ALUMINIUM 6082 -T6

Vishwas Keskar Welding Manager WELDING

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Aug 22, 2023, 12:00:42 AM8/22/23

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Dear Experts

ALUMINIUM 6082 -T6 - 32mm , 20 mm , 16 mm plates

32mm ,-32mm- Butt joint

20 mm-20 mm-Butt joint

16 mm - 16 mm -Butt joint

Above plates are jointed through butt joints .

Welding Process - GMAW

Gas - Argon

Filler wire - ER4043

Due to job part length , there is distortion at the vicinity of butt welds. So Cold straightening operation was carried out on Press. The weld/HAZ cracking is observed immediately the press load is commenced

Pl. suggest suitable action for Welding/cold straightening

Thanks

Vishwas - IWE

sridhar cn

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Aug 22, 2023, 11:10:59 PM8/22/23

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Aluminium Alloy 6082 has very good weldability, but strength is lowered in the weld zone. When welded to itself, alloy 4043 wire is

recommended. If welding Aluminium alloy 6082 to 7005, alloy 5356 is used.

You have not mentioned the parameters selected, tests conducted after welding, or approval standards followed (AWS D 1.2 /

ISO 15614-2 etc.). Whether NDT (Radiography and visual) or DT (mechanical tests) were carried out before distortion correction.

Pores may create under-bead cracks and potential causes include:

Presence of molecular hydrogen.
hard microstructure.
High weld residual stresses.
Fast cooling rate.
Not applying preheat or insufficient preheating for welding.

· Welding without cleaning moisture, etc.

During the welding of the Aluminium alloy, hydrogen can cause pores, because its solubility in liquid Aluminium is much higher than

that in solid Aluminium. Hydrogen is restrained in the molten pool with the advance of the solid-liquid interface. This could be avoided by

pre-heating the job (due to its high thickness) and causing slow cooling.

Under the stress of external loading, a large number of hydrogen atoms may gather at the grain boundary resulting in stress concentration

resulting in crack initiation; Under the action of external or tensile stress and a larger stress intensity factor, the pores, generated by

hydrogen atom absorption initiates cracks and shows different propagation modes.

Further, due to the higher coefficient of thermal expansion apart from joint pre-heating, avoid continuous welding. Follow sequence welding

(placing welded metal at different points and joining them together) method, back-step method (to avoid heat concentration), job pre-setting

(before tack welding) by 5 to 7 deg. etc. to control the distortion.

C Sridhar.

·

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