Testing Weld Strength

E

ErikD

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Dec 5, 2000
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I am still learning to weld, and would like some more information on how to test the strength of my welds without expensive equipment. I am using a Lincoln-Electric Weld-Pak 100, a wire feed welder that runs off of 110v. I don't have the MIG kit, yet anyway, so I am stuck doing flux core welds for now.

The latest test sample I welded up was a piece of 1" square tubing, with 1/16 wall thickness. I cut two 1' sections, and welded them back together. I then tried my best to break them apart. First I stuck them in my vice and tried to break the weld that way. Well, the vice is bolted to my workbench top, an old 2 x 6 plank. All I was able to do was rip the vice out, and split the board apart. Then I decided to wedge the tubing between the floor joists, and some other tubing bolted to the joists. Well I was able to hold myself up and support all my weight without breaking the weld.

I am out of ideas on how to insure that my welds are as strong as they could be. Is there anything else that I can try to test out the strength of my welds? Have these tests shown that they are strong enough, or should I test further?

Thanks in advance.
 
of course the best methods fall outside the parameter of no expensive equipment, but there are some good ways to see if the welds are good. Your destruction tests are good. If the piece fails at a point that is not the weld that is good. Another suggestion would be to cut the weld in half along its length. Look to see if you got full penetration and if there are slag pockets or voids. Or you can cut strips perpendiculat to the weld to see the cross section of the weld. Then bend them 180 degrees. Mild steel should do this. When you get the shield gas set up if you continue to run flux core wire you can get some very nice looking and clean welds.

WS
 
Insanity is right.A major problem for new welders is to not get enough penetration Cutting the welds then grinding them carefully and with fine grinding wheel will show penetration ,voids ,porosity and other problems. Bending tests are helpful also. A book like Audels Welders Guide show some standard bending tests. Welds usually break in the heat effected zone. Get a stronger bench and vise . This is a big topic , too big for just quick answers, get some books and learn , and practice , practice.
 
I do have a number of books on welding, and have been practicing as much as I can. I have gotten much better too, my first attempt fell apart with a soft tap from my hand!

About cutting the weld to look for penetration, what should I be looking for? I am thinking that if I get 100% penetration then once cut and smoothed the welded area should look the same all the way through. If I didn't achieve 100% penetration there will be some marked line where I did penetrate to. Is this correct?

I am really asking here because the books I have leave it somewhat vague, or I can't really tell for sure with the photos shown. I am really just seeking some advice / guidance from other welders with more experience. Thanks again.
 
For example, if you are welding 1/8" thick material in a butt weld that weld should penetrate 1/8". On thicker material that may only achieved by chamfering the material. If the weld is only 1/16" you have ,in essence a crack for the other 1/16" and that will invite a fatugue failure. The weld on top should not be undercut because that too will be a weak point for fatigue failure.Again mild steel usually is a problem of incomplete penetration ,when you get into alloy or even tool steels it gets far more complex.
 
Is there anything else that I can try to test out the strength of my welds?

Anything I need tested I give to my six year old...if she does not break it it is unbreakable! Oh, you said inexpensive...nevermind. :p
 
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