tig 18 ga. stainless

Date 07-31-2004 19:42

Just wondering if anyone could give me some tips on welding 18 gauge stainless. We have a job coming up that is basicly fusing the corners up on some pans. They don't want to grind anything, so they need to look nice. We are going to be using .040 2% thoraid tungsten and argon for shielding gas. We won't be purging the back side. I have always had difficulty welding thin stainless. I always have problems with burn through and warpage. The material doesn't seem to wet out until I get very close with the tungsten and a lot of times I end up contaminating the tungsten. Any tips?? I plan on practicing on my machine at home before the job comes through the shop. Any advice would be great!! Thanks!

By Lawrence (*****)

Date 07-31-2004 20:01

Your 0.040 tungstens are ok but so are 0.063.

Heat sinks, tight fitups and ergonomic part positioning are going to be the most important considerations for that job.

Assuming adequate joint cleaning.

A good square copper block clamped inside the corner will prevent burn through (tho you will need to increase amps slightly). The fitup between the chill block and the sheet metal must be tight tight tight, this way you won't have to go up and down on the foot pedal as contact with the chill block changes. The tight fitup will also prevent unpurged melt thru on the back side of the weld (sugaring).

Find a way to get yourself comfortable and that will allow you to make your full weld motion from start to finish without changing your torch angle, burning your hand or becoming overly fatuiged.

With the chill blocks and the extra steady hand I bet you find the job pretty easy.

By jdove55 (*)

Date 08-11-2004 00:19

Thanks for the advice. We welded some sample pieces today. It worked really well with the chill block behind. The samples were simple corner joints, but I guess the parts are going to be different. The corners won't be straight down, they will have a couple bends in them. Hopefully we can figure out a way to make a chill block to fit behind the joint since the fitup of the parts is not the best. I tried some samples without a chill block and it was tough. I had a couple turn out, but didn't have nearly as much color as with the chill block behind. The samples were thinner than the parts so it should be easier welding the parts. Is it possible to weld thin stainless without a chill block and without pulse arc??? I took a test at a company a while back on 18 gauge. It was a box with three sides open and they wanted the outside and inside corners welded. It didn't turn out too good. How do you weld this test without chill blocks?? How do you weld the inside without getting sugaring on the outside??? Clamp a piece of angle on the outside??? I would like to get good at welding thinner material. Thanks again for the advice.

By weldemup Date 08-12-2004 11:49

I like to use square aluminum tube for a back up in this situation. Its light and fairly cheap and makes a good heat sink. Also the corners are square so you can get a good tight fit in the corner. The tubing also works as an aid for fitup as it is easy to get a clamp on. If you have pulse on your tig machine use it and no filler metal. Fit up is very important on material of this gauge. When using copper as a chill bar on stainless you must be careful not to melt into the copper and cause admixture with the stainless, this will cause hot cracking. You can backpurge light gauge stainless by forming an aluminum foil chamber on the back side and purging it with argon.

Good luck