View Full Version : Testing weld Strength
02-14-2005, 03:32 PM
Is there a good way to test my weld's strength? I just wanted to put it to the test to see if my welds are good enough for some friends stuff, or even my own safety.
Generally the answer to that question is: If you don't know if it is strong enough to be safe...it isn't. It takes a little bit of time under the hood to know what you are looking for to read the heat and penetration in the weld. Post some pics and you will probably get more feedback than you would ever want. Some more info on what you are welding and what with would help too.
02-16-2005, 10:59 PM
If you're just "testing" your skill. Weld some stuff together and whack it with a hammer. If it comes apart, keep trying!!!
02-17-2005, 04:54 AM
A quick way to evaluate a weld ,IMHO, is simply to look at it. If the weld metal seems to have flowed out and wetted the parent metal it's a good weld. If you have burn thru holes the metal may be oxidized, porous or contaminated with dirt or rust. If the weld looks like a jelly bean collection, don't even try to use the part as it will fall apart first chance, grind the weld off and try again. Only practice and a basic understanding of how welding actually works will give you success. I am sure everyone at some time has welded something they would rather not talk about.
02-17-2005, 06:08 AM
Alright guys. Thanks for the tips! I'll post up some of my welds later. Im mainly welding 10xx steels. Both sheet, and tube. I usually coin my welds, sometimes they flower off, sometimes they're taller, depending on my heat. Im pretty sure my penetration is good, because when I tack I get the bright orange dot on the back side.
02-17-2005, 09:08 AM
There's a LOT more about welding than most people wanna realize.
First off - WHAT material are you welding ??? "10XX" tells us VERY little. FWIW you want to stick with low carbon steel - anything under .3 percent Carbon - this would be denoted by the LAST two digits - eg. 1020 steel has .2 % carbon in it, 1010 steel has .1% carbon in it and so on. The reason that carbon is good/bad is because it is a critical factor in getting steel to be harder. More carbon by itself doen't make the steel hard, but under the right circumstances can allow it to be come hard. With hardness you also get brittleness - brittle material cracks quite easily under the righ tcircumstances.
First thing a welder needs to know is the amount of carbon he's dealing with. A general method to determine this is by a spark test. Careful inspection of the spark trail will tell you lots.
MIG's are nice for putting down pretty beads, but can easily fool you into thinking you've got better penetration than you really do. Granted for sheet metal work this will likely NOT be a concern, but anything heavier and you REALLY have to study the bead and especially the transition area between the bead and the parent metal - this is the "wetting" they are referring to. The bead should flow smoothly into the parent metal. The "orange dot" is good, but not exactly tell tale.
Run some beads and then cut them across - buff them and closely inspect your actual penetration. We used to do that and then etch them to see the HAZ. Good Stuff - can be really eye opening to say the least. Maybe a bit over the top for a home guy, but you might consider taking a class at the local vo-tech or community college - they often have excellent welding programs. And also might even have some classes in (dare I say it) welding theory. the proper application of a welded joint is as important as the weld itself.
Keep up the questions - you are on the right track.
Jacin in Ohio
02-17-2005, 09:51 AM
Jacin, thats some great information there. I normally prefer TIG, but only have access to MIG at the current time.
I just got some steel from lowes, Im guessing its like 1018 or something.
Whats the spark test? How do you evaluate it?
Some of my welds look wet, sometimes they look on top and barely blend in. Those I believe are not too good welds, correct? My friend wants me to weld up some stuff for him, however I do not know what the steel it is.
I'll try cutting my beads. Tomorrow Im going to weld two pieces of square tube together, end to end. Then lock it in a vise and smack it with a hammer. Is that a good test?
I'll look at the local tech college for college.
02-17-2005, 06:58 PM
Mike, Instead of trying to explain it - I did a search on google and found a site that does far better than I can PLUS even shows a couple of pictures.
The only thing I would add to their description is a caution about the abrasive wheel you use. I've noticed that some (probably the cheap sum flung dung versions - but that's only a suspicion) tend to impart contaminents into your spark stream thereby fooling you. To avoid this - I always keep a couple of KNOWN materials on hand - this is a good idea anyways as it is a perfect reminder to which trial we are wanting to match.
The biggest problem with welds that "looked" good is that they too can be misleading - to a point - it takes a bit of practice to really READ a weld bead. The washed in look is as important as anything, but bead size and placement are equally as important. In simple terms - it would be logical that your bead bead as large as your parent metal to achieve full strength. In addition the shape of your bead tells you alot about how much heat was used - inanother words if your transition area looks washed in but your bead profile is rather bulbous (am I making up words again?) as opposed to flattish it would suggest that it may not be near as washed in as first glanch might indicate. This is where the sectioning really helps - it is amazingly clear once sectioned.
The next thing to consider is the mechanics of the joint - a simple symetrical joint is easy, but even a simple TEE joint will require you to adjust your torch to allow equal heat into each side of the joint (equal heat being sometimes more difficult than others since each side of a TEE joint will absorb heat at different rates simply because of the shape of the material). This is another area where the sectioning will shine a bright light on my points. It seems to me that when I took MIG welding classes we spent a LOT of time sectioning welds and etching them. It didn't take long to realize that a bead could be far less effective than it appeared by a casual observation - coem to think of it - I bet that was why they constantly beat it into our heads by the repeated sections we cut.
When I did a LOT of MIG welding I eventually could get the beads washed in so well that alot of times they were mistaken for TIG welds. I'm NOT bragging - believe me there were guys in that class who could welds circles around me!!!And I bet years later when I got better they STILL could. And nowadays I reach for the TIG 98% of the time. My point is that when done properly (and under the right circumstances) it should be somewhat difficult to determine which process was used - GAS, MIG, TIG.
A "good" MIG bead ought to wash in quite well - those that are looking like they are "laying" on top are likely not penetrated at all.
The other problem with MIG especially with the smaller units - you just GOTTA have clean metal - it ain't like stick welding where they can float out the crap with a good flux - nope you need it clean to begin with!!!!!!!!
The other thing we learned while sectioning our welds was watching the soemtimes HUGE effect the various shielding gases had. Which could have a huge impact on weld penetration depth and shape. It truely was amazing. Too bad I forgot most of that :cry:
If you can, go ahead and post some pics - I bet you'll get all sorts of good feedback!!!!!!
Jacin in Ohio
02-23-2005, 04:46 AM
I think Im doing something right. Yesterday I did some welding and strength testing. The first few welds would withstand the hammer, but when hanging from a 3foot cheater bar they broke. So I just redid them until they looked right, and were strong enough until I could hang from them.
So, my final weld of the day looked pretty good. It was much flatter than the rest. I ran a bead instead of coining. Below are some pics:
As you can see, the steel tube I was welding broke before the weld. Im guessing thats good? The tube was 16gage. I broke it hanging from a 3 foot cheater bar. So this leads me to a few questions.
So, flat welds are what Im looking for usually right?
Flat welds are usually a sign of penetration?
Are beads stronger than coined?
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