I need help with 400-series stainless for a welding test

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Tomorrow I have a welding test with a potential employer. They use thin (16- to 22-gauge) stainless in 430 and 444. The test consists of two welds: a fusion lap joint, and an uphill T-joint with 0.035 filler. This morning I bought the thinnest stainless I could find locally, which is 20-gauge 304. I'm having a very hard time preventing carbide precipitation on the back side of the T-joint. Can anyone tell me if 430 and 444 are subject to sugaring? If they are, I'm gonna bomb this test in a big way.-Chris
Reply:All stainless steel grades are subjected to carbide precipitation and sugaring during arc welding.  Your parameters suggest you will be TIG welding a "1F" lap joint autogeneously and a fillet joint in 3F position. Check?  Grade 430 SS is a ferritic grade and usually requires pre-heating (300-400deg F) prior to burn-in.  Recommend you apply copper backing bars (~ 1/4" thick x 2" x 6", say) with mini c-clamps to the lap and fillet joints during initial tacks and for the single pass welds.Never welded any 430, but used the above Cu backer protocol for an AWS D17.1 test with 10ga 304SS and it worked perfectly.  You should also train on the SS grade/thickness you will be tested on to minimize any "surprises".Last edited by ManoKai; 07-20-2015 at 02:50 PM."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:Thank you for the reply. Can you explain how preheating will help when the material is only 0.025" thick?You are correct about the positions. I have my own copper backer, and using it was the only way I could control distortion in the 1F lap. I'd have bought 24 gauge 400-series, but no one stocks anything that thin locally, though they were all willing to order it. I was called yesterday for a test tomorrow, so ordering the material wasn't feasible.  I'm using the closest facsimile I could get my hands on.-Chris
Reply:PreHeating is usually specified for 430 sections with thicknesses above 1/8".  You are probably correct in your assumption that preheat for the 16ga and 20ga would not be required.  Will you have a WPS to follow for your test?  Have you asked the prospective employer for any insight into the test parameters and backimg requirements?For your lap joint, you may be able to insert a section of .035" filler rod UNDERNEATH the joint & clamp the assembly prior to welding.  Essentially, induce a pre-bend along the weld axis of the joint.  The resultant weld would then equalize/neutralize the bend and you should have a flat lap joint AFTER removing the clamps.Last edited by ManoKai; 07-20-2015 at 04:34 PM."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:What product does this company manufacture? It sounds interesting.Rich
Reply:The test ended up being no-filler outside corner joints on both 0.025 and 0.035 thicknesses. The biggest pain was the uphill T-joint with no filler. That's basically dragging the puddle from one surface to the other, then maintaining the arc and torch angle to drag the puddle up the joint and make a seam. Originally Posted by steelsurgeonWhat product does this company manufacture? It sounds interesting.Rich
Reply:Sweet! How did the test go?Dynasty 200DX   (2014)Millermatic 211 (2015)Optrel 864   (2014)Smith Medium duty MBA 30510 (Xmas 2014)Tennsmith 16ga 4ft finger brake (2015)Trailblazer 325 EFI and excel Thermal dynamics Cutmaster 82Miller maxtron 450
Reply:fitting and welding that stuff would make pretty much anything else look EASY!! i have done a bit of 304 round duct fab, but usually 16ga plus, and i thought that was a pain!!bosses stuff:trailblazer 325maxstar 200my stuff:sa 200fronius transpocket 180100 amp Lincoln w/f97 f350 DITKevin
Reply:Originally Posted by 92dlxmanfitting and welding that stuff would make pretty much anything else look EASY!! i have done a bit of 304 round duct fab, but usually 16ga plus, and i thought that was a pain!!