Resarch On Weldability Of 2519A Aluminum-copper Alloy

High-strength aluminum alloy 2519A-T87 is a kind of new structure material. This material has high specific strength highspecific stiffness, and good processability, it also has good stress corrosion resistance in severe environments such as sea, salt atmosphere. So it has great potential in the aeronautical and astronautical field. However there are no clear cut research results about the weldability of 2519A-T87 aluminum alloy and the structure of welding joint.In this paper, the argon-arc welding processibility and friction stir welding processibility of 2519A-T87 aluminum alloy, the welding joint mechanical property were researched by experiments. The decay resistances of the welding joint were analyzed.The experiments results indicated argon-arc welding processibility of 2519A-T87 aluminum alloy was good, which is better than 2A12 aluminum alloy, but was not as good as 5A06 aluminum alloy.The 2519A-T87 aluminum alloy had the tendency of welding heating crack. The welding material ought to select Al-Cu series,By warming up,the tendency of welding heating crack could be reduced.In order to reduce welding blow hole and crack,the welding material,the welding parameters were strictly controled.When aluminum alloy 2519A-T87/5A06-O were fusion welded, the gross Al2CuMg phase (S phase) round particles and unequilibrium eutectic formed by Mg2Si and matrix 1～10μm thick were come in to being between dendrites of solidification structures.Though welding nuclear area were formed by solidification structures,its hardness was higher than 5A06-O.The stretching stracture was in 5A06-O material.Aluminum alloy 2519A-T87/5A06-O welding nuclear area corrosion diffused mainly along dendrites. This corrosion diffuse way could be restrained by dendrites across arrange.The whole welding structure could obtain good decay resistance.When aluminum alloy 2519A-T87 was FSW (Friction Stir Welding), the gross Al2Cu phase and Fich-(Fe, Mn) phase iand Fich-(Fe, Mn) phase in the welding nuclear area were broken into pieces and distributed. During FSW, mechanical properties of welded joint were improved by the fine grain strengthening and second phase dispersion strengthening. At the heat reflection area, hardness value was the minimum, order of 78% of the base mental. After the post welding heat treatment, the welded joint mechanical properties weren't improved because of the complex base tissue and the second phase precipitation structural evolution.The break away corrosion resistant of 2519A-T87 aluminum alloy FSW welded joint was reduced. The corrosion resistant degree of base mental was EB and the degree of welded joint was EC+. After the post welding heat treatment, corrosion resistant degree of base mental and welded joint was reduced to ED.