Weld Testing

[Fred Bryant]

I am still playing around trying to learn Tig ( and use my Lincoln 175 ). I have gas welded some in the past, but nothing critical, and have braze quite a bit. I am starting to get something that looks like a weld bead now, hence the next question is: How do I test the weld? I do have the information that Dan suggested on the way from Miller, but it has not arrived yet. Also, I am not sure if it addresses weld testing.

In the past when I have brazed something that I deem critical ( failure = someone hurt, or lots $$$ in damage ) I have tested it as follows. I brazed up a sample joint. I then cut it apart and made sure that the base metal was totally enclosed in the braze. In other words, there was no base metal to base metal contact, instead there was a 5 to 10 thousands gap that was total filled with the braze material. I then beat the joint apart ensuring that the joint failure was due to a base metal failure, or braze failure depending upon the materials involved, as opposed to the base metal/braze bond. This might not be correct, but at least it made me feel better.

As for that attached sample weld, after the picture ( comments? ) I cut it into 1” strips. Since it was welded from one side only, I check each strip for penetration. Except for the beginning and end section, I had 50% to 60% penetration. On the end sections I had only about 30% penetration. I then beat each strip against the weld to failure. That is I folded the joint on to the weld. In all but the beginning and end section, the failure was a tear out of the base metal. In the beginning and end section, the failure was a tear out of the weld fillet/base metal bond. Am I OK, or am I in left field?

Self-taught, and not knowledgeable, yet. Willing to learn, all comments welcome.

Thx’s, FAB

[Dan]

Fred

My Metallurgy book states that if the base metal tears out and the weld metal remains intact your base metal needs to be preheated and post heated because the steel you are welding on is an alloy or a high carbon steel requiring this. The book also states , that if the weld had broke in two then the basemetal doesn t need a preheat. Now this is based on having produced a sound weld bead, meaning the fillet had penetration all the way to the root.

I have more to tell you but my wife is ready to go so I ll return later.

[Fred Bryant]

Reference Material

Thank's Dan. What reference are you using? Is it worth getting? As I said, I am a self taught newbee ( still being self taught ) and need to start building a reference library. At the moment though, I am sort of tapped out after outfitting the welder. I am sure you can understand.

As for what exact my test strips are? I do not know, I got about 800 of them free, if I cleaned up the cutoff station at the local fab shop. I figured that for practice, they would suffice. I would not build anything critical out of unspecified material. I also got about 800 of some 1/4" material from the same place. I figured I would use it for learning to stick weld ( questions will be forth coming, I am sure of it ). I guess I can stop my Monday and ask them if they know what the material is.

Would love to hear more.

Thx's, FAB.

[Guest]

Re: Weld Testing

Originally posted by Fred Bryant
I am still playing around trying to learn Tig ( and use my Lincoln 175 ). I have gas welded some in the past, but nothing critical, and have braze quite a bit. I am starting to get something that looks like a weld bead now, hence the next question is: How do I test the weld? I do have the information that Dan suggested on the way from Miller, but it has not arrived yet. Also, I am not sure if it addresses weld testing.

In the past when I have brazed something that I deem critical ( failure = someone hurt, or lots $$$ in damage ) I have tested it as follows. I brazed up a sample joint. I then cut it apart and made sure that the base metal was totally enclosed in the braze. In other words, there was no base metal to base metal contact, instead there was a 5 to 10 thousands gap that was total filled with the braze material. I then beat the joint apart ensuring that the joint failure was due to a base metal failure, or braze failure depending upon the materials involved, as opposed to the base metal/braze bond. This might not be correct, but at least it made me feel better.

As for that attached sample weld, after the picture ( comments? ) I cut it into 1” strips. Since it was welded from one side only, I check each strip for penetration. Except for the beginning and end section, I had 50% to 60% penetration. On the end sections I had only about 30% penetration. I then beat each strip against the weld to failure. That is I folded the joint on to the weld. In all but the beginning and end section, the failure was a tear out of the base metal. In the beginning and end section, the failure was a tear out of the weld fillet/base metal bond. Am I OK, or am I in left field?

Self-taught, and not knowledgeable, yet. Willing to learn, all comments welcome.

Thx’s, FAB

Although that's not the way welds are tested in the certification process, it's a good indication that you're doing OK.

The certifications I take are based on penetraton, leg length, bead width, concavity, convexity, and then taking all those dimensions, feed them into a complex formula, to produce the yea or nay to the test.

As a rule of thumb, if your weld tears out of the base metal, it's a good weld. It means the weld metal didn't fail, the base metal did. It is better to have more penetration then less, tho.

As Dan mentioned, there are ways to prevent certain results from happening, but we're talking "rule of thumb" here.

I am also certified in silver braze and am familiar with the testing procedures you mention. In welding the most common are face bend, and root bending of butt welds. Fillets are cut into strips and etched to bring out the penetration. 90% is the goal.

Hope this helps,

[wlbrown]

weld testing

HELLO TO ALL,
there is another method of testing.
the strips are cut, and then machined,
and then made into a "dogbone" shape.
(narrowed in the center to an exact
dimension)the weld is in the center.
these strips are then put into
a machine that pulls them, until they fail.
wlbrown

[Mowjunk]

Re: Re: Weld Testing

Originally posted by Rocky D


Although that's not the way welds are tested in the certification process, it's a good indication that you're doing OK.

The certifications I take are based on penetraton, leg length, bead width, concavity, convexity, and then taking all those dimensions, feed them into a complex formula, to produce the yea or nay to the test.

As a rule of thumb, if your weld tears out of the base metal, it's a good weld. It means the weld metal didn't fail, the base metal did. It is better to have more penetration then less, tho.

As Dan mentioned, there are ways to prevent certain results from happening, but we're talking "rule of thumb" here.

I am also certified in silver braze and am familiar with the testing procedures you mention. In welding the most common are face bend, and root bending of butt welds. Fillets are cut into strips and etched to bring out the penetration. 90% is the goal.

Hope this helps,

Rocky D, do you know what they use to etch the weld? I cut some of mine with a hacksaw and I couldn't tell where the weld ended and the base metal started! Just curious.......