CN102357734A - Method for connecting 2XXX and 7XXX heterogeneous aluminum alloy by laser filler wire - Google Patents

Abstract

The invention discloses a method for connecting 2XXX and 7XXX heterogeneous aluminum alloy by the laser filler wire, which is suitable for the connection field of 2XXX and 7XXX-series of heterogeneous aluminum alloy. The method comprises the following steps of: firstly, assembling two aluminum alloy plates to be welded into a butt joint mode; regulating position relationship among a laser focal point, the wire falling point of an aluminum alloy welding wire and a butt joint gap between two aluminum alloy plates to ensure that the laser beam, the welding wire and the welded aluminum alloy plates are positioned on the reasonable opposite positions; and adopting reasonable welding parameters, laser power, welding speed, wire conveying speed and the like, utilizing AlCu or Alsi welding wires as filler material in the welding process to regulate the ingredient of the welding line and improve the performance of the joint. According to the method, the problems that the 2XXX and 7XXX heterogeneous aluminum alloy is difficult to connect, the welding line is softened during melting, and heat checking tendency exists can be solved.

Description

A kind of wire filling laser welding connects the method for 2XXX and 7XXX heterogeneity aluminum alloy in succession

Technical field:

The present invention is a kind of method for laser welding through filler wire connection 2XXX and 7XXX series heterogeneity aluminum alloy, is applicable to the connection area of 2XXX and 7XXX series heterogeneity aluminum alloy.

Technical background:

The manufacturing of transport facility will consider performance demands on the one hand, to consider on the other hand to make and use to the requirement of economy.For achieving the above object, need under the condition that guarantees vehicles performance, constantly alleviate own wt.But 2XXX and 7XXX aluminium alloy are two kinds of heat treatment high strength alumin ium alloys, are widely used in aerospace field with characteristics such as its low-density, high specific strengths, also are the substitution material of Modern High-Speed train, light-duty vehicle and car etc.Because the connectivity problem between the two inevitably appears in the extensive use of two kinds of aluminium alloys.The method of attachment of aerolite mainly is riveted joint traditionally, has increased the weight of structure like this.Mainly adopt being connected of 2XXX and 7XXX series heterogeneity aluminum alloy bonding, but bonding intensity is lower.Welding is the prefered method that addresses this problem.

Traditional welding method has great limitation for welding aluminum alloy.Arc welding method is because hot input quantity is bigger; Weld seam and heat affected area all serious ruckbildung can occur in two kinds of aluminum alloy welding termination process of 2XXX and 7XXX; Often think that the 2XXX series alloys uses traditional electrical arc-welding solderability not high, the then not recommended employing arc welding of 7XXX series alloys.Agitating friction is welded in the welding between 2XXX, 6XXX, 7XXX series alloys and the various aluminium alloy has all been obtained welding effect preferably, and stirring area is softened, upsetting force is big, the requirement that is installed is high, be difficult to carry out three-dimension flexible processing and speed of welding waits shortcoming slowly and limited its application aspect much but exist.Though the weldquality that electron-bombardment welding obtains increases substantially than arc welding intensity, reason such as high, consuming time and vacuum chamber space is limited owing to the electron-bombardment welding cost is difficult to be used widely.

Laser welding technology and traditional welding compared with techniques advantage are that the sweating heat input quantity is controlled, the heat affected area is little, speed of welding is fast, welding efficiency is high, welding deformation is little, the accessibility of light beam is good, are that other traditional heat sources can not be compared.Because the existence of dark molten aperture makes that the laser weld energy density is high, the heating cooling velocity is fast, can obtain narrower weld seam, make it become a kind of method of suitable aluminium alloy welding in the Laser Deep Penetration Welding process.And laser weld can be carried out complicated flexible 3 D processing, easily is automated, and has the wide range of commercial application prospect.In welding process, add the effect that filler wire not only plays stabilized welding process; Also between material to be welded, play good bridge linking effect; Help the connection between the dissimilar metal, and can effectively control the performance of the composition of welding point, the generation that suppresses fire check, raising welding point through the adjustment component of weld wire.These technical characterstics are that the connection between 2XXX and the 7XXX series heterogeneity aluminum alloy provides possibility.

In the Laser Deep Penetration Welding process; Laser power density surpasses the molten deeply threshold value of material and produces dark molten aperture; To help the absorption of material for laser light; Yet aperture is not a stable existence always, thereby it will produce wild effect and cause the welding process unstability under factor effects such as plasma, cause the deterioration of appearance of weld.During the laser weld aluminium alloy, because the evaporating pressure of Al is higher, so the unsettled phenomenon of aluminium alloy laser beam welding ubiquity.And since hydrogen in liquid aluminium alloy and solid aluminum alloy solubility than big-difference, easy formation hydrogen blistering in the aluminium alloy weld seam.Welding process instability and pore are the common problems of aluminium alloy welding.2XXX series alloy laser weld also need solve the softening problem of fire check and weld seam except that the characteristics with aluminium alloy welding; And the 7XXX series alloys will cause the instability of aperture, weld seam to soften owing to exist vapo(u)rability elements such as lower boiling Mg, Zn in the alloy during laser weld, and welding quality is descended.Thereby the connection of 2XXX and 7XXX series heterogeneity aluminum alloy has very big difficulty.

In laser beam welding, add filler wire and will reduce the temperature in Reciprocity of Laser & Materials district, the unstability of reduction welding process, can also adjust the composition of weld metal, improve hot cracking tendency, improve weld strength.The present invention will utilize the laser welding with filler wire method stabilized welding process; Problems such as hot tearing in solution 2XXX and the 7XXX high strength alumin ium alloy laser beam welding and pore; Again through regulating welding parameters such as chevilled silk spacing, wire feed rate, beam deviation amount; Further stabilized welding process, thus the wire filling laser welding of realizing 2XXX and 7XXX series heterogeneity aluminum alloy connects in succession.

Summary of the invention:

In order to solve the problem that exists in the welding of above-mentioned 2XXX and 7XXX heterogeneity aluminum alloy, the wire filling laser welding that the invention provides a kind of 2XXX of realization and 7XXX heterogeneity aluminum alloy connects method in succession.This method adopts the multikilowatt laser instrument as thermal source, in laser beam welding, adds welding wire for connecting metal, reduces the temperature in Reciprocity of Laser & Materials district on the one hand and comes stabilized welding process.On the other hand through regulating welding parameters such as chevilled silk spacing, wire feed rate, beam deviation amount, further stabilized welding process has not only realized the connection between two kinds of aluminium alloys, has solved hot tearing and pore problem, and weld strength has also reached higher level.

Technical scheme of the present invention is referring to Fig. 1-3; Laser fills silk and connects the method for 2XXX and 7XXX series heterogeneity aluminum alloy; It is characterized in that: at first material surface to be welded is cleaned; Then two kinds of aluminium alloy plates to be welded are assembled into the banjo fixing butt jointing among the figure, (having relatively high expectations to banjo fixing butt jointing during laser weld.Require end face to be welded straight, the slit between two end faces to be welded of banjo fixing butt jointing is less than 30% of laser spot place diameter.) wherein laser beam 3, wire feed nozzle 5 are fixed in the same plane with protection gas jets 4; Wire feed nozzle 5 lays respectively at the both sides of laser beam 3 with protecting gas jets 4; (laser beam 3 is incident angle 12 with the angle of vertical direction to laser beam 3 with incidence angle; Between 0-15 °) be incident to surface of steel plate; Angle (being wire feed angle 10) between aluminium alloy welding wire and mother metal 2,024 1 surfaces is between 45-60 °, and the angle (promptly protecting air horn degree 11) between protection gas jets and mother metal 7,075 2 surfaces is between 45-55 °; The fall spacing of silk point and laser spot of aluminium alloy welding wire is chevilled silk spacing 13, guarantee during welding that laser spot is put with the silk that falls of aluminium alloy welding wire and protective gas send into consistently, promptly the chevilled silk spacing is 0; Laser spot is laser side-play amount 14 (side-play amount is generally between 0.2-0.7mm) to the vertical range of butt joint aluminium alloy weld seam; In order to guarantee the stability of 2XXX and 7XXX series heterogeneity aluminum alloy welding process, the focus of laser beam is positioned on the 2XXX aluminium alloy plate 1.Except that guaranteeing above-mentioned parameter, in the process of welding, also need regulate laser power, speed of welding and wire feed rate and come accurately control sweating heat input quantity, realize being connected of 2XXX series and 7XXX series heterogeneity aluminum alloy.

In the laser beam welding, laser 3 acts on filler wire and the aluminium alloy plate to be welded (1 and 2) simultaneously, because the laser high energy density; Wire melting in the interaction region of laser and material; The aluminium alloy plate fusing also welding plasma 7, molten deeply aperture occur, a large amount of physics, chemical change has taken place, along with the motion of laser; New dark molten aperture constantly, stably form; The welding wire of fusing is constantly filled and is got into the molten bath, and the liquid bath temperature that leaves laser beam constantly reduces, and solidifies to form weld seam 6.So process constantly realizes the metallurgical binding between the material.

Welding process need guarantee aluminium alloy welding wire to send into direction opposite with welding direction 9, welding process adopts helium to do protective gas.Described heterogeneity aluminum alloy laser fills silk in the method for attachment, and LASER Light Source can be any one of CO2, Nd:YAG, semiconductor or optical-fiber laser, and the cross-sectional distribution of light beam need be a Gaussian distribution, and beam quality laser instrument preferably.

The welding wire of sending into the weld zone should be AlSi or AlCu welding wire, and diameter is between 0.8-1.2mm.

Two kinds of aluminium alloy plates to be welded are respectively 2XXX series and 7XXX series alloys.

Basic principle of the present invention is:

When welding, two kinds of aluminium alloy plates are assembled into the butt joint form; Concern through regulating the position that laser spot, aluminium alloy welding wire fall between the abutment joint of silk point and two kinds of aluminium alloy plates; Make laser beam, welding wire and welded the aluminium alloy plate three on rational relative position; Adopt rational welding parameter such as laser power, speed of welding and wire feed rate etc. again, make AlSi or the AlCu filler wire of fusing and aluminium alloy plate form transitional good connecting joint.

When wire filling laser welding connects 2XXX series and 7XXX series heterogeneity aluminum alloy in succession; At first material surface to be welded is cleaned; Be assembled into banjo fixing butt jointing, wherein laser beam 3, wire feed nozzle 5 are fixed in the same plane with protection gas jets 4, and wire feed nozzle 5 lays respectively at the both sides of laser beam 3 with protecting gas jets 4; Incidence angle 12 is between 0-15 °; Laser beam 3 is incident to material surface to be welded (1 and 2) with certain incidence angle 12, and wire feed angle 10 is between 45-60 °, and protection air horn degree 11 is between 45-55 °.Above-mentioned condition is the Wire-added primary condition that connects of laser.In order to guarantee the stability of laser weld 2XXX and 7XXX series heterogeneity aluminum alloy process, need to guarantee that chevilled silk spacing 13 is 0; The focus of laser beam is positioned on the 2XXX aluminium alloy plate on 1, and laser side-play amount 14 is between 0.2-0.7mm.

In the laser beam welding, laser 3 acts on filler wire and the aluminium alloy plate to be welded (1 and 2) simultaneously, because the laser high energy density; Wire melting in interaction region, the aluminium alloy plate fusing also welding plasma 7, molten deeply aperture occur, and a large amount of physics, chemical change have taken place; Along with the motion of laser, molten deeply aperture constantly, stably form, the welding wire of fusing is constantly filled and is got into the molten bath; And the liquid bath temperature that leaves laser beam constantly reduces, and is frozen into weld seam 6.

When laser weld 2XXX and 7XXX series heterogeneity aluminum alloy, need make the chevilled silk spacing is 0mm.Because at this moment the contact position in welding wire and molten bath just is the laser beam application point, the welding wire-molten drop of fusing will contact transition with generation between the molten bath stably in the interaction area of laser and material under the effect of various power.Molten bath kept stable in the welding process can obtain uniform appearance of weld.When the chevilled silk spacing is big,, improved the probability that forms defectives such as pit in the welding process because most of energy of laser makes the too high unstability that increases welding process of energy on the mother metal on base metals.

In order to guarantee the stability of welding process; When laser weld 2XXX and 7XXX series heterogeneity aluminum alloy; Generally making the focus of laser beam is not the center that is positioned at weld seam, but is positioned on the 2XXX aluminium alloy plate, and the distance at weld seam center is that side-play amount is generally between 0.2-0.7.Because the subject matter of laser weld 2XXX series alloy is fire check and pore, welding process is more stable, for the offset of stabilized welding process laser spot on the 2XXX series alloy.If side-play amount is excessive, weld metal solidify substantial deviation weld seam center, center, the frozen metal can not cover the port of 7XXX series, causes weldquality to descend.If the focus of laser beam is positioned at the center of weld seam or to the skew of 7XXX series, the unstability of 7XXX series alloys laser beam welding will influence the quality of connection of 2XXX and 7XXX series heterogeneity aluminum alloy.

Except that above-mentioned parameter, in the process of welding, also need regulate laser power, speed of welding and wire feed rate and come accurately control sweating heat input quantity, realize being connected of 2XXX series and 7XXX series heterogeneity aluminum alloy.The working gas that adopts in the welding process is a helium, and the feeding direction of working gas is consistent with welding direction.

The welding process that laser adds silk is a melting process; Weld seam has experienced the process of fusing, rapid solidification; Caused to organize with hardening constituent in the weld seam and changed; Be prone to the evaporated metal element loss in the high temperature action lower part, welding heat affected zone also can change in heat effect undertissue and hardening constituent, has caused between Weld Performance and the mother metal difference to occur.In the process of welding, add Al-Si and Al-Cu welding wire, not only can be in weld seam the easy evaporation element of replenish lost, also can generate hardening constituent such as θ (Al ₂Cu) phase, Mg2S equate, thereby improve the mechanical performance of welding point.

Description of drawings

Fig. 1 connects 2XXX and 7XXX heterogeneity aluminum alloy experiment sketch map in succession for wire filling laser welding

Fig. 2 connects 2XXX and 7XXX heterogeneity aluminum alloy sectional view in succession for wire filling laser welding

Fig. 3 laser side-play amount sketch map

Fig. 4 connects 2XXX and 7XXX heterogeneity aluminum alloy weld seam pattern (a) and cross section (b) in succession for wire filling laser welding

Fig. 5 is for filling 2319 welding wire weld seam stress strain curves

Fig. 6 is for filling 4043 welding wire weld seam stress strain curves

Fig. 7 is for filling 2319 and 4043 welding wire weld seam fracture characteristics

Fig. 8 is for filling the weld seam fracture apperance of 2319 welding wires

Fig. 9 is for filling the weld seam fracture apperance of 4043 welding wires

Among the figure, the 1-2XXX mother metal; The 2-7XXX mother metal; The 3-laser beam; 4-protects gas jets; The 5-wire feeding mouth; The 6-weld seam; 7-welds plasma; The 8-welding direction; 9-welds aperture; 10-wire feed angle; 11-protection air horn degree; The 12-incidence angle; 13-chevilled silk spacing; 14-laser side-play amount;

The specific embodiment:

Mode 1:

Use diameter when being welded to connect 2024 and 7075 heterogeneity aluminum alloys,, to be assembled into the banjo fixing butt jointing of Fig. 1 at first with material 2024 to be welded and 7075 surface clean as packing material as the AlCu welding wire (the welding wire trade mark is 2319) of 1.2mm; Wherein laser beam 3, wire feed nozzle 5 are fixed in the same plane with protection gas jets 4; Wire feed nozzle 5 lays respectively at the both sides (wire feed angle and protective gas angle are respectively 45 ° and 55 °) of laser beam 3 with protecting gas jets 4, and laser beam 3 is incident to material surface to be welded (1 and 2) with incidence angle 12 (10 °), and chevilled silk spacing 13 is 0; The focus of laser beam is positioned on the 2XXX aluminium alloy plate on 1; Laser side-play amount 14 is at 0.5mm, and the parameter of laser weld is laser power 3500W, speed of welding 4m/min; Wire feed rate 3.5m/min carries out under these conditions that laser is Wire-added to be connect.The weld seam and the cross-sectional view that obtain are Fig. 4.

Mode 2:

Use diameter when being welded to connect 2024 and 7075 heterogeneity aluminum alloys,, to be assembled into the banjo fixing butt jointing of Fig. 1 at first with material 2024 to be welded and 7075 surface clean as packing material as the AlCu welding wire (the welding wire trade mark is 2319) of 1.2mm; Wherein laser beam 3, wire feed nozzle 5 are fixed in the same plane with protection gas jets 4; Wire feed nozzle 5 lays respectively at the both sides (wire feed angle and protective gas angle are respectively 45 ° and 55 °) of laser beam 3 with protecting gas jets 4, and laser beam 3 is incident to material surface to be welded (1 and 2) with incidence angle 12 (10 °), and chevilled silk spacing 13 is 0; The focus of laser beam is positioned on the 2XXX aluminium alloy plate on 1; Laser side-play amount 14 is at 0.5mm, and the parameter of laser weld is laser power 3500W, speed of welding 4m/min; Wire feed rate 3.5m/min carries out under these conditions that laser is Wire-added to be connect.

Be processed into tensile sample to above-mentioned weldment, adopt the weld seam average tensile strength 339.5MPa of 2319 welding wires, the weld seam average tensile strength that adopts 4043 welding wires is 308.6.Adopt the stress strain curve figure of 2319 and 4043 welding wire weld seams closely similar, Fig. 5 and 6 is respectively two kinds of welding wire stress strain curve figure.Laser welded seam is narrow; Weld width is less than 2mm in this experiment, and the heat affected area is also very little, and the material outside weld seam and the heat affected area has kept good intensity of former mother metal and toughness; Because weld strength is less than mother metal, so on stress strain curve, be difficult to embody the percentage elongation of weld seam part.

Two groups of fracture site have bigger difference; (Fig. 7 a) shows that the weld seam fracture is neat to adopt the weld seam vertical view of 2319 welding wires; See that from section of weld joint figure (Fig. 7 b) first half fracture occurs near fusion area or the heat affected area; Basically be positioned at jump welding and sew up head portion, the fracture of weld seam middle and lower part occurs in the weld seam center, and such fracture runs through the whole welding line fracture.Adopt the weld seam of 4043 welding wires to see the fracture position irregular from vertical view (Fig. 7 ac); Section of weld joint figure (Fig. 7 d) cleaved is tiltedly worn the whole welding line cross section; Weld seam each several part fracture difference is obvious, and some areas fracture betides the weld seam fracture that the melt run place forms similar employing 2319 welding wires.

Fig. 8 is for filling 2319 welding wire weld seam stretching fracture shape appearance figures; Some areas are distributing and are having the dimple of obvious ductile rupture characteristic; Some areas distribute can see the ridge columnar fracture that under the cleavage fracture pattern, produces, so this is the fracture that a kind of ductile rupture and cleavage fracture mode mixture exist.

It is as shown in Figure 9 to fill 4043 welding wire weld seam stretching fracture patterns, and the fracture size dimple comparatively uniformly that distributing is the fracture that a kind of ductile rupture forms.

Claims (2)

1. a laser fills silk and connects the method for 2XXX and 7XXX series heterogeneity aluminum alloy, and it is characterized in that: material surface to be welded at first is assembled into banjo fixing butt jointing with two kinds of aluminium alloy plates to be welded after cleaning; Wherein laser beam, wire feed nozzle are fixed in the same plane with the protection gas jets, and the wire feed nozzle lays respectively at the both sides of laser beam with protecting gas jets, and laser beam incident is to surface of steel plate, and incidence angle is the angle of laser beam and vertical direction, between 0-15 °; Angle between aluminium alloy welding wire and the mother metal surface is the wire feed angle, between 45-60 °; Angle between protection gas jets and the mother metal surface is protection air horn degree, between 45-55 °;

The fall spacing of silk point and laser spot of aluminium alloy welding wire is the chevilled silk spacing, guarantee during welding that laser spot is put with the silk that falls of aluminium alloy welding wire and protective gas send into consistently, promptly the chevilled silk spacing is 0; Laser spot is that the laser side-play amount is between 0.2-0.7mm to the vertical range of butt joint aluminium alloy weld seam; The focus of laser beam is positioned on the 2XXX aluminium alloy plate 1;

The scope that in the process of welding, also need regulate laser power is 3.0-3.5kW, and the scope of speed of welding is 3.0-5.0m/min, and the scope of wire feed rate is 2.5-4.0m/min; Welding process need guarantee aluminium alloy welding wire send into direction and welding direction is opposite, welding process adopts helium to do protective gas; The welding wire of sending into the weld zone is AlSi or AlCu welding wire, and diameter is between 0.8-1.2mm.

2. according to the said method of claim 1, it is characterized in that: LASER Light Source is CO ₂, Nd:YAG or optical-fiber laser any one.

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