Steve and Denise
LIFE MEMBER
That’s just what I was thinking but in less words??You and I could have an excellent evening's discussion over a pint and I would relish listening to another welders take on their experience.
Now M.I.G welding when welding thin plate as any method should be done in a stitch style, because the parent metals are thin you would have to weld at a greater pass speed than welding a thicker profile.
Using a stitch method controls the heat input, you don't want weld deposit build up thus evading the need to grind back, using T.I.G is just another heating medium, now welding without a filler rod takes you into the realm of not having any gaps in the fillet or butt welds, this in itself creates the problem of joint creep were the joint closes over itself thus creating a rippling distortion.
Mild steel melts at between 1380'c to 1550'c depending on it's carbon content, obviously the more carbon the more brittle the weld will be, now using M.I.G for thin sheet you would just stitch using a spot weld technique thus avoiding too much weld build up avoiding the need to grind back.
Now using T.I.G for this, first you strike the arc, a T.I.G arc has a soft start builds to the intensity to melt the parent metal, excellent off we go but as in any situation without using a filler rod the weld will only be both joint edges melting together leaving a concave appearance with very little weld penetration, which can only promote weld cracking, so why not use a filler rod to mask the heat, after all you need the initial setting to melt the parent metals.
Of course the choice of inert gas will affect the weld temp and weld appearance.
As for my welding experience, I was Lloyds tested ASME 9 coded, Stamp Number 777.
Still have my tools and stamps.
I served my time as a boilermaker in the Petro Chemical Industry, welding most of the exotic metals, Inconel, Monel, Hastelloy, Stainless steel, Copper, Bronze, Cast Iron, Mild Steel etc etc, plus Aluminum and it's many Alloys.
Oil and Gas pipelines sunk to the floor of the ocean and pipelines across the Russian Tundra, I don't proclaim any welding snobbery if there is such a thing, bloody hell you spend your working life with your head in a bucket but I have spent many a night stove welding root welds on a 48" pipeline with fleetwelds, welding up cracks in Cast Iron Compressor engine blocks and for a party trick using a gas torch to do a butt weld on the silver paper from an old cigarette packet, won a few pints doing that trick I can tell you.