Experimental Research On Fatigue Failure Of Tig Welded Joint In Aluminum Alloy Plate-Fin Heat Exchanger

Aluminum alloy heat exchanger is a kind of industrial product widely applied in modern society. Because of excellent thermal conductivity, lightweight, economical efficiency, aluminum alloy heat exchanger is replacing copper and stainless steel ones step by step. Following with the developments of novel design for high-dense, small gravity, high-pressure and high corrosion resistance, the more critical demanding of the quality of welded joint in Aluminum alloy heat exchanger is proposed.In this dissertation, based on the fracture failure of performance tests of 320C Al alloy heat exchanger, several reasons were analyzed. The number of cycles under certain pressure was obtained through pressure cycle tests of the heat exchanger. The main reason of fracture failure was found that the welded joints were subjected to the excessive tensile stress by the fracture analysis, macroanalysis, microstructure analysis and stress simulation. Meanwhile stress concentration of root of weld caused by faulty fusion and many porosities of welded joint were the reasons of fracture as well.Through the improvement of structure and welding procedure of the heat exchanger, the stress of root of weld was reduced extremely and the weld defects were under control. At last the performance of the product reached the demand of company.The study on fatigue is very important for the base metal and welded joint in the heat exchanger. In this dissertation the fatigue curves of base metal and welded joint were gained. The fatigue curves are very significant for the design and prediction of products for the future.