Effects of welding materials on hot crack of spray formed 7475 Aluminum alloy in TIG welding joint

In this paper,the spry formed 7475 aluminium alloy was welded by TIG welding process with the welding consurnable 4043,5356 and 7055 respectively.The susceptibilities of hot cracking,as well as the mechanical properties,microstructures,the morphologies and the phase compositions of joints were studied in all three kinds of welding consumables.The results showed that susceptibility of hot cracking of welding material 5356 was closely related to the heat input.In condition of high heat input,Cu and Zn in parental material diffuse to weld and form low melting point eutectic phased α-Al,Al_0.403Zn_0.597 and Al₇Cu₃Mg₆ at fusion area with Mg from weld.And then they segregate at inter-granular and inter-dendrite.Therefore,penetrated hot cracks appeared in the fusion area under the action of welding stress.No crack appeared in condition of low heat input but the tensile strength of welded joint was only 184MPa.However,hot cracking susceptibilities of welding consumables 4043 and 7055 are relatively lower.