JP3107602B2 - Welding method of aluminum material with improved weld cracking - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding method used for manufacturing vehicles, ships, tanks, and other aluminum welded structures, and more particularly, to a welding method that produces a cleaning action during welding such as TIG welding. The present invention relates to a method for welding an aluminum material with improved weld cracking in an affected zone.

[0002] In this specification, the term aluminum is used to mean its alloy.

[0003]

2. Description of the Related Art Generally, AC welding is used for welding aluminum materials.
-TIG welding or the like is used. This is because the presence of an oxide film poses a problem in the welding of aluminum material, but in TIC welding or the like, a cleaning action occurs during welding to remove the oxide film around the welded metal portion, resulting in a beautiful surface.

[0004]

However, when the aluminum material is subjected to TIG welding or the like as described above, a small crack may be generated in the heat affected zone (HAZ portion). In particular, when the aluminum material is an extruded material having a coarse surface recrystallization reaching a thickness of, for example, about 100 μm or more, particularly, the welding heat input is excessive and the joint shape has a heat like a T-shaped fillet. If the structure is such that stress is easily applied to the affected area, there is a disadvantage that micro-cracks are likely to occur. In most cases, the micro-cracks were generated in a cleaning area 1-2 mm from the weld metal toe to the base material side.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawback, and is intended to prevent a micro crack in a heat affected zone of a weld even when an aluminum material is an extruded material having a coarse surface recrystallization. An object of the present invention is to provide a method for welding the obtained aluminum material.

[0006]

Means for Solving the Problems For the above purpose, the present inventors have conducted intensive studies and as a result, when the cleaning area is widened in TIG welding or the like, the range of micro cracks in the heat affected zone is widened,
It has been found that by controlling the width of the cleaning area (hereinafter referred to as the cleaning width) within a certain range, it is possible to prevent minute cracks in the heat-affected zone, and to complete the present invention based on this finding.

That is, according to the present invention, referring to the reference numerals in the drawings, the present invention provides an aluminum alloy having a cleaning area (2) formed at the time of welding.
The method for welding a minium material (1), wherein the cleaning
To the toe (3a) of the welded metal part (3)
Welding cracks characterized by being restricted to within 1 mm from
The gist of the invention is an improved method of welding aluminum materials .

Note that (4) shown in FIG. 1 is an oxide film.

[0009] The cleaning action generally occurs in bar plus (base metal cathode) welding using argon as the shielding gas. The specific type of welding may be TIG or any other type as long as it produces such a cleaning action. Here, the cleaning width (W) corresponds to the welding metal part (3).
Is regulated within 1 mm from the toe (3a) for the following reasons. That is, it is presumed that the cracking of the heat-affected zone is caused by the stress generated due to the imbalance of the structure in the solidification process after welding the heat-affected zone and the welded metal portion. Thus, when the cleaning width (W) is large, the heat-affected zone is also wide, and the heat-affected zone is liable to cause minute cracks.
This is because when the cleaning width (W) is 1 mm or less, the heat-affected zone becomes narrower and micro cracks are suppressed. However, the case where the cleaning width is 0, that is, when there is no cleaning action, is not included in the scope of the present invention. This is because if there is no cleaning action, bubbles and foreign matter are mixed during welding, resulting in poor appearance. It is particularly preferable to regulate the cleaning width to 0.1 to 1 mm.

[0010] The cleaning width (W) is set to the welded metal part (3).
Although a specific method for controlling within 1 mm from the toe (3a) is not particularly limited, for example, the following method can be used.
That is, as the most preferable method, the EN ratio (Electrod) of the current applied between the electrode and the aluminum material (1) is determined.
e Negative ratio).
Here, the EN ratio is defined as 1 as shown in FIG. 2 when the electrode rod of a TIG welding machine or the like is set to the + side and the aluminum material (1) is set to the − side.
When a repetitive pulse current in which the aluminum rod is positive and the electrode rod is negative during the time T1 and the electrode rod is negative during the time T2 and the electrode rod is positive and the aluminum rod is negative during the time T2 is applied, the EN ratio =
A ratio represented by {T1 / (T1 + T2)} × 100 (%). Conventionally, the EN ratio is generally set to about 50%, but by setting the EN ratio to about 70 to 95%, the cleaning width (W) is restricted to within 3 mm from the weld metal toe (3a). Can be. If the EN ratio is less than 70%, the cleaning width may exceed 3 mm.
If it exceeds 5%, the cleaning width may become zero.
Therefore, when the EN ratio is within the range of about 70 to 95%,
EN ratio is set so that the width (W) is within 1mm
do it.

Although the cleaning width (W) varies depending on the shielding gas flow rate and the welding current, depending on the base material dimensions, the cleaning width (W) is regulated by regulating the shielding gas flow rate and the welding current within a certain range. It may be regulated within 1 mm . Specifically, the shielding gas flow rate is 3 to 1
It is good to set to about 0 l / min. If it is less than 3 l / min, the appearance of the weld may be poor, and if it exceeds 10 l / min, the cleaning width may exceed 3 mm.
The welding current may be set to about 50 to 150A. If it is less than 50A, there is a possibility that poor penetration of the welded portion may occur. If it exceeds 150A, the cleaning width may exceed 3 mm. Further, the control may be performed in accordance with the EN ratio, the shield gas flow rate, and the welding current.

[0012]

[Example] A5083P-O, 4.0t x 100w x 3
A groove was formed on the surface of the aluminum base material of 00 l (mm), and the groove was welded using an AC-TIG inverter control welding machine. Here, A518 is used as the filler material.
1.0 m from the weld metal toe by appropriately combining the welding conditions of EN ratio, Ar shield gas flow rate, and welding current as shown in Table 1 using 3BY; 2.4 φ (mm).
m, 1.5mm, 2.0mm, 3.0mm, 4.0mm
Various cleaning widths were formed.

[0013]

[Table 1]

Next, in order to examine the relationship between the cleaning width and the welding crack in the heat-affected zone, the J
Cracks were confirmed by a penetrant test specified in IS, and the length of the cracks was measured.

Then, for each cleaning width,
A value of (crack length / cleaning width) × 100% was calculated and both were shown in a graph, which was as shown in FIG.

From the above results, it can be seen that welding cracks in the heat-affected zone can be suppressed by regulating the cleaning width to within 1 mm from the weld metal toe.

Further, using the same aluminum base material, filler material, and welding machine as described above, the weld metal portion when the EN ratio is changed under the conditions of a welding current of 150 A and a shielding gas flow rate of 10 l / min. When the cleaning width from the toe was measured, it was as shown in the graph of FIG. From this graph, it is possible to restrict the cleaning width from the weld metal toe to 3 mm or less by setting the EN ratio to about 70% or more, and to set the EN ratio in a range exceeding 70%.
It is clear that the cleaning width can be regulated within 1 mm.
Call It is also understood that when the EN ratio exceeds 95%, the cleaning width rapidly approaches 0.

Also, using the same aluminum base material, filler material and welding machine, welding current: 150 A, EN ratio: 7
The cleaning width from the weld metal toe when the Ar shield gas flow rate was changed under the condition of 0% was as shown in the graph of FIG. From this graph, by setting the shielding gas flow rate to about 10 l / min or less, the cleaning width can be regulated within 3 mm , and the shielding gas flow rate can be reduced below 10 l / min.
By setting the rotation range, the cleaning width can be set to 1 mm or less.
It can be understood that it can be regulated within. When the flow rate of the shielding gas was less than 3 l / min, the appearance of the weld was poor.

Further, when the same aluminum base material, filler material and welding machine were used and the welding current was varied under the conditions of an EN ratio of 70% and a shielding gas flow rate of 10 l / min. When the cleaning width from the weld metal toe was measured, the result was as shown in FIG. From this graph, by setting the welding current to about 150A or less,
Again, it can be seen that the cleaning width can be regulated within 3 mm. Also, when the welding current was less than 50 A, poor penetration of the weld occurred.

[0020]

According to the present invention, since the cleaning width is limited to 1 mm or less from the weld metal toe in welding of an aluminum material having a cleaning action, the aluminum material has a large thickness of about 100 to 150 μm. Even in the case of extruded profiles having surface recrystallization and welding such profiles, it is possible to suppress weld cracks in the heat-affected zone, which has conventionally occurred, and to achieve a high-quality weld structure without weld cracks Things can be produced and provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of an aluminum material after welding.

FIG. 2 is a waveform diagram showing an example of a current applied between an electrode bar of a welding machine and an aluminum material, with the electrode bar being on the + side.

FIG. 3 is a graph showing a relationship between a cleaning width and a welding crack.

FIG. 4 is a graph showing a relationship between an EN ratio and a cleaning width.

FIG. 5 is a graph showing a relationship between a shield gas flow rate and a cleaning width.

FIG. 6 is a graph showing a relationship between a welding current and a cleaning width.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Aluminum material 3 ... Weld metal part 3a ... Weld metal part toe W ... Cleaning width

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-57-134268 (JP, A) JP-A-4-309468 (JP, A) JP-A-64-53773 (JP, A) JP-A-57-134268 195593 (JP, A) JP-A-64-22471 (JP, A) JP-A-3-81071 (JP, A) JP-A-2-97967 (JP, U) (58) Fields investigated (Int. ⁷ , DB name) B23K 9/23 B23K 31/00 B23K 103: 10

Claims (1)

(57) [Claims] 1. A method for welding an aluminum material (1) in which a cleaning area (2) is formed at the time of welding, wherein the width (W) of the cleaning area (2) is adjusted by a toe (3a) of a welded metal part (3). A method for welding aluminum material with improved welding cracks, characterized in that the welding is restricted to within 1 mm .