Aluminum MIG Welding - failed PQR
Hani Al Masry
and inclusions but even 2nd test was failed (attached photos for your reference)
|
Weld Layer |
WELDING PROCESS |
WELDING POSITION / DIRECTION |
ELECTRODE(S) |
GAS SHIELD |
GAS FLOW RATE lit/min. |
AMPS |
VOLTS |
WELDING SPEED mm./min. |
FLUX |
WFS M/Min. |
Mode of Metal transfer for MAW |
||
|
SIZE mm |
TRADE NAME |
POLARITY |
|||||||||||
|
1 |
GMAW |
3G |
1.2 |
AUTO ROD 5356 |
DCEP |
ARGON 99.99% |
15-25 |
120-180 |
18-26 |
12-20 |
NA |
8.5 |
Pulse transfer |
|
2 |
GMAW |
3G |
1.2 |
AUTO ROD 5356 |
DCEP |
ARGON 99.99% |
15-25 |
120-180 |
18-26 |
120 - 140 |
NA |
8.5 |
Pulse transfer |
|
Back weld |
GMAW |
3G |
1.2 |
AUTO ROD 5356 |
DCEP |
ARGON 99.99% |
15-25 |
120-180 |
18-26 |
100 - 110 |
NA |
8.5 |
Pulse transfer |
Chintan
c sridhar
The main cause for porosity in aluminum is hydrogen, which has very
high solubility in molten aluminum but very low solubility in solid. Hydrogen gas is
therefore evolved as the weld pool solidifies. If the cooling rate is
too high, the gas remains in the metal in the form of porosity. Thus,
any compound containing hydrogen and contaminating the filler wire or
work surface can cause porosity.
Oil, moisture or other contaminants may be present on the filler wire. In addition, the oxide layer of aluminum tends to get hydrated and improper cleaning of the oxide layer immediately preceding welding could be a cause for porosity. Ensuring that the plate is clean before welding and switching to clean, high quality electrodes will reduce the likelihood of forming porosity.
The amount of porosity depends on how fast the weld pool solidifies. Increasing the welding current and/or decreasing the travel speed will increase the heat input, and help retard the cooling rate allowing gases to escape from the weld pool and thereby reducing the risk of porosity.
will pass through.
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Adriaan Stoltz
Was the correct “former” diameter used for the bend tests? Also, where did the tensiles break?
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Ramin Kondori
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George Dilintas
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Hani Al Masry
Cleaning prior to welding
To achieve low porosity levels for x-ray quality welds, it is important to understand the methods available for the effective removal of hydrocarbons and moisture from the weld area, and to incorporate the appropriate methods into the welding procedure. If these contaminants are present in the weld area during welding, they will produce hydrogen and significantly contribute to porosity problems.
When designing welding procedures intended to produce low levels of porosity, it is important to incorporate degreasing and oxide removal. Typically, you can achieve this through a combination of chemical cleaning and/or the use of solvents to remove hydrocarbons followed by stainless steel wire brushing to remove contaminated aluminum oxide.