Stainless Steel Welding - Thickness vs. Bead Length

[mechead]

I am designing a stainless steel assembly which needs a 70 inch circumferential weld as well as a 50 inch long longitudinal weld to form parts of an APU pressure/containment shroud inside an aircraft. My welder says that the longer the bead length, the greater the thickness needs to be to avoid warpage. Stress and durability wise, I can get by with as little as .032 sheet.

Do guidelines exist for the thickness vs. bead length problem for thin sheet?

Thanks in advance.
Justin Young
youngj921@asme.org

 

[welding1]

I have seen some quite incredible distortion with stainless steel, even on thick sections. Unfortunately this material has high coefficient of expansion and is a poor conductor of heat, making very susceptible to distortion.

Use a low heat input welding process such as MIG(GMAW) dip transfer or better still laser if you can get access to one. Try and hold it shape during welding with some external bracing or stiffening. Which you could remove after welding, or leave in place. Try some test welds on different thickness.

There is some basic guidance on distortion at

http://www.twi.co.uk

http://www.gowelding.com

 

[mcprofusion]

To control distortion you can use water cool copper shoes.