近代以來高強度異種材料之間的接合技術需求增加，硬焊製程是未來焊接工業中非常重要的方法，而本研究使用有限元素法模擬硬焊製程可能產生的熱應力與殘留應力，對於鈦合金與不同母材之間的硬焊製程進行研究，並與實驗結果相比對，結果顯示有限元素法的確可以做為硬焊實驗前的預測方法，預先了解熱膨脹係數差異所形成的殘留應力是否可能破壞焊道，減少實驗上不必要的花費。
硬焊殘留應力的形成源自於材料之間的熱膨脹係數不同，模擬結果顯示母材與焊道之間的殘留應力與材料本身關係較大，如熱膨脹係數差異小(如鈦合金與純鈮)的母材搭配，殘留應力雖然集中於焊道，但是並不足以破壞焊道，但是熱膨脹係數差異大(如鈦合金與304不鏽鋼)的母材搭配，焊道強度若是不足便會被殘留應力所破壞，所以需要使用強度較高的焊料。而小幅度改變工件形狀的設計並不會有效地影響殘留應力，改變焊料或是母材的搭配影響殘留應力較為明顯。

Brazing is one of the most important process to join two different materials together in industrial applications . In this thesis , finite element code ANSYS is adopted to investigate the transient distributions of temperature and stress during and after brazing process . Two typical cases are studied and analyzed . Moreover , distributions of residual stress are evaluated . It is found that the location of maximum von Moses stress is almost consistent to location of failure which shows that the simulation model can be used to estimate the availability of the specific brazing process .
It is found that transient and residual stresses are mainly attributed to the uniform distribution of temperature and mismatched coefficients of thermal expansion between two joined materials . For instance , the discrepancy in thermal expansion coefficients between Ti-6Al-4V and stainless steel is greater than that between Ti-6Al-4V and Nb . Consequently , the residual stress induced in the latter is smaller than the former . In addition , changes in the size and shape of two joined materials have little influence on the residual stress .

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