JPS597493A - Aluminum alloy filler metal - Google Patents

Abstract

PURPOSE:To provide an Al alloy filler metal having excellent mechanical properties and corrosion resistance without any weld crack, by adding specific amts. of Mg, Zr, Mn, Ti, B and Fe to Al. CONSTITUTION:A filler metal having the compsn. added with 3.0-6.0wt% Mg, 0.15-1.0wt% Zr, 0.05-0.3wt% Mn, 0.01-0.3wt% Ti, 0.0001-0.01wt% B, and 0.05-0.5wt% Fe to Al is used as a filler metal to be used for welding Al alloy members. A weld zone having excellent mechanical properties and corrosion resistance is obtd. without any weld crack.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aluminum alloy filler metal having extremely low weld cracking susceptibility and excellent welding performance.

In recent years, lightweight structures have been desired for structural buildings.
Along with this, alloy materials for welded structures such as At-Mg alloys or At-Zn-Mg alloys have been widely used.

At-
Mg-Mn-Cr alloy e.g. 5183.5356°5
556 is used. These filler metals have good weldability, but have the disadvantage that weld cracks often occur depending on the structure of the welded object, welding conditions, etc., impairing joint strength and corrosion resistance. In particular, when At-Zn-Mg alloy materials are welded, Zn is mixed into the weld metal, making it easy for weld cracks to occur, especially at the weld end.

The present invention has been made as a result of extensive research aimed at improving these drawbacks, and has resulted in the discovery of an aluminum alloy filler material that does not cause weld cracking and has excellent mechanical properties and corrosion resistance. That is, the present invention uses Mg 3.0 to 6. Owtl, Z
rO, 15-1. Owtl, Mn 0.05-0.
3 wt4, Ti O, 01~0.3 wtl, B O
,0001~O,Ol wtl,FeO,05~0.
5 wtl and the remainder At.

In the present invention, by adding Mg to At, p At
Hardens the alloy and improves the strength of welded joints. Furthermore, by adding Zr, the grains of the pAt alloy are made finer and the susceptibility to weld cracking is reduced, the strength of the welded joint is further improved, and the susceptibility to stress corrosion cracking is reduced. Furthermore, by adding Mn, the strength of the welded joint is further improved and the stress corrosion cracking susceptibility is further reduced. Furthermore, by adding Ti and B, the crystal grains of the deposited metal are made even finer, and the weld cracking resistance is further improved.

Furthermore, the susceptibility to solubility cracking is reduced by adding Fe.

The reason why Mg is limited to 3 to 6 wt% in the present invention is that if it is less than 3 wt%, the strength of the welded joint will be insufficient and weld cracking will easily occur, and if it exceeds 6 wt%, workability will be poor. The toughness of the weld metal decreases. Also, the amount of Zr added is 0.15 to 1. The reason for limiting it to Owt% is
O,] If it is less than 5 wt%, the effect of reducing weld cracking susceptibility is weak; This is because when Owt exceeds 4, it is difficult to form a huge intermetallic compound and the toughness of the weld metal decreases. Also, the amount of Mn added is 0.0>~0.3 wt.
% is because less than 0.05 wt% has little effect on improving the strength of welded joints and reducing stress corrosion cracking susceptibility, and if it exceeds 0.3 wt4, the workability of the alloy is poor. be. Also, the amount of Ti added is 0.01~Q, 3w
The reason for limiting it to t% is 0. O] If the content is less than 4 wt%, the effect of making the crystal grains of the deposited metal finer and reducing the susceptibility to weld cracking will be weak, and if it exceeds 0.3 wt%, the toughness of the weld metal will decrease. Also, the amount of B added is 0.00
01~0.01 The reason for limiting it to wt4 is 0,000
] When wt is less than 1, the effect of refining the crystal grains of the weld metal and reducing weld cracking susceptibility is weak < , 0.0 ]
If it exceeds wt4, the fluidity of the molten metal to be welded will be impaired. The reason why the amount of Fe added is limited to 0.05 to 0.5 wt4 is that less than 0.05 wt4 is less effective in reducing weld cracking susceptibility, while more than 0.5 wt4 reduces the toughness of the weld metal. This is because it decreases.

Although Cr is added as an essential element to conventional Ag-Mg alloy filler metals, the present invention adds a large amount of Zr to provide sufficient strength properties to the welded metal part without adding Cr. It can be granted.

Next, examples of the present invention will be described.

A small diameter 9 alloy ingot having the composition shown in Table 1 is
After extrusion into rods with a diameter of 1.6 am, annealing and wire drawing were repeated several times to obtain a filler metal of the present invention, a comparative filler metal, and a conventional A3356 filler metal with a diameter of 1.6 am.

Using these filler metals, weld base metals (A7
JlJclI P-T4 material) was welded.

Table 2 (wt section) A weld cracking test and a tensile test were conducted on the welded parts thus obtained. The results are shown in Table 3.

The weld cracking test was carried out using a weld with a depth of 7 mm, a 90° 7-shaped groove 2, a thickness of 15 mm, a width of 200 mm, and a length of 250 mm as shown in the drawing.
Using o+ welding base metal 1, bead-on-rate welding 3 the groove part using the filler metal shown in Table 1 under the conditions shown below,
The crackability was evaluated by measuring the total length of the crack 5 of the crater 4 that occurred in the groove.

Welding method Fully automatic MIG Down position welding conditions Current 280A Voltage 26V Speed 45mm/ml Ar flow rate 28A/min The cracking rate is the length of cracking that occurs when welding using conventional filler metal (Y9). It is converted as 100.

In addition, the tensile test was conducted using a filler metal with a diameter of 1.6 tran with the same composition shown in Table 1 as that used in the weld cracking test, and a weld base material with a thickness of 5 m with the chemical composition shown in Table 2. were butt welded under the conditions shown below, left at room temperature for one month after welding, and then the excess of the welded joint was removed.

Welding method Fully automatic MIG downward position welding conditions Current: 240A Voltage: 22V Speed: 60 pieces/ml n Ar flow rate: 25 A/ml n As is clear from Table 3, welding was carried out using the filler metal of the present invention (Al-44). The welding part is a conventional filler metal (49-A10)
Weld cracks are less likely to occur and it has superior tensile strength and yield strength compared to welded parts welded using . When using a comparative filler metal (flat 5), which has a lower Zr content than the filler metal of the present invention, there was almost no improvement in weld cracking resistance compared to the conventional filler metal, and the tensile strength and yield strength were lower. is not improved either. A sample using a comparative filler metal (, tK 6 ) with a high Zr content showed the same weld cracking resistance as a sample using the filler metal of the present invention, but was slightly inferior in elongation. Those using a comparative filler metal (A7) with a lower Fe content than the filler metal of the present invention and those using a comparative filler metal (A8) with a higher Fe content than the filler metal of the present invention. Both are inferior to those using the filler metal of the present invention in terms of weld cracking resistance and elongation.

As detailed above, the filler metal of the present invention is extremely useful industrially in this field, as it is less likely to cause weld cracking, has excellent mechanical performance, and can reduce the weight of structures to be welded.

[Brief explanation of the drawing]

The drawing is a schematic explanatory diagram for testing the weld cracking property of the aluminum alloy filler metal of the present invention. J...Welding base material, 2...Groove, 3...Bead, 4...
...Crater, 5...Crack.

Claims (1)

[Claims] Mg 3.0-6. OwtqblZr O, 15-1.
0 wt%, Mn 0.05-0.3 wt4, TiO
,01~0.3 wtl,Bo,0001~0.01
An aluminum alloy filler metal comprising: wt, F.0.05 to 0.5 wt, and the balance At.