Aerospace tig welding tests almost always involve a fixture like the one shown in this video. Little details like how you place the chill bars can make a big difference.
Even though it would be rare to weld plain 304 stainless for aerospace, the tips still apply.
Typical test material for the stainless group would be 15-7 or 17-7 stainless steel which is more difficult.
Fabricating a stainless steel part and talking about maintaining the corrosion resistance of stainless steel. Outside Corner joints using Aluminum angle backing
