镍基单晶超合金中孔洞长大的试验和有限元分析

Experimental and Finite Element Study of Void Growth in Nickel-Base Single Crystal Superalloys

摘要:

在高温状态下，镍基单晶超合金的变形、损伤及断裂分析中，孔洞的长大都起着主要的作用。本研究进行了系列的蠕变、疲劳及热机械疲劳（TMF）试验。对试件的断面进行的SEM观察表明，所有的断面都是有许多小断面构成，在断面的中心，至少有一个孔洞。孔洞的尺寸与加载的条件相关。使用晶体塑性有限元程序对单胞模型进行分析，模拟孔洞的长大规律。给出了蠕变和弹塑性两种条件下的模拟结果及不同的晶体取向对孔穴长大的影响结果。对孔洞长大的有限元分析有助于对实验结果的理解。

Abstract:

Void growth behavior plays an important role in the deformation, damage and rupture of the nickel-base single crystal superalloys at high temperature. A set of creep, fatigue and thermal-mechanical-fatigue (TMF) experiments was carried out. The SEM observation on the fractured surfaces shows that for all experiments studied in this paper the fracture surfaces are made up of small facets. In the center of the facet, there is at least one void. The dimension of the void is dependent on the loading conditions. Crystallographic finite element method was applied to simulate the void growth by a cell model. Creep loading condition and plastic loading condition were modeled. The influence of the crystallographic orientations on the void growth was studied. The finite element study of the void growth can help to understand the experimental results.