6063/Ti3Al2.5V异种合金激光熔钎焊接头组织及力学性能研究
毕业论文关键词：铝合金，钛合金，激光熔钎焊，焊缝成形，力学性能，组织物相
Abstract The composite welding structure of aluminum alloy and titanium alloy is widely used in the aerospace and automotive industries because of its performance advantage which combine the advantages of both alloys together. However, the base materials of Al and Ti have a great difference in physical and chemical properties and the difference will influence the dissimilar alloy’s welding joints greatly, which will reduce the joint quality seriously. So control the intermetallic compound produced by the reaction of Al/Ti dissimilar alloy welding is the biggest problem of Al/Ti dissimilar alloy welding. This paper uses laser penetration brazing to joining the 6063 aluminum alloy with 5mm thickness and the Ti3Al2.5V titanium alloy with 5mm thickness. During the welding process, when the laser acts on the surface of Al alloy the laser melted a side of the aluminum alloy. Then the liquid aluminum alloy spread on the surface of Ti alloy, forming an effective laser welding brazing welded joints of Ti/Al dissimilar alloy. When the laser acts on the surface of Ti alloy. Al alloy is melted by heat conduction from the middle solid Ti layer. Then the liquid aluminum alloy spread on the surface of Ti alloy form an effective laser welding joints. In the experiment, the shape of the molten pool and the thickness of the middle solid Ti layer in the interface can be controlled by adjusting the beam offset, beam deflection angle. The microstructures in the joint are studied by using Optical Microscopy, scanning electron microscope, EDS and XRD. Joint mechanical property was measured by tensile test and hardness test. The test results show that when the laser acts on the surface of Ti alloy, the process parameters were 4000W of the laser power, 0.8mm to 1.0mm between the laser beam offset, 5°deflection angle of the laser beam and 1.2m/min of the speed of welding, the appearance of weld is perfect. When the laser beam offset is 0.8mm, the joint’s maximum tensile strength is 132.8MPa. From the analysis of the joint’s microscopic structure, intermetallic compounds was likely to be AlTi,AlTi3,Al2Ti and Al3Ti。