Testing a weld

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So how do I know if my stick welds are any good?I don't do things that people tow, walk over or hang from - yet - but I still want to know if they're okay.I could cut them in half to check, but then I'd have to weld them together again and how would I know that weld is any good?Grinding will expose a bad weld, but with some welds it's hard to get the grinder in there.Scott
Reply:I would have to say if you know someone with some more experience you can ask them or post a pic for opinions on here.  Sometimes i use a huge hammer or press and destructive test is to see what part of it breaks.  Downside is it is destroyed .  Theres places you can send it to have it tested to.
Reply:I might do some testing myself on some scrap - weld some things together, hit them with a hammer and then cut them with the chop saw just for curiousity.Scott
Reply:The main thing is that you want the piece to pretty much bend backwards against itself.  My old highschool used to have a bearing press (at least, that's what it looked like) with a U-shaped die and a pointy thingie that was used to do our testing.  They would slap 20 tons of force on the weld and if it didnt break or crack during the bend, they would flip it over and do it the other direction.  That was almost as fun as the welding.  I have to say, weld defects show up pretty quick in those conditions.  We had 55-gallon drums full of these bend tests.Last edited by smithboy; 12-15-2005 at 12:04 AM.Smithboy...if it ain't broke, you ain't tryin'.
Reply:scott, try this....do a test coupon.   After you weld it.   Grind it down smooth.  No weld left.  but you should do something that alllows you to identify where the weld is...example would be weld two pieces the same length together...ok...when you grind...make sure your grind marks are perpindicular tothe weld also.  Then stick it in the vice....Beat the living heck out of it.  If you can bend it 90degrees over,  I say you got a good weld...prefered methos is with a guided bender.   Basically its a jig withh a bottle jack thatallows you to bend the part in a very uniform manner..but beating on it will do a lot to gain similar results.  If it does break, look at where it broke and how..look for inclusions, for lack of fusion ect.Also, before you start to grind.  Clean with a wire brush.  Look for things like undercut...some call it fingernailing...this is bad.  Look for cold lap as well.  As mentioned above you can post pictures..but thre is only a coupke things the pictures will tell us...its better if were right thereIF it Catches...Let it Burn
Reply:Smithboy, I'd hate to subject some of my welds to that sort of test.TX I'll give that a go.What's 'undercut' and 'cold lap'?As for being 'right here', it's a fair way.
Reply:Another method might be to do one side (fillet) of a T, put it in a vise and bend it over as close to the weld as possible. Do one on thinner like 1/8th and a thicker one. Maybe even subject it to the BFH test. Do what ya gotta do. Many times we go into these tests with a certain amount of reserve like we are testing ourselves and don't give it everything we've got. The real point is that it isn't always a test but more that of analyzing the weld process and its affects on the material. You want this weld to come apart if at all possible or turn the metal to pulp trying. Your goal is to see what breaks, where it breaks, why it broke and if there was something we could have done better. Learn from the whole ordeal. See where cracks start, see what broken weld looks like with different fillers, see where the metal is most likely to bend due to the welding process. You really do learn a lot from these exercises. Can also be a real confidence builder.
Reply:Scott,  ok you asked about undercut...undercut is easier to describe.   When you look under your car at the frame,  go look and at the toe...edges of the weld, look for what looks like a little groove running the length of the weld.  Can you find one or more?  Often we find this on the fram of our cars.  Its infortuante but true.  Anyway, if its not there count yourself lucky.  This groove is the undercut.  To understand the problems with undercut think of a piece of glass.  Ever worked with glass?  Know anything about it?  Well to cut glass you dont cut it with a knife, or blade all the way through.  No you score a line wher eyou want to cut.  The apply pressue from the oppposite you scored.  It will shear perfectly.  Well this also happens with metal.  Do ya get my drift.  Ok, so cold lap.   When metal fuses properly it flows gently ino the base metal from the bead.  Whereas is tehre is a real obvious, I guess its kinda almost like seeing a gentle slope vs a cliff.  Not that extereme but I hope you can see my point.  Again you can prolly look at yuour car to see what im saying.  But better yet go out to your welder machine and run a bead with the heat how you like it.  Then one with the amps way low.  Look at the bead profile how it blends.  Does this help?    If its not flowing its not really fusing properly.   anyway hope this helpsIF it Catches...Let it Burn
Reply:Yep, that makes sense. Thanks guys.