Cryogenic Treatment Of 5a06 Aluminum Alloy Tig Welded Joints And Performance

Deep cryogenic treatment is a process used to enhance the strength and ductility of material. The process of deep cryogenic treatment has been used in some metallic material, to enhance the mechanical property and active time of component. It could also improve the stability of work-piece and the uniformity of material, non-polluting, and does not destroy the work-piece. It has positive prospects.Aluminum alloy with excellent performance is widely used in the welding structure, and it has become the ideal lightweight welding material. Aluminum alloy requires higher heat input in the welding, and high heat input easy generate welding deformations, residual stress, recrystallization of the welding zone and grain growth coarsening of the heat affected zone. So it will cause welding joints softened. Cast welding zone is easy to produce some welding defects (porosity, inclusion,etc).These defects will lead to reduce the strength of welded joint, thereby affecting the component performance. Therefore, we use deep cryogenic treatment process to improve the softening of aluminum alloy welding joints.In this paper,5A06 aluminum alloy TIG welding joints are studied,to study the effect of microstructure and mechanical properties of welding joints by deep cryogenic treatment. Study found that the process of deep cryogenic treatment improved the Brinell hardness, tensile strength, contraction of cross sectional area and extension percentage of the 5A06 aluminum alloy TIG welding joints; the Brinell hardness of welding joints gets the best improvement after deep cryogenic treatment at -175℃for 8 hours; Compared with non-cryogenic treatment, tensile strength of welding joints was increased up to 6.63% at -190℃for 12 hours after deep cryogenic treatment. The precipitate of the second phase was increased and significantly enhanced the relative intensity of X-RD diffraction peak in the welding zone after deep cryogenic treatment. And the ductility of the welding joints was improved after deep cryogenic treatment. Along with the deep cryogenic temperature reduced and the holding time elongated, the number of dimples gradually increased and the dimples became uniform and densification. So it improved the strength and ductility of 5A06 aluminum alloy TIG welding joints.Experimental results was analyzed, to study how to improve the softening of 5A06 aluminum alloy TIG welding joints by deep cryogenic treatment,and preliminary to analysis and discuss the mechanism of 5A06 aluminum alloy welding joints by deep cryogenic treatment.