JPH0623546A - Padding method by welding for al or al-base material - Google Patents

Abstract

PURPOSE:To provide the padding method by welding capable of stably obtaining wear resistant and heat resistant padding by welding with high jointability with a base material without causing welding defects such as pits and blowholes on the Al or Al-base material surface. CONSTITUTION:In the padding method by welding by two electrodes, a preceding DCEP-MIG welding zone is remelted and welded by succeeding TIG welding. A Cu-Al flux-cored wire formed by filling up a core material wire made of Al-base material in a hollow part of sheath material made of Cu-base material and having the Cu quantity of 30-85weight% for the wire total weight is used for an electrode wire 11 of DCEP-MIG welding. Further, the distance between a preceding DCEP-MIG welding electrode wire 1 and a succeeding TIG welding electrode 2 is made to 50-400mm and cladding by welding for the Al or Al-base material is performed. Consequently, the occurrence of the welding defects such as pits and blowholes is reduced and the Al or Al-base material surface is imparted with wear resistance and heat resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a build-up welding method for imparting wear resistance and heat resistance to the surface of Al and Al-based materials, and particularly to obtain a build-up weld metal with few welding defects such as pits and blow holes. It is about the method.

[0002]

2. Description of the Related Art Al and Al-based materials are used in a wide range of fields including automobile parts because they are lighter in weight and have better thermal conductivity and corrosion resistance than steel materials. However, Al, Al-based material alloys are generally inferior to steel materials in terms of strength, wear resistance, and heat resistance, and the raw materials themselves are limited in the parts and parts that can be applied as substitute materials for steel materials. A method of forming a hard layer on the surface of Al or an Al-based material has been studied. As a method,
PVD, CVD method for forming a thin hard coating layer,
A method of forming a relatively thick hard coating layer by thermal spraying, a method of forming a hard alloying layer by melting an alloying metal with a substrate surface using a high-density energy source such as an electron beam or a laser, MIG arc, TIG arc There is a method of forming a hard overlay metal by using.

Among these, as a build-up welding method for Al and Al alloys using MIG arc and TIG arc, Japanese Patent Laid-Open No. 58-58
Japanese Patent Publication No. 179569 discloses a method of surface hardening an Al-based material by TIG arc using a mixed powder of Al or Al alloy powder and NbC powder, TiC powder, and VC powder as a filler material. However, when powder is used as the filler metal, there are problems such as stable feeding of the filler metal and segregation of the composition, and it is difficult to obtain a built-up metal having a uniform composition. For example, NbC,
In a mixed powder of ceramics such as TiC powder and Al alloy powder, ceramics such as carbides are generally crushed powders and are irregular shaped powders, so stable feeding is difficult, and mixed powders with different specific gravities have a uniform composition. Delivery is difficult. Therefore,
Since the dilution amount of the added metal varies, the composition of the overlay metal obtained becomes non-uniform, which causes variations in characteristics such as wear resistance and heat resistance.

Further, JP-A-3-169495,
Japanese Unexamined Patent Publication (Kokai) No. 3-169496 discloses an Al surface hardening method using a composite filler material in which a metal wire rod or a ceramic wire rod other than Al is contained in an Al sheath. When a composite wire is used as the filler material, if the melting point of the core material enclosed inside the envelope metal is higher than the melting point of the envelope metal, the envelope metal melts first, and then the encapsulated core material melts. Become. When such a phenomenon occurs, segregation of the components is liable to occur in the build-up metal, such as a place where the outer layer metal component is large and a place where the core material component is large in the alloy layer, and it is difficult to obtain the build-up metal in a uniform composition.

On the other hand, even in the overlay welding on the surface of Al or Al-based material, as in the welding of Al or Al-based material, it is easy to absorb H ₂ , N ₂ , O _2, etc. in the molten state, so that pits, blow holes, etc. The welding defect is easily generated, and the gas component brought from the filler metal is a major factor in the generation thereof. Weld defects such as pits and blowholes generated on the surface and inside of the overlay are generally due to hydrogen. As the hydrogen source, hydrogen due to decomposition of moisture, organic matter, corrosion products, etc. adhering to or adsorbed on the base material and the welding wire, hydrogen dissolved in the base material and the welding wire, hydrogen in the shield gas and It is thought that the cause is water, ambient air trapped in the arc atmosphere, and the like. Also A
1. An oxide film (Al ₂ O ₃ ) is easily formed on the surface of the Al-based material, which is caught during welding and causes pits and blow holes. Furthermore, oxide film (Al ₂ O ₃ )
Is generated at a temperature of 2000 ° C. or higher during welding, the blowhole may be trapped in the weld metal by the oxide film.

Therefore, the following techniques have been proposed as a method for reducing pits and blow holes. For example, JP-A-55-86696 discloses that water, organic substances, corrosion products, and oxide films adhering to the wire surface are removed by a mechanical grinding device immediately before welding, or an alkaline cleaning device is provided to chemically remove them. By removing it, pits and blow holes are reduced. In addition, JP-A-58-154
According to Japanese Patent No. 461, AC (alternating current) -TIG or DCEP (direct current electrode plus) -TIG is provided between wire feeding cables.
A wire oxide film removal cleaning device is installed. However, all of these techniques remove water, organic substances, corrosion products, and oxide films adhering to the wire to reduce pits and blow holes, and water, organic substances adhering to the base metal, It is not sufficient to prevent pits and blowholes caused by corrosion products, oxide films, and gas components in the base metal.

Further, in Japanese Patent Laid-Open No. 51-1339, A
The C-TIG method or the DCEP-TIG method is preceded to reduce the amount of hydrogen diffused in the weld metal by its preheating effect and to remove the oxide film of the base metal by utilizing the arc cleaning action. (DC electrode minus)
-Welding is performed by the TIG method to obtain a sound weld metal without pits and blow holes. As a similar technique, in Japanese Unexamined Patent Publication No. 53-29245, the DCEP-TIG method is preceded, the base material is melted to remove gas components in the base material, and immediately after that, the AC-TIG method is used for welding to form a surface pit. It has been resolved. These techniques are methods in which water and oxides on the surface of the base material and gas components in the base material are removed by the preceding electrode, and then a filler wire is inserted into the electrode of the subsequent electrode to perform welding. Water, pits caused by oxides,
It is not sufficient to prevent pits and blowholes caused by water in the air brought into the molten pool by blowholes and filler wires.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems in the method of reducing pits and blowholes, and its object is to:
It is an object of the present invention to provide a welding method in which welding defects such as pits and blow holes do not occur and a sound overlay welded portion can be obtained.

[0009]

The welding method of the present invention has the following structure. That is, in the overlay welding method using two electrodes, the preceding DCEP-MIG welded portion is remelted and welded by the following TIG welding, and DCEP-MIG welding is performed.
In the MIG welding electrode wire, the hollow part of the outer cover material made of Cu base material is filled with the core wire made of Al base material, and C
C in which the amount of u is 30 to 85% by weight based on the total weight of the wire
Using u-Al composite wire and prior DCEP-MI
The distance between the G welding electrode wire and the subsequent TIG electrode is 50 to
The overlay welding method for Al and Al-based materials is characterized in that the thickness is 400 mm.

[0010]

The present invention will be described in detail below with reference to the drawings.
FIG. 1 is a vertical sectional view showing the method of the present invention. The leading electrode is the electrode wire (1) for DCEP-MIG welding,
Ar gas (5) sprayed as a shield gas has a cleaning action of ionizing in the MIG arc (7) and hitting the base material surface (9) to remove an oxide film.
In addition, the welding speed is high and welding can be performed at high speed. In DCEN (minus direct current electrode) -MIG welding, since there is no cleaning action on the surface of the base metal, it becomes impossible to perform sound welding under the influence of the oxide film on the surface of the base metal. To arrange the TIG torch (4) on the trailing electrode is a DCEP-
In MIG welding, the surrounding air is entrained and the water in the air may induce pits and blow holes, so the TIG arc (8) of the trailing electrode is used to re-build the overlay metal (10) obtained by DCEP-MIG welding. This is for removing the pits and blow holes generated in the overlay metal by melting.

Furthermore, DCEP-MIG electrode wire (1)
The distance between the TIG electrode and the TIG electrode (2) is preferably 50 to 400 mm. When the thickness is 50 to 400 mm, mutual interference of arcs can be eliminated, and the overlay metal (10) obtained by DCEP-MIG welding can be remelted. If the distance between both electrodes is less than 50 mm, mutual arcs will occur and stable welding cannot be performed. If it exceeds 400 mm, DCE
Since the temperature of the overlay metal (10) obtained by P-MIG welding drops, the preheating effect disappears and the overlay metal (10) cannot be sufficiently melted by the TIG arc (8), so that it is not melted. There are pits and blow holes left in the section. Further, since the device itself becomes large, operability also deteriorates.

Further, in the electrode wire (1), a core material wire made of an Al base material is filled in a hollow portion of an outer skin material made of a Cu base material, and the amount of Cu is 30 to 85% by weight based on the total weight of the wire.
Is used. When the outer skin metal has a higher melting point than the core metal, that is, when the outer skin is a Cu-based material and the core material is an Al-based material, a good overlay metal can be obtained because the alloyed droplets migrate, When the outer metal has a lower melting point than the core metal, that is, when the outer metal is an Al-based material and the core material is a Cu-based material, the outer metal has a low melting point and is melted first by arc heat or Joule heat. As a result, the quality of the overlay metal is not stable because the alloy remains unmelted, the alloying does not proceed well, and the hardness of the overlay metal fluctuates.

Further, the hardness of the overlay metal, which is obtained with stable wear resistance of the overlay metal, needs to be Vickers hardness Hv150 or more, and if it is less than Hv150, improvement of the abrasion resistance is not expected. The structure of the overlay metal formed by the Al-Cu composite wire is composed of an α phase and a θ phase (CuAl ₂ ) on the high Cu side, and has wear resistance and heat resistance due to the existence of the θ phase. That is, when the amount of Cu is less than 30%, the amount of Cu of the overlay metal obtained by welding becomes insufficient, and almost only the α phase is formed, and the hardness thereof does not reach Hv150 and is not suitable for a wear resistant material. On the other hand, when the Cu content exceeds 85%, a brittle η ₂ phase appears and cracking occurs. Therefore, Cu in which the core wire made of Cu base material is filled in the outer skin made of Al base material
The Cu content of the -Al composite wire needs to be in the range of 30 to 85%. Examples will be shown below.

[0014]

【Example】

Example 1 A welding test was conducted on a base material according to JIS A 5083P: 10t × 5.
0w × 150l is used, and the Cu electrode is Al-C with a Cu content of 70 wt% for the preceding electrode (DCEP: direct current electrode plus).
u composite wire (1.2 mm) with DCEN for the trailing electrode
(DC electrode minus) -TIG method was used to perform welding by the bead-on-plate method, and the reduction state of blowholes in the bead cross section obtained was investigated. For the reduction of blowholes, the weld bead was cut into 5 cross sections, each cross section was finished by buffing with 1 μm diamond grains, and the cross section of the obtained bead was taken with an optical microscope (20 times). The blowhole total area and the overlay metal area were measured from an image of the shape with an image analyzer, and the blowhole area ratio (total blowhole area / overlay metal area) was obtained and evaluated. The hardness was measured with a Vickers hardness meter at a pitch of 0.5 mm from the bead surface in the center of the transverse cross section of the weld bead to the melting boundary, and the average value of the hardness was determined. For the presence or absence of cracks in the overlay metal, examine the weld bead cross section with an optical microscope (× 10
Observed at 0). The welding conditions are shown below.

The distance between the leading electrode and the trailing electrode is 40, 1.
It was changed to 00 and 500 mm. Welding condition Leading electrode Trailing electrode DCEP-MIG electrode DCEN-TIG electrode Welding current 140A Welding current 120A Arc voltage 21V Arc voltage 16V Welding speed 40cm / min Welding speed 40cm / min Shield gas Ar: 25l / min Shield gas He: 25l / min Wire protrusion length 15 mm

Table 1 shows the blowhole area ratio of the bead cross section welded only with the leading electrode, the blowhole area ratio of the bead cross section welded by changing the gap between the leading electrode and the trailing electrode,
The result of hardness cracking is shown. Further, FIG. 2 shows a bead cross-section macro (A) welded only with the leading electrode and a bead cross-section macro (B) welded with the leading electrode and the trailing electrode.

[0017]

[Table 1]

From Table 1, there are many blowholes in the bead (A) welded only with the leading electrode (DCEP), but the bead (C) welded with the leading electrode (DCEP) + the trailing electrode (DCEN). Blowhole is about 1/10
Decreased to. When the gap between the electrodes was 40 mm (B), the arcs interfered with each other and welding could not be performed. The distance between the poles is 500m
In the case of m (D), the bead welded by the leading electrode was cooled and could not be sufficiently remelted by the trailing electrode, so the effect of reducing the blowhole area ratio was less than that of 100 mm between the electrodes. The hardness was Hv250 to 280, which was sufficient from the viewpoint of wear resistance, and there was no cracking.

Example 2 In the welding test, the base metal was JIS A 5083P: 10t × 5.
0w × 150l is used, and the amount of Cu in the preceding electrode (DCEP: DC electrode plus) is 25, 60, and 90 wt, respectively.
% Cu sheath Al-Cu composite wire (1.2 mm) and C
An Al-clad Al-Cu composite wire with an u amount of 60 wt%
The AC (AC) -TIG method was used for the trailing electrode to perform welding by the bead-on-plate method, and the area ratio of blowholes in the cross section of the bead, the average hardness, and the variation in hardness were investigated. The blowhole area ratio and hardness were measured by the same method as in Example 1, and the variation in hardness was expressed in the range between the maximum and minimum values of hardness. The welding conditions are shown below.

Welding condition Leading electrode Trailing electrode DCEP-MIG electrode AC-TIG electrode Welding current 140A Welding current 120A Arc voltage 21V Arc voltage 12V Welding speed 40cm / min Welding speed 40cm / min Shielding gas Ar: 25l / min Shielding gas Ar : 25 l / min Wire protrusion length 15 mm Table 2 shows the blowhole area ratio, hardness, and bead breakage.

[0021]

[Table 2]

From Table 2, (E) having a Cu content of 25 wt% has a low hardness of Hv110 and is inferior in wear resistance. Cu
When the amount was 60 wt%, the hardness was Hv223 and there was no crack and it was good. When the amount of Cu was 90 wt%, the hardness was high at Hv368, and the bead cracked. Cu with Al core and core
In the Al-Cu composite wire (H), the hardness of the overlay metal varies greatly, and a overlay metal with stable hardness cannot be obtained. still,
The blowhole area ratio was small and good.

[0023]

As described above, according to the method of the present invention, it is possible to obtain a build-up metal which is less likely to cause welding defects such as pits and blow holes, and which imparts wear resistance and heat resistance to the surfaces of Al and Al-based materials. .

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a method of the present invention,

FIG. 2 is a view showing a bead cross-section macro (A) welded only with a leading electrode and a bead cross-section macro (B) welded with a leading electrode and a trailing electrode.

[Explanation of symbols]

 1 Electrode Wire 2 TIG Electrode 3 MIG Torch 4 TIG Torch 5 Ar Gas 6 Shielding Gas 7 MIG Arc 8 TIG Arc 9 Base Material 10 Overlay Metal 11 Between Electrodes

Front Page Continuation (72) Inventor Yoshio Kobe 3-5-4 Tsukiji, Chuo-ku, Tokyo Nittetsu Welding Industry Co., Ltd. Research Institute

Claims (3)

[Claims] 1. A build-up welding method using a two-electrode, wherein the preceding DCEP-MIG welded portion is remelted and welded by a subsequent TIG welding, and the build-up welding is performed on the surface of an Al or Al-based material. Method. 2. An electrode wire for DCEP-MIG welding is prepared by filling a hollow part of an outer cover material made of a Cu base material with a core wire made of an Al base material, the Cu content being 30 to 85 with respect to the total weight of the wire. The overlay welding method for forming an Al or Al-based material according to claim 1, wherein a Cu-Al composite wire whose content is wt% is used. 3. The Al according to claim 1 or 2, wherein the distance between the electrode wire of the preceding DCEP-MIG welding and the following TIG electrode is 50 to 400 mm.
Overlay welding method on Al-based material.