Stainless distortion

admin

Hi everyone,I'll be soon working on a stainless project at work, im the only one who can ''Tig'' in the shop but i don't have 20 years of experiences so i still have couples question before starting.I won't draw the shape of the pieces but i'll give youa good description, the material will be 304 stainless solid barsabout 3/4 X 1'', and to give you an idea of the joint, it will have the shapeof a hockey stick, the joint will be obviously in the angle where it bentand everything will be cleaned, buffed and pollished.I know by experience that stainless move a lot during welding (distortion)but im not really scared about working with distortion, i know im able to putmetal pieces back to the original shape, stainless distortion a lot but its alsostay soft for long time when its hot, and you can do whatever you want with hotmetal pieces.My questions is more about some extra tips to avoid distortion during welding becausethe pieces need to be really clean because they are for architectural construction, i don't wantto pry to pieces under my table and maybe make some deep marks on the stainless and make thepolisher work longer on those pieces, so what are my options ?Purging with air ? (never done that by myself, only seen other welders doing that)Welding the pieces directly in the jig and then cooled it with water and unclamp when its cold ?Thank You!Calculator > Bevel Square
Reply:Is it all solid bar or are there tubes you are welding the solid bar to? If there are tubes you may need to purge. To keep the stainless from moving so much after welding one of the main things I try to do is limit heat input. Read the puddle and get it moving, keep it satisfied with filler. Welding too cold and slow causes lots of problems with too much heat. Correct amps/travel speed/arc length/filler amount will all help with heat input, keeping the metal really clean can help a bit because it lets the puddle wet out better. I would tack/weld it in the jig then let it cool.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Thank you, its all solids bars!And sorry, im not really good in english as you can see with my sentences, what do you exactly mean by ''one of the main things I try to do is limit heat input'' just descrbide what you do with machine settings or whatever ? I have a question about purging, in the case that i don't have access to air compressor, can i use water ? juste spray water on my piece ?if water won't work the same as air purging i want to know before i try some stupid things !!Last edited by LayoutMan; 11-30-2013 at 09:34 PM.Calculator > Bevel Square
Reply:Limiting heat input is just keeping it from getting so hot, not only the whole part but the area near the weld. Use only the amperage you need to- Don't weld too cold causing you to weld slow and put lots of heat into the part, don't weld too hot and too slow either because of the same problem. You want enough amperage to get a puddle formed very quickly. After the puddle starts, add filler wire and watch it all fuse. Move along as fast as you are able to while making sure its all fused.Purging is where you fill the inside of tubes/pipes with shielding gas (Argon). Since you won't be welding any tubing you won't need to purge.A large cup or gas lens on your torch will help keep good colors on the steel, solid bar tends to discolor more because it holds heat a long time.Don't cool the piece down with water or air, cooling one side faster than the other will only cause it to distort worse.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Are these decorative or structural? If they are only decorative, you shouldn't need heavy welds. A small bevel and then fill should be more than enough. If the welds are structural, then you'll have to dump more heat into the pieces because I'm going to guess they will want heavier welds, if not full penetration welds.If that's the case you may need to weld and wait for the pieces to cool to limit heat. Stainless tends to want to pull a lot as it cools, so you probably need to keep alternating sides as you go to pull one weld against another working to keep things as straight as possible as you go..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:@Squirmypug  Thanks for the extra explanation, all clear now haha@ DSW  No its only architectural handrail legs, the reason why i want them all on the same perfect angle shape is because they will beinstalled before the top railling tubing (the legs have little saddle to screw the top rail) and i don't want the top rail follow the wrong shape of some legs that could be to much distort. (i don't know if you get what i mean haha)Calculator > Bevel Square
Reply:I just noticed that at my shop we have TIG filler rod 1/16 dia, and we have an old MIG roll of 0,35 stainless wire, So my question now is that could help me to have less distortion if i fill the bevel with smaller (like the 0,35 MIG wire) than the normal filler ?Last edited by LayoutMan; 12-02-2013 at 04:46 PM.
Reply:Originally Posted by LayoutManI just noticed that at my shop we have TIG filler rod 1/16 dia, and we have an old MIG roll of 0,35 stainless wire, So my question now is that could help my to have less distortion if i fill the bevel with smaller (like the 0,35 MIG wire) than the normal filler ?
Reply:Try backing the SS flange or bar you are welding the tubing too with a heavy/thick aluminum plate.  The aluminum will conduct some of the excess heat away from your weld area and prevent distortion.  You can either bolt or clamp the piece to be welded directly to the Aluminum plate.
Reply:Originally Posted by weldermikeThe whole time I was reading this I was thinking strategicly placed tacks to keep from pulling and yes small filler. I'm still having a hard time picturing the job in my head tho.
Reply:Using well designed solid sturdy jigs and hold downs should do the trick. Make sure your volume of filler and theheat input is equal for both sides as you complete.
Reply:When you first said "purge" I thought you might be thinking of hitting the part with a blast of compressed air after a short weld to cool the weld and part before continuing, not a bad plan. Another way to go is to preheat everything then weld, tough to do without an oven. A massive aluminum jig would help suck the heat out as you weld at first, but I have found jigs like that work just as good or better when they get hot and act more as a preheat than a chill block.SqWave 200Millermatic 190Airco 200 ACHypertherm PM45Boice-Crane Band SawVictor O/A