Elucidation of interfacial microstructure inhomogeneity and crack defects of laser fusion-brazing AA5083/TA31 dissimilar butt joints at different groove angles

卷:126

Article

关键词: MECHANICAL-PROPERTIES;    ALUMINUM-ALLOY;    OFFSET;   

DOI  :  10.1007/s00170-023-11372-7

来源: SCIE

【 摘 要 】

Al/Ti dissimilar alloy plates with a thickness of 6 mm were butt joined using the direct laser fusion-brazing method. A systematic comparison of laser fusion brazing of four groups of AA5083 to TA31 plates with different groove angles ranging from 60 to 90 degrees was performed by laser beam offsetting to the aluminum alloy side. The related weld appearance, microstructures in the weld and at the joint interface, defects formation mechanism, and fracture resistance were analyzed and compared in detail. A preferable joint appearance characterized by wetting the top and bottom sides of the titanium alloy with molten aluminum alloy can be obtained except for the joints with 60 degrees groove angle. The uniformity of intermetallic compound (IMC) morphology and thickness distribution at the interface was improved as the groove angle decreases, accompanied by a decrease in the diffusion distance of main elements at the same location. Severe interfacial crack and intergranular hot crack defects were formed in the joints with 90 and 60 degrees groove angles, respectively. The interfacial cracks are induced by the difference in hardness and elastic modulus between TiAl3 phases and titanium base metal or aluminum weld. The hot crack defects are mainly caused by microstructure mismatch including grain size and texture orientation mismatch between the fine grain zone near the interface and the coarse grain zone inside the aluminum alloy weld. The crack-free joints with groove angles of 70 degrees show the highest tensile strength of 268.76 MPa due to the relatively uniformly distributed and fine interfacial IMCs. This study reveals the possibility to realize efficient joining of medium-thick titanium alloy and aluminum alloy plates by using the laser fusion-brazing method without other auxiliary equipment.

【 授权许可】

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