloy with / without defects were observed, and the stress field analysis of the near-hole region by three-dimensional finite element method was used to investigate the effect of the microstructure defects on the creep behavior and microstructure evolution of the single crystal alloy. The results show that the microstructure defects can obviously decrease the plasticity and creep life of single crystal Ni-base alloys.During the creep of high temperature, the stress contour of the near-hole region has a dish-shaped distribution and forms a 45 ° angle along the applied stress axis The direction of the larger value, the stress distribution characteristics of the alloy can be transformed into γ ’phase with the stress axis at a 45 ° angle of the raft-like structure, and the circular hole along the stress axis elongated into an oval shape during creep , Which have smaller stress values in the upper and lower regions of the circular hole defects of the alloy and the maximum stress values at the poles on both sides of the circular hole. As the creep time prolongs, the stress value increases, prompting the crack to occur there Initially, and along the direction perpendicular to the stress axis expansion, which is to reduce the alloy creep life of the main reasons.