CN-121972772-A - Preparation method of high-strength and high-toughness corrosion-resistant aluminum alloy welded joint

Abstract

The invention discloses a preparation method of a high-strength and high-toughness corrosion-resistant aluminum alloy welded joint, which belongs to the technical field of welding and heat treatment of aluminum alloy materials. The core logic is that the reliable connection of the alloy is realized through welding, partial welding defects are eliminated through solution treatment, the soluble second phase is dissolved, the aging time is accurately controlled, the uniform precipitation of eutectic silicon spheroidization and precipitation phases is promoted, and finally, the accurate matching relation of process-structure-performance is established.

Inventors

• DING HONGSHENG
• ZHANG RUNZE
• Lou Zhaokun
• TONG YUE
• TIAN JINCHANG
• DING YANGYANG
• SUN NAN

Assignees

• 哈尔滨工业大学

Dates

Publication Date

20260505

Application Date

20251222

Claims (3)

1. 1. A preparation method of a high-strength and high-toughness corrosion-resistant aluminum alloy welded joint is characterized by comprising the following steps: The method comprises the steps of preparing a base material and controlling components, namely selecting high-purity raw materials (pure magnesium, al is more than or equal to 99.996 wt percent, fe is less than or equal to 0.001 percent, al-Si intermediate alloy (Si is between 12 and 30 percent), al-Cu intermediate alloy (Cu is between 40 and 60 percent), fe is less than or equal to 0.45 percent, al-Ti intermediate alloy (Ti is between 3 and 8 percent)) to smelt in a 5-50 kW crucible resistance furnace, completely melting the raw materials at 700 to 760 ℃, adding Al-Cu intermediate alloy regulating components, refining and degassing by adopting high-purity argon or nitrogen, adjusting the temperature of a melt to 700 to 720 ℃, carrying out modification treatment, improving the appearance of eutectic silicon, introducing argon, refining again, standing, slagging off at 680 to 700 to 720 ℃, and casting to obtain an aluminum alloy plate, detecting components, and ensuring that the proportions of the target components (Si 6.5 to 7.5 percent, mg 0.4 to 0.8 percent, cu 0.4 to 0.8 percent, ti 0.08 to 0.02 percent and the balance of Al is 0.04 percent); Step two, welding Preparing before welding, namely processing an aluminum alloy plate into a double-sided groove with an included angle of 85-95 degrees, grinding the surface of the groove and the vicinity of a region to be welded with sand paper, removing greasy dirt and an oxide film until metallic luster is exposed, wiping the groove and the periphery within 50mm with acetone, and thoroughly removing impurities; fixing the paired plates on a welding table, reserving a gap of 3-5 mm, ensuring that the center of the gap coincides with the center line of a welding platform, and positioning by adopting a special fixture to prevent displacement in the welding process; The welding is implemented by adopting an alternating current tungsten electrode argon arc welding (TIG) welding machine, selecting a cerium tungsten electrode with the diameter of 4.0mm, wherein the components of the welding rod are consistent with those of a base metal; post-welding treatment, namely naturally cooling the plate to room temperature after welding, so as to avoid generating extra residual stress by rapid cooling; Step three, solution treatment Placing the welded plate subjected to air cooling into a heat treatment furnace, and heating to 540-550 ℃ at a heating rate of 5-15 ℃ per minute; step four, accurate artificial aging treatment And (3) placing the quenched welding plate into a heat treatment furnace, heating to 140-150 ℃ for pre-ageing for 2 hours, heating to 160-170 ℃ and preserving heat for 2-30 hours, wherein the temperature fluctuation in the heat preservation process is less than or equal to +/-5 ℃, the pressure is normal pressure, and naturally cooling to room temperature after ageing is finished.
2. 2. The method for preparing a high-strength and high-toughness corrosion-resistant aluminum alloy welded joint according to claim 1, wherein in the first step, an alterant used for modification treatment is one of Sr, sb, te or rare earth, and the mass ratio of the alloy to the alterant is 100:0.2-0.05.
3. 3. The method for preparing the high-strength and high-toughness corrosion-resistant aluminum alloy welded joint according to claim 1, wherein in the second step, welding current is 220-280A, arc voltage is 20-24V, welding speed is 8-12 cm/min, shielding gas is argon, and flow is 18-20L/min.

Description

Preparation method of high-strength and high-toughness corrosion-resistant aluminum alloy welded joint Technical Field The invention belongs to the technical field of welding and heat treatment of aluminum alloy materials, and particularly relates to a preparation method of a high-strength and high-toughness corrosion-resistant aluminum alloy welded joint, which is used for manufacturing and improving the performance of lightweight structural members in the fields of aerospace, automobiles, ships, national defense and the like. Background The related prior art is mainly focused on a welding process and a postweld performance regulation technology of Al-Si-Mg-Cu cast aluminum alloy, is mainly applied to manufacturing lightweight structural members in the fields of aerospace, automobiles, ships and national defense, and specifically comprises the following key technical directions and product characteristics: 1. The welding technology is that Tungsten inert gas (Tungsten INERT GAS WELDING, TIG) welding, laser welding, electron beam welding and other fusion welding methods are widely adopted to realize aluminum alloy connection, wherein TIG welding is the mainstream choice in industry due to moderate equipment cost and flexible operation. In the welding process, a single groove form is usually adopted, only basic oxide film cleaning and workpiece fixing are carried out before welding, and the weld joint forming is ensured by conventional adjustment of welding parameters (current, voltage, shielding gas flow and the like). 2. The main flow scheme of the heat treatment process is a combination process of solid solution treatment and single aging treatment or a direct aging process. The solution treatment temperature is mostly in the range of 530-550 ℃, the aging temperature is concentrated in 160-170 ℃, but the process parameters lack of accurate matching design aiming at the problems of softening of a heat affected zone of a welding joint, phase segregation and the like, and part of scenes are simplified processes, and the solution treatment is omitted and only single-temperature aging is carried out. 3. The performance optimization aims are that the core focuses on improving the strength and the hardness of the welding joint, and strengthening phase precipitation is promoted by adjusting heat treatment parameters so as to make up for performance degradation caused by welding heat circulation, and the defect of the cooperative optimization of corrosion resistance and mechanical properties is emphasized. The prior art/product has the following key defects, so that the performance and service reliability of the aluminum alloy welded joint are difficult to meet the high-end scene requirement: 1. The microstructure is not regulated sufficiently, defects are difficult to radically overcome, the existing heat treatment process is limited in improvement of the structural uniformity of the welded joint, the problems of second phase segregation, coarse grains and the like are easy to occur in a heat affected zone, the secondary dendrite spacing is obviously increased (up to 22 mu m), eutectic silicon is distributed in a lath shape or a block shape, the spheroidizing effect is poor, and the negative effects of harmful phases such as pi-Al 8Si6Mg3 Fe and the like cannot be effectively relieved. Meanwhile, the single solid solution or aging parameters are difficult to realize the sufficient dissolution and uniform precipitation of the strengthening phases such as Al 2Cu、Mg2 Si, and the size of the precipitated phases is uneven and the distribution is disordered. 2. The heat-affected zone softening is poor in balance, the tensile strength of the welding joint without heat treatment is only about 192MPa, the softening phenomenon of the heat-affected zone is obvious (the hardness is about 85 HV) even though the welding joint is subjected to conventional heat treatment, and the welding joint is difficult to effectively improve through the existing technology, so that the hardness difference of all areas of the joint is overlarge, and the whole bearing capacity is limited. In addition, the existing technology has the disadvantages of multi-side strength improvement, plastic and strength balance is often neglected, the elongation improvement effect is limited, and the brittle fracture risk of the joint is easily increased. 3. The corrosion resistance is optimized insufficiently, the service stability is poor, the influence of potential difference of a precipitated phase and a matrix on the corrosion behavior is not fully considered in the prior art, and a single heat treatment parameter easily causes overlarge local potential difference to form a large number of micro batteries so as to accelerate the corrosion process. The corrosion current density of the welding joint without heat treatment is as high as 9.03X10 -7 ACm -2, even though the conventional aging treatment is carried out, the corrosion resistance is obviously reduce