Corrosion Behaviors And Tensile Properties Of Friction Stir Welding Joints Of High Strength Aluminium Alloys After Long-term Exposure Under Marine Atmospheric Environment

The microstructure of 2060 and 2A97 high strength aluminum alloy friction stir welding joints was characterized by metallographic microscope.The types of the second phase particles were analyzed by differential scanning calorimetry?DSC?.The size and distribution of the joints and their dissolution and precipitation behavior during welding were studied.The corrosion morphology and corrosion evolution of the upper and lower surfaces of high strength aluminum alloy friction stir welding joints exposed to offshore atmosphere were studied.The mechanical properties of high strength aluminum alloy friction stir welding joints after long-term exposure to offshore atmospheric environment were measured.Study on the effect of post welding heat treatment on two high strength aluminum alloy friction stir welding joints exposed for a long time The effect of corrosion behavior and mechanical properties.The structure of friction string welded joint of 2060 Aluminum Alloy analysis shows that the?'?Al₂Cu?,T₁?Al₂CuLi?phase in the weld nugget zone?NZ?and thermal mechanical affected zone?TMAZ?there is also a lot of GP zone and?'?Al₃Li?,the lowest hardness is TMAZ.The structure of friction stir welding of 2A97 NZ shows that the GP zone and a small amount of the existence of a large number of?'phase and T₁ phase;The BM,TMAZ,heat affected zone?HAZ?has a large number of T₁ and a few GP zone and?'phase,the lowest hardness is NZ,from NZ to BM hardness value is increasing.The corrosion behavior and tensile properties of the original joints show that the corrosion forms of the friction stir welding joints of the two high strength aluminum alloys in the welding state of the w 2060 and 2A97 are pitting corrosion,and the most serious corrosion zone is the heat affected zone.After long-term exposure,the hardness of 2060aluminum alloy friction stir welding joint was obviously improved except in the nugget zone,and the tensile strength and elongation of the friction stir welding joint were improved.The corrosion resistance of the friction stir welding joint of 2060 aluminum alloy was worse than that of the 2060 aluminum alloy friction stir welding joint.The hardness,tensile strength and elongation of the joints were decreased except in the nugget zone.The corrosion behavior and tensile properties of post-weld heat-treated joints show that the hardness and tensile properties of friction stir welding joints of two kinds of high-strength aluminum alloys,2060 and 2A97,have been greatly improved,but exposed to marine atmosphere for one year.The degree of corrosion on the surface of the joint is serious and the degree of corrosion is higher than that of the welded joint,and the overall tensile property of the joint is decreased,showing the ductile fracture without elongation.Post-welding heat treatment is not suitable for 2060 and 2A97 aluminum alloy friction stir welding joints used in marine environment.