JP3075842B2 - Overlay welding method to Al, Al base material - Google Patents

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 abrasion resistance and heat resistance to the surface of Al and Al-based materials, and in particular, to obtain a build-up weld metal with less occurrence of 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 of their light weight, excellent thermal conductivity and excellent corrosion resistance as compared with steel materials. However, Al, Al-based material alloys are generally inferior in strength, abrasion resistance, and heat resistance as compared with steel materials, and the parts and parts that can be used as substitutes for steel materials are limited as they are, A method of forming a hard layer on the surface of Al or an Al-based material has been studied. As a method,
A method of forming a thin hard coating layer by PVD, CVD,
A method of forming a relatively thick hard coating layer by thermal spraying, a method of forming a hard alloyed layer by melting an alloyed metal together with a substrate surface using a high-density energy source such as an electron beam or a laser, MIG arc, TIG arc And a method of forming a hardfacing metal using the method.

[0003] Among them, a method of overlay welding of Al and Al alloy using MIG arc and TIG arc is disclosed in
Japanese Patent Application Publication No. 179569 discloses a method of surface hardening an Al-based material by a TIG arc using a mixed powder of Al or an Al alloy powder and NbC powder, TiC powder, and VC powder as a filler material. However, when powder is used as the filler material, there are problems such as stable feeding of the filler material and segregation of the composition, and it is difficult to obtain a build-up metal having a uniform composition. For example, NbC,
In the mixed powder of ceramics such as TiC powder and Al alloy powder, ceramics such as carbide are generally crushed powders and therefore irregular shaped powders, so that stable feeding is difficult, and in the case of mixed powders having different specific gravities, the composition is uniform. Delivery is difficult. Therefore,
Since the amount of dilution of the added metal fluctuates, the composition of the resulting build-up metal becomes non-uniform, which causes fluctuations in properties such as wear resistance and heat resistance.

Further, Japanese Patent Laid-Open No. 3-169495,
Japanese Patent Application Laid-Open No. 3-169496 discloses a method for hardening Al using a composite filler material in which a metal wire other than Al or a ceramic wire is housed in an Al shell. When the composite wire is used as the filler material, if the melting point of the core material included in the outer metal is higher than the melting point of the outer metal, the outer metal will melt first, and then the inner core will melt. Become. When such a phenomenon occurs, segregation of components is likely to occur in the build-up metal, such as a place where the outer layer metal component is large in the alloy layer and a place where the core material component is large, and it is difficult to obtain the build-up metal with a uniform composition.

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

Therefore, the following technique has been proposed as a method for reducing pits and blowholes. For example, Japanese Unexamined Patent Publication No. 55-86669 discloses that moisture, organic matter, corrosion products, and oxide films adhering to the surface of a wire are removed by providing a mechanical grinding device immediately before welding, or by providing an alkaline cleaning device and chemically removing the oxide film. By removing them, pits and blowholes are reduced. Also, Japanese Patent Application Laid-Open No. 58-154
No. 461 discloses an AC (AC) -TIG or DCEP (DC electrode plus) -TIG between wire feeding cables.
And a wire oxide film removal cleaning device is provided. However, all of these technologies remove moisture, organic matter, corrosion products, and oxide films attached to the wire to reduce pits and blowholes, and reduce moisture, organic matter, It is not enough to prevent pits and blowholes caused by corrosion products, oxide films, and gas components in the base material.

In Japanese Patent Application Laid-Open No. 51-1339, A
Prior to the C-TIG method or the DCEP-TIG method, the preheating effect reduces the amount of diffused hydrogen in the weld metal, removes the oxide film of the base metal by utilizing the arc cleaning action, and immediately thereafter, the DCEN (DC electrode minus)
-Welding by TIG method to obtain sound weld metal without pits and blowholes. As a similar technique, Japanese Unexamined Patent Publication No. 53-29245 discloses a method in which a DCEP-TIG method is preceded, a base material is melted, gas components in the base material are removed, and immediately thereafter, welding is performed by an AC-TIG method to perform surface pitting. Has been eliminated. These techniques involve removing the moisture and oxides on the surface of the base material and gas components in the base material with the preceding electrode, and then inserting a filler wire into the succeeding electrode for welding. Pits caused by moisture, oxides,
It is not enough to prevent pits and blowholes caused by moisture 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 problems in the method for reducing pits and blowholes as described above.
An object of the present invention is to provide a welding method in which a welding defect such as a pit or a blowhole does not occur and a sound overlay weld can be obtained.

[0009]

SUMMARY OF THE INVENTION The welding method of the present invention has the following constitution. That is, in the overlay welding method using two electrodes, the preceding DCEP-MIG welding portion is re-melted and welded by the subsequent TIG welding, and the DCEP-MIG welding is performed.
-The electrode wire of MIG welding is filled with a core wire made of an Al-based material in a hollow portion of a skin material made of a Cu-based material,
C whose u amount is 30 to 85% by weight based on the total weight of the wire
U-Al composite wire and prior DCEP-MI
The distance between the electrode wire for G welding and the subsequent TIG electrode should be 50-
This is a method for overlay welding to Al or an Al-based material, characterized in that the thickness is 400 mm.

[0010]

The present invention will be described below in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing the method of the present invention. The leading electrode is an electrode wire (1) for DCEP-MIG welding.
Ar gas (5) injected as a shielding gas is ionized in the MIG arc (7) and has a cleaning action of removing an oxide film on the base material surface (9);
In addition, the welding speed is high, and welding can be performed at a high speed. In DCEN (DC electrode minus) -MIG welding, there is no cleaning action on the surface of the base material, so that sound welding cannot be performed due to the influence of the oxide film on the surface of the base material. The arrangement of the TIG torch (4) on the trailing electrode is based on DCEP-
In MIG welding, the surrounding air may be entrained, and moisture in the air may induce pits and blow holes. This is for removing pits and blow holes generated in the overlay metal by melting.

Further, a DCEP-MIG electrode wire (1)
The distance between the TIG electrode (2) and the TIG electrode (2) is preferably 50 to 400 mm. By setting the thickness to 50 to 400 mm, interference between arcs can be eliminated, and the overlay metal (10) obtained by DCEP-MIG welding can be re-melted. If the gap between the two electrodes is less than 50 mm, interference between the arcs will occur and stable welding cannot be performed. In addition, DCE exceeds 400 mm
Since the temperature of the overlay metal (10) obtained by the P-MIG welding drops, the preheating effect is lost and the overlay metal (10) cannot be sufficiently melted by the TIG arc (8), so that it is not melted. Pit and blowhole remain in the part. In addition, operability is deteriorated because the device itself becomes large.

Further, the electrode wire (1) is filled with a core wire made of an Al-based material in a hollow portion of a shell material made of a Cu-based material, and the Cu content is 30 to 85% by weight based on the total weight of the wire.
Is used. If the shell metal has a higher melting point than the core metal, that is, if the shell is a Cu-based material and the core is an Al-based material, a good overlay metal is obtained because the alloyed droplets migrate, When the shell metal has a lower melting point than the core metal, that is, when the shell is an Al-based material and the core material is a Cu-based material, the melting point of the shell metal is low, so that the core metal is first melted by arc heat or Joule heat. However, the quality of the build-up metal is not stable, for example, the alloying cannot proceed well and the hardness of the build-up metal fluctuates.

[0013] The hardness of the build-up metal, which can stably obtain the wear resistance of the build-up metal, must be Vickers hardness Hv150 or more, and if it is less than Hv150, no improvement in wear resistance is expected. The structure of the build-up metal 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 presence of the θ phase. That is, if the Cu content is less than 30%, the Cu content of the overlay metal obtained by welding is insufficient, and almost only the α phase is present, and the hardness does not reach Hv150, which 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 cracks occur. Therefore, Cu filled with a core wire made of a Cu base in an outer skin made of an Al-based material
-The Cu content of the Al composite wire must be in the range of 30 to 85%. Examples will be described below.

[0014]

【Example】

Example 1 In the welding test, JIS A 5083P: 10 t × 5
Using 0 w × 150 l, the outer electrode (DCEP: DC electrode plus) has a Cu shell Al-C with a Cu content of 70 wt%.
u composite wire (1.2 mm) and DCEN
(DC electrode minus) Using the TIG method, the reduction of blowholes in the cross section of the bead obtained by welding by the bead-on-plate method was investigated. The blow hole was reduced by cutting the weld bead into 5 cross-sections, finishing each cross-section by buffing with 1 μm diamond grains, and photographing with an optical microscope (20 ×). From the photograph of the shape, the total area of the blowhole and the area of the buildup metal were measured by an image analyzer, and the blowhole area ratio (total area of the blowhole / total area of the buildup metal) was determined and evaluated. The hardness was measured using a Vickers hardness meter at a 0.5 mm pitch from the center bead surface of the transverse cross section of the weld bead to the fusion boundary, and the average value of the hardness was determined. The presence or absence of cracks in the build-up metal was determined by examining the cross section of the weld bead using an optical microscope (× 10
0). The welding conditions are shown below.

The distance between the leading electrode and the trailing electrode is 40, 1
00 and 500 mm. Welding conditions 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 Shielding gas Ar: 25l / min Shielding gas He: 25l / min Wire protrusion length 15mm

Table 1 shows the blow hole area ratio of the bead cross section welded only with the leading electrode, the blow hole area ratio of the bead cross section welded by changing the gap between the leading electrode and the trailing electrode,
The results of hardness cracking are shown. FIG. 2 shows a bead cross-sectional macro (A) welded with only the leading electrode and a bead cross-sectional macro (B) welded with the leading and trailing electrodes.

[0017]

[Table 1]

According to Table 1, the bead (A) welded with only the leading electrode (DCEP) has many blowholes, but the bead (C) welded with the leading electrode (DCEP) + the trailing electrode (DCEN). Is about 1/10 of blowhole
Decreased to. When the distance between the electrodes was 40 mm (B), the arcs interfered and welding could not be performed. 500m between poles
In the case of (m), since the bead welded by the preceding electrode was cooled and could not be sufficiently re-melted by the succeeding electrode, the effect of reducing the blowhole area ratio was less than 100 mm between the electrodes. The hardness was Hv250 to 280, which was sufficient from the viewpoint of wear resistance, and there was no crack.

Example 2 In the welding test, JIS A 5083P: 10 t × 5
Using 0 w × 150 l, the amount of Cu was 25, 60, and 90 wt% for the leading electrode (DCEP: DC electrode plus), respectively.
% Cu sheath Al-Cu composite wire (1.2 mm) and C
An Al sheath Al-Cu composite wire having a u content of 60 wt%
The following electrode was subjected to welding by a bead-on-plate method using an AC (AC) -TIG method, and the area ratio, average hardness, and variation in hardness of blow holes in a bead cross section obtained by welding were investigated. The blowhole area ratio and hardness were measured in the same manner as in Example 1, and the variation in hardness was expressed in the range of the maximum value and the minimum value of hardness. The welding conditions are shown below.

Welding conditions 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 blow hole area ratio, hardness, and the state of bead cracking.

[0021]

[Table 2]

According to 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, which was good without cracking. When the Cu content was 90 wt%, the hardness was high at Hv368, and cracks occurred in the beads. The core is Cu with Al skin
In the Al-Cu composite wire (H), the hardness of the build-up metal varies greatly, and a build-up metal with a 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 has less occurrence of welding defects such as pits and blowholes and imparts abrasion resistance and heat resistance to the surface of Al or Al-based material. .

[Brief description of the drawings]

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

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

[Explanation of symbols]

 DESCRIPTION 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 metal 10 Overlay metal 11 Between poles

──────────────────────────────────────────────────続 き Continuation of the front page (72) Yoshio Kobe, Inventor, Nippon Steel Welding Industry Co., Ltd. Researcher, 3-5-4 Tsukiji, Chuo-ku, Tokyo (56) Reference JP-A-53-34653 (JP, A) 52-8941 (JP, A) JP 51-21604 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/04 B23K 9/16 B23K 35/02 B23K 35/18 B23K 103: 10

Claims (3)

(57) [Claims] 1. A cladding welding method using two electrodes, wherein a preceding DCEP-MIG weld is re-melted and welded by a subsequent TIG welding to a surface of an Al or Al-based material. Method. 2. An electrode wire for DCEP-MIG welding is filled with a core wire made of an Al-based material in a hollow portion of a shell material made of a Cu-based material, and the Cu content is 30 to 85 with respect to the total weight of the wire. 2. The method for overlay welding on Al and Al-based materials according to claim 1, wherein a Cu-Al composite wire having a weight percentage of Cu is used. 3. A method according to claim 1, wherein the distance between the electrode wire of the preceding DCEP-MIG welding and the subsequent TIG electrode is 50 to 400 mm.
Overlay welding method to Al-based material.