焊接材料对喷射成形7475铝合金TIG焊接头热裂纹的影响

采用4043,5356,7055三种焊接材料对喷射成形7475铝合金TIG焊接头的热裂纹敏感性进行了研究,对接头的力学性能进行了测试,分析了接头的微观组织及裂纹的形貌、相组成.结果表明,采用5356焊丝时热输入对焊接热裂纹敏感性影响较大,高热输入时母材中的铜和锌向焊缝进行扩散和焊缝中的镁在熔合区形成α-Al,Al0.403Zn0.597和Al7 Cu3 Mg6相的低熔共晶组织,并在晶界和枝晶间形成偏析,在焊接应力的作用下在熔合区内产生了贯穿性热裂纹;低热输入时接头没有出现热裂纹,但强度只有184 MPa;而4043和7055两种焊丝的热裂纹敏感性较小.

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,Al0.403Zn0.597 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.