GMAW versus GTAW for thin SS sheet welding

[Fizza453]

What makes GMAW a low heat welding process? as compared to other welding processes?
We have to make but welds in 1.5 mm thick stainless steel (SA 240 TP304) with GTAW but our client is in the favor of GMAW by arguing that GMAW is a low heat process and better for thin sheet welding if compared with GTAW.

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

 

[stanweld]

GMAW with pulsed and short circuiting transfer offer the lowest heat input parameters (low Volts & Amps with small wire diameters and fast travel speeds). Plasma arc systems are ideal for stainless steel sheet welding where filler metal additions are not required.

 

[Fizza453]

Stanweld,

We have not available PAW with us.
GTAW or GMAW, which one is better for thin SS sheet welding (with the addition of filler metal)?

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

 

[stanweld]

Assuming that you are manually welding, use GMAW with the previously stated transfer modes.

 

[Kiwi2671]

Nasir,
Only my personal opinion but pulsed GTAW would be the best option.
Spot welding I would go with GMAW but welding seams on 1.5 mm would go with GTAW.
Stanweld may have experience with GMAW on very thin material but I have never had the same exposure to the newer transfer modes so cannot comment.
I have welded hundreds and hundreds of 1.6 mm WT 304 / 316 pipe welds with GTAW during my career so may be biased,
Regards,
Kiwi

 

[Mr168]

For a balance of speed and distortion control, I'd be looking heavily at a pulsed GMAW or STT process on sheet that thin.

 

[EuroWeld]

Knowing that GMAW-(P) gives a lower heat imput because higher travel speed I would weld this by GTAW-Pulsed or indeed with STT. When we encounter such situations we always make some test welds. Than you know what is the best option for the job. For GTAW the heat is also depending on the amount of used consumable.

 

[WBH]

Fizza

You could calculate the heat input for each method used. However weld quality should be considered.

personally GTAW would be preferred, this would require small diameter tungsten and rods. The amount of metal deposited is very controlled by the welder. For example rod can be feed at a steady rate or slowly dipped. Slow dipping allows for better control of the filler metal and heat input. Most common cause of high heat input with GTAW is slow travel speed and carrying a large amount of filler metal.

I would caution that the lower heat input obtained with GMAW by either a fast travel speed or low volt/amp combination can cause lack of fusion or cold lap even in thin materials.