CN103572180A - Novel reinforcement technique of 6XXX aluminum alloy welding joint - Google Patents

Abstract

The invention discloses a novel reinforcement technique of a 6XXX aluminum alloy welding joint, mainly solves the defects such as high cost, large equipment and noise, complex operation, workpiece damage, additional consumption of materials and energy, additional increment of workpiece weight and residual stress, reduction of workpiece plasticity and air hole mingling in the traditional reinforcement methods of the 6XXX aluminum alloy welding joint, and achieves the reinforcement effect to the 6XXX aluminum alloy welding joint. The technique comprises the specific operation steps of solution treatment, subzero treatment and ageing treatment. The technique has the advantages of simple technique, low cost, ideal reinforcement effect, energy conservation, environmental protection and largely improved strength and plasticity, can effectively solve the problems of air holes and mingling inside the joint, and has excellent industrial application prospect.

Description

A kind of strengthening novel process of 6XXX welded joints in aluminium alloy

Technical field

The present invention relates to welding, thermal treatment and the deep cooling intensive treatment technical field of aluminium alloy, a kind of strengthening novel process of 6XXX welded joints in aluminium alloy is provided especially.

Background technology

The excellent over-all propertieies such as 6XXX aluminium alloy is good with its excellent processing characteristics, high strength, plasticity, anti-corrosion antifatigue, are widely used in the industrial circles such as Aeronautics and Astronautics, automobile, machinofacture, boats and ships and chemistry.In these sector applications, usually can run into and need to weld aluminum alloy spare part; and due to the singularity of aluminium alloy itself; make it when welding, need higher heat input; make easily to cause that the problems such as recovery and recrystallization and grain coarsening occur welding zone tissue in welding process; make welding joint produce softening, mechanical property decline; cause its service ability greatly to reduce, often aluminum apparatus or component failure or destruction cause because welding joint position destroys.Particularly particularly serious as the softening problem of welding joint of 6XXX heat-treatable strengthened aluminum alloy, its reason is mainly that second-phase (strengthening phase) precipitation under welding Effect of Hyperthermic Environment due to heat affected zone is separated out and gathers and grow up, strengthening effect is disappeared, form " overaging " softening, welding joint weld metal zone is as-cast structure simultaneously, easily produce some welding flaws, pore for example, be mingled with etc., these defects will cause strength of welded joint to reduce, and then affect member use properties, 6XXX welded joints in aluminium alloy is softening and defect is very general, have a strong impact on the work-ing life of workpiece, even may cause great casualty accident.

At present, both at home and abroad the method for 6XXX welded joints in aluminium alloy strengthening is mainly contained the methods such as synchronous rolling or hammering, soldering tip reinforcing, postweld heat treatment, these methods are reinforcing joint to a certain extent all, but all has some problems, specific as follows: 1. synchronous rolling or hammering.The method be in welding process butt welded seam and adjacent area thereof implement to roll or hammering to improve tensile strength and the fatigue strength of welding joint, but the method required equipment is huge, can not facilitate mobile operating, field construction difficulty, noise is large, once investment and current consumption are large, are unfavorable for energy-conservationly, and the method efficiency is low, poor controllability, effect is unstable, and required labour intensity is large, causes the problems such as damage of workpiece simultaneously.2. soldering tip method for strengthening.By increasing welding joint thickness, reach the method that improves supporting capacity, the method has increased the extra consumption of starting material and the energy, increased the overall weight of workpiece simultaneously, also can produce unrelieved stress in joint thickening place, cause and come off, insecure, cause huge potential safety hazard, often only for large-scale component.3. postweld heat treatment, the method can improve the intensity of welding joint to a certain extent, but is also accompanied by declining to a great extent of plasticity simultaneously, for plasticity, requires high workpiece inapplicable.In addition, the method is processed whole process all needs Welded Joints to carry out heating operation, in whole process heating, can cause the inner original gas hole defect of welding joint to be heated swells, finally be retained in inside workpiece, make workpiece local stress concentration and the stress corrosion problem of producing in process under arms, affect the use properties of workpiece, the method cannot solve plasticity, pore and Inclusion Problem.

In a word, above-mentioned several prior aries can play certain strengthening effect to 6XXX welded joints in aluminium alloy, but all exist the limitation of some technical disadvantages and application.

Summary of the invention

The object of the invention is to the enhancement method for above-mentioned industrial 6XXX welded joints in aluminium alloy, overcome the deficiency of prior art, provide a kind of and have that processing method is simple, running cost is low, noiseless, pollution-free, do not damage workpiece, effectively solve the 6XXX welded joints in aluminium alloy strengthening novel process of the advantages such as pore Inclusion Problem, strengthening effect be remarkable.

The present invention is achieved like this: 1. by 6XXX welded joints in aluminium alloy 430 ℃ ~ 580 ℃ solid solutions 1 hour ~ 3 hours; 2. the welding joint after solid solution is proceeded to rapidly in 15 ℃ ~ 25 ℃ cold water and be cooled to room temperature, be no more than 60s transfer time; 3. the cooled welding joint of cold water is put into cryogenic treatment apparatus, with the speed of (4 ℃ ~ 11 ℃)/min, be cooled to-130 ℃ ~-196 ℃; 4. be incubated 4 hours ~ 24 hours; 5. take out welding joint and put into heating and heat-insulating device, with the speed of (4 ℃ ~ 11 ℃)/min, be heated to 100 ℃ ~ 190 ℃; 6. be incubated 6 hours ~ 24 hours; 7. powered-down, makes welding joint be cooled to room temperature with device.

Positively effect of the present invention has: 1. effectively solve pore and Inclusion Problem.Because urgent contraction in metal deep cooling process forms internal compressive stress field, form microcosmic compressive plastic deformation, the bubble of inside, weld metal zone and being mingled with etc. is tied and is expressed into workpiece surface, and the inner microvoid in welding zone reduces, and the compactness extent of matrix improves; 2. strengthening effect is remarkable.After the solution hardening of 6XXX welded joints in aluminium alloy, have Mg and Si atom segregation to a certain degree, along with the carrying out the decomposition of Mg enrichment group of timeliness, Mg-Si enrichment group grows up into GP district.In deep cooling process, retained substantially the super saturated solid solution body tissue after solution treatment, and sub-zero treatment suppresses Mg and Si atom segregation, make aluminium alloy produce larger condensate depression simultaneously, coordinate again heating and thermal insulation treating processes thereafter, the nucleation rate of strengthening phase increases, separate out more fully, precipitate is more even, fine and closely woven simultaneously, increases the pinning effect to dislocation.Thereby can additionally not increase on the basis of whole workpiece weight by solid solution-deep cooling-aging technique, substantially refinement welding joint region crystal grain and impel weld precipitated phase to dissolve after be more uniformly distributed in matrix, the comprehensive mechanical property of Welded Joints improves significantly.

The comprehensive mechanical properties such as 6XXX welded joints in aluminium alloy weld seam, heat affected zone and proximity structure refinement intensity plasticity thereof after the inventive method is processed are all improved: hardness can promote 7% ~ 15%, tensile strength can promote 8% ~ 17%, yield strength can promote 10% ~ 19%, and unit elongation can promote 6% ~ 13%, internal porosity and Inclusion Problem basically eliminate, fatigue resistance can promote 30% ~ 65%.

Advantage of the present invention is: 1. technique is simple.The inventive method technique is simple, and easy handling is suitable for industrialized popularization and use; 2. effectively solve pore and Inclusion Problem, the welding joint internal porosity after the inventive method is processed and be mingled with basically eliminate; 3. strengthening effect is desirable, and the comprehensive mechanical property of material is increased dramatically; 4. energy-conserving and environment-protective.Adopting liquid nitrogen is deep cooling source, does not corrode workpiece, and stable chemical performance, nontoxic, pollution-free, to environment zero harm; 5. low-cost.Liquid nitrogen is the byproduct of oxygen industry, and source is wide, cheap, has the features such as easy transportation and storage.

Embodiment

Below in conjunction with embodiment, the present invention is described in detail:

Embodiment 1

With 6061-T6 aluminium alloy, through argon arc welding, the welding joint after the welding of ER5356 welding wire is example, and operation steps is as follows: the solid solution 2 hours at 535 ℃ of 6061 welded joints in aluminium alloys of 1. crossing argon arc welding;

2. the welding joint after solid solution is proceeded to rapidly in 25 ℃ of cold water and is cooled to room temperature, be no more than 15s transfer time, put into cryogenic treatment apparatus after cooling;

3. the cooling rate with 3 ℃/min drops to-180 ℃ by the temperature in cryogenic treatment apparatus from room temperature;

4. be incubated 8 hours;

5. the welding joint taking out after sub-zero treatment is put into heating and heat-insulating device, is no more than 15s transfer time;

6. the heat-up rate with 7 ℃/min is raised to 160 ℃ by the temperature in heating and heat-insulating device from room temperature;

7. be incubated 6 hours;

8. powered-down, makes welding joint be cooled to room temperature with device.

Through above-mentioned steps, process front and back, the hardness of 6061-T6 aluminium alloy argon arc welding joint improves 12%, and tensile strength improves 14%, and yield strength improves 16%, and unit elongation improves 10%, and internal porosity is eliminated with being mingled with substantially, and fatigue resistance improves 52%.

Embodiment 2

The welding joint of 6082-T6 aluminium alloy after Laser Welding welding of take is example, and operation steps is as follows:

1. the solid solution 100 minutes at 545 ℃ of 6082 welded joints in aluminium alloys of crossing laser welding;

2. the welding joint after solid solution is proceeded to rapidly in 25 ℃ of cold water and is cooled to room temperature, be no more than 15s transfer time, put into cryogenic treatment apparatus after cooling;

3. the cooling rate with 5 ℃/min drops to-196 ℃ by the temperature in cryogenic treatment apparatus from room temperature;

4. be incubated 12 hours;

5. the welding joint taking out after sub-zero treatment is put into heating and heat-insulating device, is no more than 15s transfer time;

6. the heat-up rate with 6 ℃/min is raised to 180 ℃ by the temperature in heating and heat-insulating device from room temperature;

7. be incubated 6 hours;

8. powered-down, makes welding joint be cooled to room temperature with device.

Through above-mentioned steps, process front and back, the hardness of 6082-T6 Laser Welding of Aluminum Alloys joint improves 9%, and tensile strength improves 10%, and yield strength improves 12%, and unit elongation improves 8%, and internal porosity is eliminated with being mingled with substantially, and fatigue resistance has improved 37%.

Claims (2)

1. a strengthening novel process for 6XXX welded joints in aluminium alloy, comprises the steps:

(1) by 6XXX welded joints in aluminium alloy 430 ℃ ~ 580 ℃ solid solutions 1 hour ~ 3 hours;

(2) welding joint after solid solution is proceeded to rapidly in 15 ℃ ~ 25 ℃ cold water and be cooled to room temperature, be no more than 60s transfer time;

(3) the cooled welding joint of cold water is put into cryogenic treatment apparatus, with the speed of (4 ℃ ~ 11 ℃)/min, be cooled to-130 ℃ ~-196 ℃;

(4) be incubated 4 hours ~ 24 hours;

(5) take out welding joint and put into heating and heat-insulating device, with the speed of (4 ℃ ~ 11 ℃)/min, be heated to 100 ℃ ~ 190 ℃;

(6) be incubated 6 hours ~ 24 hours;

(7) powered-down, makes welding joint be cooled to room temperature with device.

2. according to the strengthening novel process of 6XXX welded joints in aluminium alloy claimed in claim 1, it is characterized in that: deep cooling used source is liquid nitrogen.