Butt welding 60mm thick Aluminium EN AW 6082 T6 Plates

By Navdeep Date 02-13-2021 13:01

Hello everyone,

I am new to this forum.
We have a requirement wherein we need to butt weld two 60mm thick Aluminium plates (Material: EN AW 6082 T6) of size 850 x 1850 mm along the length. The joint has to have good strength (closer to the parent metal) and provide pressure sealing as well.

We have drafted the following welding process.
Joint type: double Vee, 2mm root gap and root face
Process: GMAW
MIG Wire: OK Autrod 5356, Yield: 120 MPa, Tensile Strength: 265 MPa, Make: ESAB
Pre-heating: None
Welding Position: 3G Uphill
Pre-cleaning: Sand paper
Interpass cleaning: SS Wire brush
NDT: Radiographic Test

Can you suggest if the aforementioned approach is correct?

Thank you in advance.

By 803056

Date 02-13-2021 22:06 Edited 02-13-2021 22:16

It is a start, but there is considerably more information that should be included in a formal written welding procedure specification.

I would so reconsider the presence of a root opening with the assumption the second side will be back gouged before welding the second side. More often than not, carbide rotary files are used to perform the back gouge. The root side of the weld will more than likely be heavily oxidized. Aluminum oxide is very hard and for that reason is used as the abrasive medium for grinding and sanding disks. That same hard oxide will play havoc with the cutting tools used to perform the back gouging operation.

A tight root condition will minimize the problem with the formation of aluminum oxide on the root surface.

Be aware that any of the 6XXX series aluminum alloys are overaged in the heat affected zone when welded regardless of the filler metal used. Designers should recognize the yield strength and tensile strength is adversely affected. One should anticipate the mechanical properties are going to be reduced on the order of 40% to 50%. The WPS should be qualified by testing to establish the mechanical properties. Interpass temperature should be closely controlled to minimize the adverse affects of overaging the alloy.

Just a few thoughts.

Good luck - Al