TIG Welding Heat Transfer Question
TIG Welding Heat Transfer Question
(OP)
I have an application where I have a 3/8" thick plate, mild carbon steel. One side is painted with an industrial enamel rated around 250 deg F, the other is unpainted. On the unpainted side I am performing some stitch welds running about 200A. Using 1/8 Tungsten, and 3/32 filler. The bead size is between 1/8-3/8" and about 2" long. I am having trouble because the paint on the opposite side is bubbling and distorting from the heat, causing unneeded rework of the paint. I need a method to capture the heat and prevent the paint on the other side from getting ruined. The opposing side must be painted before welding due to our process and limited painting requirements post weld.
Thanks so much for any and all advice.
Thanks so much for any and all advice.





RE: TIG Welding Heat Transfer Question
It may be possible to use wet cloths on the back side (with the enamel) to act as a heat sink while you make your welds.
RE: TIG Welding Heat Transfer Question
RE: TIG Welding Heat Transfer Question
RE: TIG Welding Heat Transfer Question
Something doesn't seem right.
You say bead size is between 1/8 and 3/8" - that is quite a difference.
What is the filet size called for on the drawing ?
200 amps seems pretty hot for GTAW - are you doing theses fillets in one run ?
If so try doing two or three small beads instead of one large - see how that goes.
Hope that helps,
Cheers,
DD
RE: TIG Welding Heat Transfer Question
Mike Halloran
Pembroke Pines, FL, USA
RE: TIG Welding Heat Transfer Question
RE: TIG Welding Heat Transfer Question
When welding carbon steel, rapid cooling can result in welds that are not as ductile as they would be if they were allowed to cool slowly. There are application where there is little alternative, such as repairing a leaking hull in a ship while underway. Generally, slow cooling is best when welding carbon and low alloy steels.
You may save the paint, but at a loss of ductility and an increased opportunity to experience hard, brittle welds, delayed cold cracking, and porosity.
Best regards - Al
RE: TIG Welding Heat Transfer Question
In my hobby welding experience workpieces/weldments simply don't get nearly as hot as when TIG welding.
RE: TIG Welding Heat Transfer Question
Best regards - Al
RE: TIG Welding Heat Transfer Question
In my strictly hobby welding experience it takes me a while to get a puddle going using TIG or oxyacetylene, and while welding I need to be mindful about resting my hands or arms on the ever hotter workpiece, or when picking it up when finished.
Zapping the OP's 2 inch long fillet stitches wouldn't take long at all with SMAW.
I'm not sure about the suitability of any (DCEP) SMAW electrodes for Marcus388's application but they offer some advantages on thinner materials due flipping the 70/30 heat relationship of the DCEN electrodes
RE: TIG Welding Heat Transfer Question