CN112475540B

CN112475540B - Welding method for inhibiting cracks of aluminum alloy T-shaped joint

Info

Publication number: CN112475540B
Application number: CN202011268269.XA
Authority: CN
Inventors: 雷正龙; 黎炳蔚; 夏佩云; 胡蓝; 尹玉环; 张新瑞; 陈彦宾
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2020-11-13
Filing date: 2020-11-13
Publication date: 2022-07-05
Anticipated expiration: 2040-11-13
Also published as: CN112475540A

Abstract

A welding method for inhibiting cracks of an aluminum alloy T-shaped joint relates to the field of welding. The invention aims to solve the problem of hot cracks existing in double-side laser welding of the aluminum alloy T-shaped joint. The invention mainly utilizes the components of the welding wire 1 to enhance the internal consistency of the welding seam and improve the welding seam strength, and utilizes the components of the welding wire 2 to inhibit cracks at the solidification front of a rear molten pool. The invention can further eliminate air holes and reduce heat input by adopting heat sources such as swinging laser, pulse/alternating current CMT and the like on the premise of ensuring the integral flowing trend of the molten pool. The invention is applied to the field of welding in the manufacturing industry.

Description

Welding method for inhibiting cracks of aluminum alloy T-shaped joint

Technical Field

The invention belongs to the field of material processing engineering, and particularly relates to a welding method for inhibiting cracks of an aluminum alloy T-shaped joint.

Background

In the manufacturing industry of airplanes, automobiles, rolling stock and the like, in order to reduce the self weight of a carrying tool and improve the carrying capacity, light metal alloys and thin-walled lightweight structures are increasingly adopted. Light alloys mainly made of titanium alloys and aluminum alloys are widely applied to structural member manufacturing in the fields of aerospace and the like, so as to meet the development requirements of modern aircrafts on light weight and high performance of key structural members. In the manufacturing process of the aerospace light alloy thin-wall structural part, the connection between a wall plate and a stringer is usually involved, and the weight reduction effect is obvious after the traditional riveting process is replaced by welding. In recent years, with the rapid development of lasers, laser welding is widely applied to the connection of aluminum alloy structural members. The connection of the aluminum-lithium alloy skin-stringer structural part of the aerospace craft is realized by adopting a double-laser-beam double-side synchronous welding technology, which is a problem to be solved urgently at present. However, due to the characteristics of the aluminum alloy and the characteristics of the T-shaped joint structure, the problems that welding seams, air holes, cracks, deformation and the like are difficult to solve by means of independent welding methods in both traditional welding and advanced laser welding are solved. The stringer and the skin are formed by rolling the aluminum alloy, and the aluminum alloy has the characteristics of larger solidification temperature range, linear expansion coefficient and sharp cooling and sharp heating during laser welding, so that the defect of welding hot cracks is easily caused during the laser welding, and the bearing and mechanical properties of a welding line are greatly reduced.

In order to reasonably regulate and control the weld joint structure in the process of bilateral laser synchronous welding so as to inhibit defects such as heat cracks, and the like, welding rolling, stress presetting, repair after welding and the like are generally adopted, for example, patent CN201610378627.X provides a device and a method for inhibiting welding heat cracks of a T-shaped structural member, and stress fields generated when the T-shaped structural member is welded with a stringer are reduced by pretensioning a skin, so that the possibility of weld joint cracking is reduced. Patent CN201610633577.5 proposes a dual laser beam welding method for reducing welding thermal cracks of T-shaped joints, which performs synchronous rolling on both sides of the molten pool to release the welding stress field and reduce the thermal cracks of the weld joint. However, the methods for eliminating the stress field are limited by the size, the form and the distribution of the structural member, the purlin form and the distribution, the application universality is poor, and the suppression of cracks cannot be ensured only from the perspective of reducing the stress field due to the continuous change of the strength of the stress field. And the modes of post-welding repair and the like easily cause repeated softening of joints, seriously reduce the performance and possibly generate new hot crack defects, so that the components of the welding seam per se need to be regulated and controlled to reduce the cracking tendency of the welding seam.

Disclosure of Invention

The invention aims to provide a welding method for inhibiting cracks of an aluminum alloy T-shaped joint, aiming at solving the problem of hot cracks existing in double-side laser welding of the aluminum alloy T-shaped joint.

The invention relates to a welding method for inhibiting cracks of an aluminum alloy T-shaped joint, which is carried out according to the following steps:

firstly, machining a part to be welded of a workpiece into required precision according to requirements, and polishing or cleaning the surfaces of two sides of the machined workpiece;

fixing the polished or cleaned workpiece to be welded on a welding tool fixture, wherein a stringer is vertical to the surface of a skin, welding is carried out in a mode of combining double-sided laser wire filling and CMT, the upper pretightening force is not less than 50N, the inclination angle alpha of a welding wire 1 is 15-35 degrees, the laser inclination angle beta is 5-10 degrees, the inclination angle gamma of a welding gun is 30-50 degrees, and the inclination angle theta of a composite welding head is 15-40 degrees; a welding wire 2 is arranged on the welding gun;

adopting the same parameters for the lasers on the two sides, wherein the defocusing amount of the lasers is minus 5-plus 5mm, the laser power is 1000-7000W, the welding speed is 4-12 m/min, the wire feeding speed is 100-750 mm/min, the optical fiber spacing is 3-8mm, the arc current is 50-140A, the arc voltage is 8-30V, the protective gas adopts Ar gas or Ar/He mixed gas, and the flow is 20-60L/min;

in the actual welding process, a robot integrated system is adopted to control welding technological parameters, firstly, a laser is controlled to emit laser, then, an electric arc is started, a wire feeder feeds welding wires, and finally, a robot is controlled to enable a composite welding head to move synchronously to complete the welding process;

wherein the welding wire 1 comprises the components of 0.9 to 1.1 percent of Li, 3.5 to 4.5 percent of Cu, 0.32 to 0.44 percent of Mg, 0.3 to 0.4 percent of Ag, less than 0.1 percent of Fe, 0.1 to 2 percent of Si, 0.4 to 1.2 percent of Er, 0.43 to 0.85 percent of Zr and the balance of Al;

the welding wire 2 is used for a CMT arc welding gun and comprises 12-15% of Si, less than 0.2% of Fe, 0.02-0.04% of Mn, less than 0.1% of Zn, 0.01-0.03% of Mg, 0.2-0.8% of Sc and the balance of Al.

Further, the upper pretightening force in the step two is not less than 50N, the inclination angle alpha of the welding wire 1 is 20-30 degrees, the laser inclination angle beta is 5-8 degrees, the inclination angle gamma of the welding gun is 35-40 degrees, and the inclination angle theta of the composite welding head is 20-40 degrees.

Further, the upper pretightening force in the step two is not less than 50N, the inclination angle alpha of the welding wire 1 is 15-30 degrees, the laser inclination angle beta is 5-8 degrees, the inclination angle gamma of the welding gun is 35-45 degrees, and the inclination angle theta of the composite welding head is 25-40 degrees.

Furthermore, the defocusing amount of the laser in the third step is minus 3 to plus 3mm, the power of the laser is 2000 to 5000W, the welding speed is 6 to 10m/min, the wire feeding speed is 200 to 500mm/min, the distance between optical fibers is 4 to 6mm, the arc current is 50 to 100A, the arc voltage is 10 to 20V, the protective gas adopts Ar gas or Ar/He mixed gas, and the flow rate is 30 to 50L/min.

Furthermore, the defocusing amount of the laser in the third step is minus 3 to plus 3mm, the laser power is 3000 to 6000W, the welding speed is 5 to 8m/min, the wire feeding speed is 300 to 600mm/min, the optical fiber spacing is 5 to 7mm, the arc current is 70 to 90A, the arc voltage is 15 to 25V, the protective gas adopts Ar gas or Ar/He mixed gas, and the flow is 35 to 45L/min.

Furthermore, the defocusing amount of the laser in the third step is minus 1 to plus 1mm, the laser power is 3000 to 4000W, the welding speed is 7 to 8m/min, the wire feeding speed is 300 to 400mm/min, the optical filament spacing is 5 to 8mm, the arc current is 80 to 120A, the arc voltage is 15 to 25V, and the protective gas adopts Ar gas or Ar/He mixed gas, and the flow is 40 to 50L/min.

Furthermore, the welding wire 1 comprises 1.0 percent of Li, 3.8 to 4.2 percent of Cu, 0.36 to 0.42 percent of Mg, 0.4 percent of Ag, less than 0.1 percent of Fe, 0.1 to 0.2 percent of Si, 0.5 to 0.6 percent of Er, 0.46 to 0.5 percent of Zr and the balance of Al;

the welding wire 2 comprises 12-13% of Si, less than 0.2% of Fe, 0.03-0.04% of Mn, less than 0.1% of Zn, 0.02-0.03% of Mg, 0.4-0.6% of Sc and the balance of Al.

Further, the laser is CO₂A gas laser, a YAG solid laser, or a semiconductor laser.

The invention adopts a double-side laser wire filling-CMT composite welding mode, as shown in figure 1, a welding wire 1, a laser beam and a CMT welding gun (welding wire 2) are arranged in sequence from front to back. Wherein the welding wire 1 comprises 0.9-1.1% of Li, 3.5-4.5% of Cu, 0.32-0.44% of Mg, 0.3-0.4% of Ag, less than 0.1% of Fe, 0.1-2% of Si, 0.4-1.2% of Er, 0.43-0.85% of Zr and the balance of Al. The welding wire 2 comprises 12-15% of Si, less than 0.2% of Fe, 0.02-0.04% of Mn, less than 0.1% of Zn, 0.01-0.03% of Mg, 0.2-0.8% of Sc and the balance of Al. Er, Zr and other elements in the welding wire 1 can refine grains, and the density of the Er, Zr and other elements is slightly larger than that of aluminum, so that the Er, Zr and other elements easily flow into the bottom of a molten pool along with the molten pool, the component difference between the bottom of the molten pool (the central position of a T-shaped joint) and two sides is reduced, and cracks are prevented from being generated and expanded from the center of a welding line due to the component difference. The Er and Zr composite addition generates Al3(Er, Zr) nucleation particles, compared with the Al3Zr and Al3Er, the mutual promotion effect of Er and Zr generates better effect when a smaller amount of rare earth alloy elements are added, the equiaxed crystal formation is promoted, and the hot cracking is inhibited. The Si element in the welding wire 2 can inhibit the generation of aluminum alloy welding cracks and repair a crack source, but the welding seam strength is reduced due to the excessively high content of the Si element, so that the welding wire is used for welding an external supplement layer, the Sc element has the density close to that of a base metal and can be used as an external layer strengthening element, and the problems of performance deterioration, large crystal grains and the like caused by the excessively high content of the Si element are solved. In the invention, the distance between the laser and the arc (light filament distance) is kept between 3mm and 8mm, and the functions of the invention comprise: 1. the shape of the molten pool is prolonged, the cooling speed is reduced, the residual stress intensity is reduced, and the cracking tendency is reduced. 2. The phenomenon that the welding wire 2 and the welding wire 1 are mixed in large quantity due to the fact that the distance between laser and an arc is too close (the distance between a CMT arc and the laser in conventional welding is generally within 3 mm) is avoided, and the internal strength of a welding seam is remarkably reduced.

The invention mainly utilizes the components of the welding wire 1 to enhance the internal consistency of the welding seam and improve the welding seam strength, and utilizes the components of the welding wire 2 to inhibit cracks at the solidification front of a rear molten pool. The hot crack in the welding seam is generally caused by the liquid film formed by eutectic substances with low melting point and the welding residual stress field, and the welding wire 2 inhibits the cracking caused by insufficient liquid film supplement in the final stage of solidification by increasing the cost ratio of the low melting point and adding other crack inhibiting elements, thereby inhibiting the micro-crack, the transverse and longitudinal through crack of the whole welding seam and the like. But at the same time to control the limited mixing of the components of the welding wire 2 and the welding wire 1, the welding wire 2 component being mainly located at the rear solidification front in the welding direction. In the depth direction, the components of the welding wire 2 are mainly distributed on the upper layer of the molten pool, and a small amount of the welding wire permeates into the laser action area on the lower half part of the molten pool, so that the purposes of inhibiting cracks and not damaging the strength are achieved. Meanwhile, the filling layer of the welding wire 2 exceeds the height of the extra height of a generally required welding seam, so that on one hand, the sectional area is increased, the overall load capacity of the joint is improved, and on the other hand, part of the welding wire can be removed when needed, and the purposes of reducing weight and releasing a stress field are achieved.

Compared with other double-side welding modes, the invention has the following advantages:

1. the welding wire has the advantages that the welding wire is specially designed, the difference between the center and the edge of the welding seam in the laser area is small, the effects of grain refinement, crack inhibition, strength improvement and the like are achieved under the action of Er and Zr elements, the crack initiation is inhibited by adopting high-content Si elements in the arc area, and crack defects, particularly through cracks and the like are prevented.

2. Compared with methods such as preset stress or deformation, the method improves the components of the welding seam, reduces the forming tendency of cracks, is more suitable for various production conditions, and can also be combined with the methods such as the preset stress for welding. In addition, the invention can adopt heat sources such as swinging laser, pulse/alternating current CMT and the like to further eliminate air holes, reduce heat input and the like on the premise of ensuring the whole flowing trend of the molten pool.

3. The arc filling layer has excellent crack-stopping effect, can inhibit crack propagation besides inhibiting cracks during solidification, reduces the possibility of quick brittle failure of the joint and avoids accidents. Meanwhile, the thickness of the filling layer can be increased during welding, polishing and trimming are carried out after welding, internal stress is released in time, and cracking is avoided.

4. Due to the adoption of a smaller CMT welding specification, the joint softening effect caused by the CMT welding specification is far smaller than the performance enhancement caused by the change of the joint size, and the problems of repeated softening of the joint and a heat affected zone and the like caused by repeated melting are avoided.

Drawings

FIG. 1 is a schematic diagram of a double-sided laser wire-filling-CMT hybrid welding;

FIG. 2 is a cross-sectional view of a weld joint of a 2195 aluminum-lithium alloy 4mm stringer and a 6mm skin T-joint welded by double-sided laser filler wire welding at a comparative example;

FIG. 3 is a graph of the joint topography obtained for comparative example dual-sided laser filler wire welding;

FIG. 4 is a cross-sectional view of a weld joint of a 2195 aluminum-lithium alloy 4mm stringer and a 6mm skin T-joint welded by double-sided laser wire-filling-CMT hybrid welding in example 1;

FIG. 5 is a graph of the joint topography obtained by the double-sided laser wire-filling-CMT hybrid welding of example 1.

FIG. 6 is a cross-sectional view of a weld joint of a 2195 Al-Li alloy 4mm stringer and a 6mm skin T-joint welded by double-sided laser wire-filling-CMT hybrid welding in example 2;

FIG. 7 is a graph of the joint topography obtained by the double-sided laser wire-filling-CMT hybrid welding of example 2.

Detailed Description

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.

To make the objects, aspects and advantages of the embodiments of the present invention more apparent, the following detailed description clearly illustrates the spirit of the disclosure, and any person skilled in the art, after understanding the embodiments of the disclosure, may make changes and modifications to the technology taught by the disclosure without departing from the spirit and scope of the disclosure.

The exemplary embodiments of the present invention and the description thereof are provided to explain the present invention and not to limit the present invention.

Respectively welding a 2195 aluminum-lithium alloy 4mm stringer and a 6mm skin T-shaped joint by using conventional double-side laser filler wire welding and the method. The specific experimental method is as follows:

example 1

The method for welding the 2195 aluminum lithium alloy 4mm stringer and the 6mm skin T-shaped joint comprises the following steps:

processing a part to be welded of a workpiece into required precision according to requirements, and polishing or cleaning the surfaces of two sides of the processed workpiece;

fixing the polished or cleaned workpiece to be welded on a welding tool fixture, wherein the truss strips are perpendicular to the surface of the skin, the upper pretightening force is not less than 50N, the inclination angle alpha of the welding wire 1 is 20 degrees, the laser inclination angle beta is 52 degrees, the inclination angle gamma of the welding gun is 35 degrees, and the inclination angle theta of the composite welding head is 32 degrees.

Adopting the same parameters on two sides, wherein the defocusing amount of laser is +/-3 mm, the power of the laser is 5000W, the welding speed is 5m/min, the wire feeding speed is 180mm/min, the distance between optical fibers is 5mm, the electric arc current is 85A, the electric arc voltage is 17V, the protective gas adopts Ar gas, and the flow is 25L/min;

in the actual welding process, the robot integrated system is adopted to control the welding technological parameters, firstly the laser is controlled to emit laser, then the arc is started, the welding wire is fed by the wire feeder, and finally the robot is controlled to enable the composite welding head to synchronously move to complete the welding process.

The welding wire 1 comprises 1.0 percent of Li, 3.5 percent of Cu, 0.37 percent of Mg, 0.35 percent of Ag, less than 0.1 percent of Fe, 0.8 percent of Si, 0.7 percent of Er, 0.6 percent of Zr and the balance of Al. The welding wire 2 comprises 13 percent of Si, less than 0.2 percent of Fe, 0.03 percent of Mn, less than 0.1 percent of Zn, 0.01 percent of Mg, 0.5 percent of Sc and the balance of Al.

Example 2

fixing the polished or cleaned workpiece to be welded on a welding tool fixture, enabling the row bar to be perpendicular to the surface of the skin, enabling the upper pretightening force to be not less than 50N, enabling the inclination angle alpha of the welding wire 1 to be 20 degrees, enabling the laser inclination angle beta to be 52 degrees, enabling the welding gun inclination angle gamma to be 35 degrees and enabling the inclination angle theta of the composite welding head to be 32 degrees.

Adopting the same parameters on two sides, wherein the defocusing amount of laser is +/-3 mm, the power of the laser is 5000W, the welding speed is 5m/min, the wire feeding speed is 180mm/min, the distance between optical fibers is 2mm, the electric arc current is 85A, the electric arc voltage is 17V, the protective gas adopts Ar gas, and the flow rate is 25L/min;

and fourthly, in the actual welding process, controlling welding technological parameters by adopting a robot integrated system, controlling a laser to emit laser, then carrying out arc striking and feeding welding wires by a wire feeder, and finally controlling the robot to enable the composite welding head to synchronously move to complete the welding process.

Comparative example

The conventional double-side laser filler wire welding process for welding the 2195 aluminum lithium alloy 4mm stringer and the 6mm skin T-shaped joint of the embodiment is as follows:

fixing the polished or cleaned workpiece to be welded on a welding fixture, wherein the truss strips are vertical to the surface of the skin, the upper pretightening force is not less than 50N, the inclination angle alpha of a welding wire (the mark is ER4047) is 20 degrees, the laser inclination angle beta is 52 degrees, and the inclination angle theta of a welding head is 32 degrees.

Adopting the same parameters on both sides, wherein the defocusing amount of the laser is +/-3 mm, the power of the laser is 5500W, the welding speed is 5m/min, the wire feeding speed is 230mm/min, the protective gas adopts Ar gas, and the flow rate is 25L/min;

As a result, as shown in fig. 2 to 7, fig. 2 and 3 are photographs of the cross-section and surface of a weld bead of a conventional double-sided laser filler wire welding 2195 aluminum lithium alloy 4mm stringer and 6mm skin T-joint, and it can be seen that a through crack exists in the center of the weld bead except for a small amount of blowholes and progresses in the welding direction, and weld cracks distributed in the welding direction are seen on the surface of the weld bead and located in the center of the weld bead. Resulting in direct post weld cracking.

Fig. 4 and 5 are photographs of the cross section and the surface of the weld joint formed by welding the 2195 aluminum-lithium alloy 4mm stringer and the 6mm skin T-shaped joint in the embodiment 1, and it can be seen that the volume of the weld joint is relatively large, the filling amount is increased, and the hot crack defect in the weld joint is well inhibited. The surface appearance of the welding seam is full, the width of the welding seam is increased compared with the width of the welding seam by the conventional method, and no obvious surface crack is seen.

Fig. 6 and 7 are photographs of the cross section and the surface of a weld joint formed by welding a 2195 aluminum-lithium alloy 4mm stringer and a 6mm skin T-shaped joint in the embodiment 2, wherein the formed side of the weld joint is close to that in the embodiment 1, no crack defect exists, but a pore defect is generated in the weld joint after a small light wire distance is applied, and the pressure of an electric arc on a laser molten pool area is large when the light wire distance is small, so that the two sides are formed with large difference. The parameter is only applicable to the flat butt joint and is not applicable to bilateral symmetric synchronous welding. And the welding performance is reduced due to excessive mixing of the welding wire components, which is only 73.6% of that of example 1.

It is thus understood that the method of the present invention can significantly suppress surface cracking and increase the width volume of the weld. But the process window is small, and the relative butt joint is changed, so that the butt joint optimal parameters cannot be directly used.

Claims

1. A welding method for inhibiting cracks of an aluminum alloy T-shaped joint is characterized by comprising the following steps:

fixing the polished or cleaned workpiece to be welded on a welding tool fixture, wherein a stringer is vertical to the surface of a skin, welding is carried out in a mode of combining double-sided laser wire filling and CMT, the upper pretightening force is not less than 50N, the inclination angle alpha of a welding wire 1 is 15-35 degrees, the laser inclination angle beta is 5-10 degrees, the inclination angle gamma of a CMT arc welding gun is 30-50 degrees, and the inclination angle theta of a composite welding head is 15-40 degrees; a welding wire 2 is arranged on the CMT arc welding gun;

adopting the same parameters for bilateral laser, wherein the defocusing amount of the laser is minus 5-plus 5mm, the laser power is 1000-7000W, the welding speed is 4-12 m/min, the wire feeding speed is 100-750 mm/min, the optical fiber spacing is 3-8mm, the arc current is 50-140A, the arc voltage is 8-30V, the protective gas adopts Ar gas or Ar/He mixed gas, and the flow is 20-60L/min;

2. The welding method for inhibiting the cracks of the T-shaped joint of the aluminum alloy according to claim 1, wherein the upper pretightening force in the second step is not less than 50N, the inclination angle alpha of the welding wire 1 is 20-30 degrees, the laser inclination angle beta is 5-8 degrees, the inclination angle gamma of the CMT arc welding gun is 35-40 degrees, and the inclination angle theta of the composite welding joint is 20-40 degrees.

3. The welding method for inhibiting the cracks of the aluminum alloy T-shaped joint according to claim 1, wherein the upper pretightening force in the second step is not less than 50N, the inclination angle alpha of the welding wire 1 is 15-30 degrees, the laser inclination angle beta is 5-8 degrees, the inclination angle gamma of the CMT arc welding gun is 35-45 degrees, and the inclination angle theta of the composite welding joint is 25-40 degrees.

4. The welding method for inhibiting the cracks of the T-shaped joint of the aluminum alloy according to claim 1, characterized in that the defocusing amount of the laser in the third step is-3 to + 3mm, the laser power is 2000 to 5000W, the welding speed is 6 to 10m/min, the wire feeding speed is 200 to 500mm/min, the distance between the optical wires is 4 to 6mm, the arc current is 50 to 100A, the arc voltage is 10 to 20V, the protective gas adopts Ar gas or Ar/He mixed gas, and the flow rate is 30 to 50L/min.

5. The welding method for inhibiting the cracks of the T-shaped joint of the aluminum alloy according to claim 1, wherein the defocusing amount of the laser is-3 to-3 mm, the laser power is 3000 to 6000W, the welding speed is 5 to 8m/min, the wire feeding speed is 300 to 600mm/min, the distance between optical wires is 5 to 7mm, the arc current is 70 to 90A, the arc voltage is 15 to 25V, the protective gas is Ar gas or Ar/He mixed gas, and the flow is 35 to 45L/min.

6. The welding method for inhibiting the cracks of the T-shaped joint of the aluminum alloy according to claim 1, characterized in that in the third step, the defocusing amount of the laser is minus 1 to plus 1mm, the laser power is 3000 to 4000W, the welding speed is 7 to 8m/min, the wire feeding speed is 300 to 400mm/min, the distance between optical wires is 5 to 8mm, the arc current is 80 to 120A, the arc voltage is 15 to 25V, the protective gas adopts Ar gas or Ar/He mixed gas, and the flow rate is 40 to 50L/min.

7. The welding method for inhibiting the cracks of the T-shaped joint of the aluminum alloy according to claim 1, wherein the welding wire 1 comprises 1.0 percent of Li, 3.8 to 4.2 percent of Cu, 0.36 to 0.42 percent of Mg, 0.4 percent of Ag, less than 0.1 percent of Fe, 0.1 to 0.2 percent of Si, 0.5 to 0.6 percent of Er, 0.46 to 0.5 percent of Zr and the balance of Al;

8. The welding method for inhibiting the cracks of the T-shaped joint of the aluminum alloy according to claim 1, wherein a laser is CO₂A gas laser, a YAG solid laser, or a semiconductor laser.