s/steel welding 3

[stevehart]

i've cut a s/steel benchtop (70cm wide) about 1mm thick to reduce its length and am trying to tig- butt weld it back together again. i've clamped the two pieces to a backing piece of steel 50mm wide x 5mm thick x 70cm long to try & line up the surfaces and reduce distortion. it has been tack welded every 5-10mm and it lines up well, but once i try to weld a continuous line major distortion comes into play predominately down wards. i've tried using lower amps, but means i have to stay in the one area longer, i've tried using higher amps can move quicker but also too much heat concentrated in one area, tried welding for a limited amount of time say 5 seconds which covers about 3cm of weld doesn't give me a consistant weld. how do I overcome or at least limit the distortion problem? thanks.

 

[EdStainless]

Skip weld, I would start in the center and work outwards (100mm in the middle, half way toward each edge another 100mm, then back on each side the middle, and so on).

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[strokersix]

Sometimes it helps to leave a slight gap. As you weld, the shrinkage will close the gap instead of buckling. You also might try making your tacks slightly thicker than the base material, then hammering them on-dolly to stretch and maintain the slight gap mentioned above.