Ok this is a bit of a newb question. When I weld 1/4" and up steel as it cools it sometimes cracks along the weld. What causes this and how can I prevent it? TIG welding if that makes a difference.
Thanks in advance.
weldmaster36602
- weldmaster36602
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Joined:Sat Sep 04, 2010 4:29 pm
what are u welding with mig tig r stick
is this just mild steel (hot/cold rolled plate) or something more exotic? what filler (tig, so I'm assuming ER70S2). how hot are you welding? are you welding putt joints, lap joints, tee joints, lapped or open corner?
my first guess is you need to clean your steel better. that's been the only source of any problems for welding on plain old carbon steel for me. dirty steel=crappy weld. also, you might check out your gas coverage, tungsten stickout, ect. are you getting any brown 'dust' on the weld, any of it looking that 'burnt grey' color? probably not enough shielding if that's the case.
following jody's rule of thumb, you should be welding at around 250A for a single-pass weld (1A per .001"). most people don't have 250A to play with, so you need to plan on doing front and backside to get complete penetration. for a butt weld, bevel the crap out of both sides, weld the non-visible side first, straighten the piece back out, then weld the top. corners you're going to want to do an open corner, you can get away with 1 pass on the outside even with only about 150A, but you'll need to put a cap pass over it if you want the corner to be square. I'd recommend against laps unless you really have to as you'll have to move very slowly to heat your base metal up. I wouldn't bevel the lap in this situation as you'll just end up melting the edge of the top plate trying to melt into the base plate. if you do have to lap, DEFINITELY weld both sides of the lap on something this thick. welding one side of the lap is just making a hinge. with a tee joint, bevel the bottom of the vertical piece, but you're going to have a similar problem as the lap joint burning into the full-thickness base plate. I'd probably put some heavy tacks or short stitches on one side, weld the other side pretty hot, mostly on the base, then go back and weld the other side.
working around limited machine capacity isn't a whole lot of fun, but it's necessary most of the time.
some other things to consider:
it could be a bad bottle of gas
it could be dirty filler (are you using a brand name? even the cheaper known brands are better than stuff from harbor freight).
it could be your tungsten (either it's contaminated (same thing as filler) or you picked up some crap from a weld. I like 1.5% lanth. jody says 2% holds up better, but I haven't burnt through this box yet, so I haven't tried it)
you could be getting the piece way to hot while welding. that happens when you don't have enough amperage. it takes forever to weld the thing and you heat it up a ton and it acts funny when it cools off. my guess is that it's probably this, now that I think about it.
anyway, more info would help, but hopefully you've figured it out already.
my first guess is you need to clean your steel better. that's been the only source of any problems for welding on plain old carbon steel for me. dirty steel=crappy weld. also, you might check out your gas coverage, tungsten stickout, ect. are you getting any brown 'dust' on the weld, any of it looking that 'burnt grey' color? probably not enough shielding if that's the case.
following jody's rule of thumb, you should be welding at around 250A for a single-pass weld (1A per .001"). most people don't have 250A to play with, so you need to plan on doing front and backside to get complete penetration. for a butt weld, bevel the crap out of both sides, weld the non-visible side first, straighten the piece back out, then weld the top. corners you're going to want to do an open corner, you can get away with 1 pass on the outside even with only about 150A, but you'll need to put a cap pass over it if you want the corner to be square. I'd recommend against laps unless you really have to as you'll have to move very slowly to heat your base metal up. I wouldn't bevel the lap in this situation as you'll just end up melting the edge of the top plate trying to melt into the base plate. if you do have to lap, DEFINITELY weld both sides of the lap on something this thick. welding one side of the lap is just making a hinge. with a tee joint, bevel the bottom of the vertical piece, but you're going to have a similar problem as the lap joint burning into the full-thickness base plate. I'd probably put some heavy tacks or short stitches on one side, weld the other side pretty hot, mostly on the base, then go back and weld the other side.
working around limited machine capacity isn't a whole lot of fun, but it's necessary most of the time.
some other things to consider:
it could be a bad bottle of gas
it could be dirty filler (are you using a brand name? even the cheaper known brands are better than stuff from harbor freight).
it could be your tungsten (either it's contaminated (same thing as filler) or you picked up some crap from a weld. I like 1.5% lanth. jody says 2% holds up better, but I haven't burnt through this box yet, so I haven't tried it)
you could be getting the piece way to hot while welding. that happens when you don't have enough amperage. it takes forever to weld the thing and you heat it up a ton and it acts funny when it cools off. my guess is that it's probably this, now that I think about it.
anyway, more info would help, but hopefully you've figured it out already.