CN-121972789-A - Welding method of dissimilar aluminum alloy

Abstract

The invention discloses a welding method of dissimilar aluminum alloy, which comprises the following steps of ① groove processing of a first aluminum alloy plate, second groove processing of a second aluminum alloy plate, wherein the inclination angles of the first groove and the second groove are different, ② assembling and positioning welding, namely, the first groove and the second groove are paired and reserved with root gaps d, reinforcing ribs are welded between the first aluminum alloy plate and the second aluminum alloy plate through positioning welding, ③ root welding, backing welding is carried out at the root to enable the root to be penetrated, ④ filling welding is carried out for multiple times by adopting 5R59 aluminum alloy welding wires containing Sc/Zr to form a welding joint, the first aluminum alloy plate and the second aluminum alloy plate form a welding structural member, and the interlayer temperature between adjacent welding beads in the welding process is less than or equal to 60 ℃. Compared with the prior art, the fatigue life of the welded structural part prepared by the method is longer.

Inventors

• MAO HUA
• LANG YUJING
• QIU MINGKUN
• LI JINBAO
• HAN FENG
• ZHANG ZEQUN
• LIU YANG
• JIN JIANGSHAN

Assignees

• 中国兵器科学研究院宁波分院

Dates

Publication Date

20260505

Application Date

20251209

Claims (10)

1. 1. A welding method of dissimilar aluminum alloy is characterized by comprising the following steps: ① The method comprises the steps of performing groove processing, namely processing a first aluminum alloy plate (1) to form a first groove (11), processing a second aluminum alloy plate (2) to form a second groove (21), wherein the inclination angles of the first groove (11) and the second groove (21) are different; ② Assembling and positioning welding, namely assembling the first groove (11) and the second groove (21) and reserving a root gap d, fixing the first groove and the second groove through positioning welding, and welding reinforcing ribs between the first aluminum alloy plate (1) and the second aluminum alloy plate (2); ③ Root welding, namely performing bottoming welding on the root to enable the root to be permeated; ④ And (3) carrying out multi-pass filling welding, namely carrying out multi-pass filling welding by adopting a 5R59 aluminum alloy welding wire containing Sc/Zr to form a welding joint, so that the first aluminum alloy plate (1) and the second aluminum alloy plate (2) form a welding structural member, and the interlayer temperature between adjacent welding beads in the welding process is less than or equal to 60 ℃.
2. 2. Welding method according to claim 1, characterized in that the first aluminium alloy sheet (1) and the second aluminium alloy sheet (2) are 7xxx series aluminium alloy sheets or 5xxx series aluminium alloy sheets.
3. 3. The welding method as recited in claim 2, wherein the 7xxx series aluminum alloy is a 7B52 aluminum alloy or a 7A52 aluminum alloy, and the 5xxx series aluminum alloy is A5R 60 aluminum alloy.
4. 4. The welding method according to claim 1, wherein the first groove (11) has an inclination angle of 70 ° -80 °, the second groove (21) has an inclination angle of 40 ° -50 °, the root of the second groove (21) has a blunt edge (22) of 6-8mm, and the root gap d of step ② is 2.5-3.5mm.
5. 5. The welding method according to claim 4, wherein an auxiliary groove (221) having an angle of 45 DEG to 60 DEG is provided inside the blunt edge (22).
6. 6. The welding method according to claim 1, wherein the 5R59 aluminum alloy welding wire comprises, by mass, 4.9-6.1% of Mg, 0.30-0.90% of Zn, 0.05-0.55% of Sc, 0.2-0.5% of Mn, 0.05-0.30% of Zr, and the balance of Al and unavoidable impurities.
7. 7. The welding method according to claim 1, wherein the welding voltage of the multi-pass filling welding in the step ④ is 18-25V, the welding current is 240-290A, the shielding gas is argon, the flow rate is 18-25L/min, and the purity is not less than 99.995%.
8. 8. The method of claim 1, wherein the multi-pass filler welding of step ④ comprises a first ground weld, a second filler weld, third through five cap welds, and a sixth back weld.
9. 9. The welding method according to claim 8, wherein the filler metal and the cover metal are welded together by two-pass secondary filler metal.
10. 10. The welding method according to any one of claims 1 to 9, wherein the weld zone of the welded joint obtained by the preparation method is of a uniformly refined equiaxed crystal structure, and the fatigue life is more than or equal to 10 7 times under the fatigue test condition that the stress ratio R=0.1 and the maximum load is 10 kN.

Description

Welding method of dissimilar aluminum alloy Technical Field The invention relates to the field of aluminum alloy, in particular to a welding method of dissimilar aluminum alloy. Background The aluminum alloy is widely applied to light-weight equipment structures of special vehicles, ships, aerospace and the like due to the characteristics of low density, high specific strength, good corrosion resistance and the like. In particular 7xxx series aluminium zinc magnesium series high strength aluminium alloys and 5xxx series aluminium magnesium series high toughness aluminium alloys, have an irreplaceable position in load bearing members and protective structures. However, in practical engineering, different series of aluminum alloys often need to be used in combination, for example, aluminum alloys such as 7a52, 7B52 and 5R60 bear different functions in the same structure, which makes the connection of dissimilar aluminum alloys a key link in the manufacturing of the structure. However, because of the significant differences in chemical composition, solidification characteristics, coefficient of thermal expansion, and weld thermal conductivity between 7xxx and 5xxx series aluminum alloys, a series of typical problems readily occur during fusion welding, including coarse weld solidification structure, high columnar grain fraction, strong weld hot crack sensitivity, significant softening of the semi-molten zone, insufficient bath wettability, and unstable root fusion. These problems are more pronounced in dissimilar metal welding, resulting in significant decreases in the strength, toughness and fatigue life of the welded joint, especially fatigue performance often failing to meet long-term service requirements for high reliability structures. The prior art provides various schemes for dissimilar aluminum alloy connection, such as conventional MIG/TIG fusion welding, friction stir welding and various auxiliary heat source welding processes, but has obvious limitations. The traditional fusion welding seam structure is easy to coarsen and hot cracks are difficult to avoid, the friction stir welding can improve the structure but is limited by plate thickness, equipment cost and welding configuration, and in addition, the common 5 xxx-series welding wire or 4 xxx-series welding wire is difficult to provide ideal structure refinement and joint fatigue performance in dissimilar aluminum alloy welding. Particularly under the welding condition of a thick plate with the thickness of 20-40mm, defects can be generated due to difficult penetration control and over high or insufficient heat input, and the fatigue life is seriously influenced. Therefore, improvements to existing dissimilar aluminum alloy joining methods are needed. Disclosure of Invention The technical problem to be solved by the invention is to provide a welding method of a dissimilar aluminum alloy for improving the fatigue life of a manufactured welding structural member aiming at the current state of the art. The technical scheme adopted for solving the technical problems is that the welding method of the dissimilar aluminum alloy is characterized by comprising the following steps: ① Groove processing, namely processing a first aluminum alloy plate 1 to form a first groove 11, and processing a second aluminum alloy plate 2 to form a second groove 21, wherein the inclination angles of the first groove 11 and the second groove 21 are different; ② Assembling and positioning welding, namely assembling the first groove 11 and the second groove 21, reserving a root gap d, fixing by positioning welding, and welding reinforcing ribs between the first aluminum alloy plate 1 and the second aluminum alloy plate 2; ③ Root welding, namely performing bottoming welding on the root to enable the root to be permeated; ④ And (3) carrying out multi-pass filling welding, namely carrying out multi-pass filling welding by adopting a 5R59 aluminum alloy welding wire containing Sc/Zr to form a welding joint, so that the first aluminum alloy plate 1 and the second aluminum alloy plate 2 form an integral piece, wherein the interlayer temperature between adjacent welding beads in the welding process is less than or equal to 60 ℃. The interlayer temperature is less than or equal to 60 ℃ to reduce the softening and hot cracking sensibility of a heat affected zone, a plurality of filling welds are formed on the outermost layer of the weld joint through a plurality of cover welds to form a weld bead with uniform width and thickness, and finally right-angle weld joint filling is carried out on the back surface area to strengthen the structural support of the root part and seal the non-penetration defect. Reinforcing ribs are provided to suppress welding deformation. Preferably, the first aluminum alloy sheet 1 and the second aluminum alloy sheet 2 are 7xxx series aluminum alloy sheets or 5xxx series aluminum alloy sheets. Preferably, the 7xxx series aluminum alloy is a 7B52 aluminum allo