钎焊接头的蠕变损伤与寿命预测

Investigation the Creep Damage and Life Prediction of the Brazed Joint

钎焊连接技术被广泛应用于航空航天、核电等领域的高效紧凑换热器制造中。高温高压工作条件下,蠕变及蠕变损伤引起的裂纹扩展是换热器中钎焊接头的主要失效方式之一。以高效紧凑换热器中常用的Inconel625/BNi-2及C276/BNi-2钎焊接头为研究对象,对其蠕变及蠕变裂纹扩展扩展行为进行了研究,获得钎焊接头的蠕变变形及裂纹扩展规律,澄清其蠕变及蠕变裂纹扩展失效机理。同时结合蠕变损伤本构模型和试验,对钎焊接头的蠕变损伤与寿命预测进行研究与综述,讨论钎焊工艺、扩散区性能及尺寸对钎焊接头蠕变裂纹扩展行为的影响规律,建立钎焊接头蠕变拘束参数,实现钎焊接头蠕变裂纹扩展行为尺寸效应的统一拘束表征,进而为基于材料-组件-装备一体化的寿命预测方法提供理论基础。

Brazing technology is widely used for manufacturing the high efficiency and compact heat exchanger applied in the fields of aerospace and nuclear power, etc. The creep and creep crack growth caused by the creep damage are one of the main failure modes for heat exchanger working at high temperature and pressure conditions. The Inconel625/BNi-2 and C276/BNi-2 brazed joint are adopted to investigate the creep deformation and creep crack growth behavior of the brazed joint, the creep deformation and crack growth characteristics of the brazed joint are obtained, and the creep failure mechanism of the brazed joint is clarified. Meanwhile, the creep damage and life prediction of the brazed joint are investigated and reviewed by using the creep damage constitutive model and experimental results. Based on the experimental and creep damage constitutive model analysis, effect of brazing technology, mechanical properties of diffusion zone and geometrical size on the creep crack behavior of the brazed joint are discussed, and the creep constraint parameter is proposed. At last, the size effect of creep crack growth behaviors for the brazed joint is successfully characterized by the creep constraint parameter. The life prediction method mentioned in present paper can provide the theoretical direction for the integrated life prediction from material-component to equipment.