I have a question about contamination on metals, what really causes this ? Let me rephrase that, I know what causes it but let me explain my situation. I have a few pieces I'm welding together for customers, the one piece has always been consistent, never had issues at all. Now this other piece is what is causing my problems, I'm 99% sure its this piece. I have cleaned it, I have cleaned everything else, rod and what not. I know for a fact its not on my side thats causing this issue.

So my question is what could be causing this ? Could it be the tool they are using to cut this metal ? Does cutting fluid ever cause issues down the road ? Its weird because I have to weld on both sides of the piece, and the one side I never have issues, then when I move onto the other end, I get contamination really bad.

So I'm open for ideas, also if it really matters its mild steel. The metal itself looks very clean.

 

I weld aluminum at work all day long. Some of the stuff they use to cut the aluminum with seem to stay with the metal no matter how much you clean everything.

 

What type of mild steel? Tube, flange, etc? Is it SS to mild steel, or mild steel to mild steel on the weld? It's very common to have a grey looking weld on mild to mild.

 

some of the cutting fluid we use in the bandsaws at work can cause porosity on mild steel. its not very often but if i get a batch of parts I have cut that starts welding like **** i just clean with acetone and its fine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">What type of mild steel? Tube, flange, etc? Is it SS to mild steel, or mild steel to mild steel on the weld? It's very common to have a grey looking weld on mild to mild.</TD></TR></TABLE>

Mild to Mild, its tube as well. I know the grey looking weld, but this stuff is popping and leaving the beehive look.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch &raquo;</TD></TR><TR><TD CLASS="quote">some of the cutting fluid we use in the bandsaws at work can cause porosity on mild steel. its not very often but if i get a batch of parts I have cut that starts welding like **** i just clean with acetone and its fine.</TD></TR></TABLE>

Tried that as well, all the normal stuff I have tried. Its weird because it seems like at times I can start ( if I hear it starting to start to hiss and blow out ) then start back up and it will be fine. This might lead you to think its my torch, or issue on my side but its not. I know for a fact its not.

 

hot rolled ms, or cold rolled? has it been machined at all?

 

Sounds like you're hitting some hot roll scale...

 

Tubing? Like 16G? Probably didn't take all the scale off on one side, when you weld say a 16g mildsteel downpipe you need to clean the scale off the outside AND the inside, otherwise when you get full penetration you bring up some scale back to the surface than it looks like a mini 4th of July while you are tiggin. If you aren't used to tigging mild steel you need to clean it like a ****, way more than you do on stainless or Al, make sure you get ALL the scale off both sides, it should be pretty shiny before you weld it. If you set it all up right you should get great colors out of welding, mildsteel, if its a dull grey your probably too hot and not enough/proper gas coverage.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by weiRtech &raquo;</TD></TR><TR><TD CLASS="quote">hot rolled ms, or cold rolled? has it been machined at all?</TD></TR></TABLE>

It has been flat cut on one side, and has a round cut ( radius cut ) on the other side. It looks like it has some mill scale on it, its taken off though before I weld but I still have the issue.

I have the issue only on the flat side, never on the radius cut.

 

With mild steel I always hit welded area with some sort of abrasive, go over it with a cartridge roll, cutting/grinding disk, flapper wheel, blending wheel etc, its gotta be really really clean.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dave@passenger &raquo;</TD></TR><TR><TD CLASS="quote">With mild steel I always hit welded area with some sort of abrasive, go over it with a cartridge roll, cutting/grinding disk, flapper wheel, blending wheel etc, its gotta be really really clean.</TD></TR></TABLE>

i do this as well without any problems usually... but if you are continuing to have contamination issues i'd take a wire brush to it as the last step. using abrasives to remove/clean material poses the risk of leaving some abrasive compound embeded in the steel.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by weiRtech &raquo;</TD></TR><TR><TD CLASS="quote">

i do this as well without any problems usually... but if you are continuing to have contamination issues i'd take a wire brush to it as the last step. using abrasives to remove/clean material poses the risk of leaving some abrasive compound embeded in the steel.</TD></TR></TABLE>

Sorry yeah I probably should have clarified that, I always use a wire brush after I use an abrasive/cutter of sorts. Also I haven't had the best of luck using acetone to clean ms, I have better results using alcohol.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dave@passenger &raquo;</TD></TR><TR><TD CLASS="quote">With mild steel I always hit welded area with some sort of abrasive, go over it with a cartridge roll, cutting/grinding disk, flapper wheel, blending wheel etc, its gotta be really really clean.</TD></TR></TABLE>

I did do that, after I noticed I was still having the issue, but the issue was still there.

I had a few pieces to test on, it seems like when using stainless rod its a little better, its not gone but better. I tried my mild steel rod on something else as well, with out a problem it welded. So I know its not my rod.

Also if I have the puddle in the molten state and let off the pedal quickly, the beehive look does not form.

 

If you just have to cover something up and its not structural use the pulse feature on your machine, it'll help cover up the contamination

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dave@passenger &raquo;</TD></TR><TR><TD CLASS="quote">If you just have to cover something up and its not structural use the pulse feature on your machine, it'll help cover up the contamination </TD></TR></TABLE>

I don't think the pulse would help either, well maybe it would but I have never used the pulse on this machine, never had to. Thanks for the tips

 

a lot of the time when you have to weld both sides of something you get "blistering" on the other side. That will DEF contaminate your weld. Make sure you use an abrasive to clean that off before welding again. Good luck

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RCautoworks &raquo;</TD></TR><TR><TD CLASS="quote">

I don't think the pulse would help either, well maybe it would but I have never used the pulse on this machine, never had to. Thanks for the tips </TD></TR></TABLE>

I know a guy that did it a couple times in a bind for non structural pieces (cough)
It does work a bit.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Teglove2 &raquo;</TD></TR><TR><TD CLASS="quote">a lot of the time when you have to weld both sides of something you get "blistering" on the other side. That will DEF contaminate your weld. Make sure you use an abrasive to clean that off before welding again. Good luck</TD></TR></TABLE>

I know what you mean but I don't have to weld both sides, what I ment was both ends

 

try flipping the part so that the gases created by the welding process can vent out of the end of the tube rather then trying to vent thru the seam your trying to weld.
This sometimes happens especially when your welding tanks. Try to keep the weld area lower so that the gases can rise and not try to come thru. You may have some coating on the tube that is not reall obvious. A pic would help especially of exactly how your welding it and also the porosity.

609-851-2810

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KFMRC &raquo;</TD></TR><TR><TD CLASS="quote">try flipping the part so that the gases created by the welding process can vent out of the end of the tube rather then trying to vent thru the seam your trying to weld</TD></TR></TABLE>

Its not really a sealed portion though so I don't think thats the issue.

 

post up some pics of the parts, can't hurt

I machine my own flanges and weld thousands of them. I've had this problem a few times when I didn't mill all the scale off. Wire brushes and wire wheels won't remove this scale. It just shines up and you can't even tell it's on there. Once you hit it the scale jumps onto your tungsten and rides up. Black soot, the whole 9.

I clean up my material with a wire wheel on a die grinder. The flanges are either machined HRS or clean CRS. The pipe is aluminized. The aluminum coating causes some graying of the weld, but I still get an even rainbow all the way around the weld.

Evan

 

I used a wire wheel as well, but nothing really chance, not even the look of the metal.

 

it could be magnetized. that would cause wandering arc and contamination.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cua0 &raquo;</TD></TR><TR><TD CLASS="quote">it could be magnetized. that would cause wandering arc and contamination.</TD></TR></TABLE>

But the other end welds fine, and there is only about a 4 inches from end to end. Also the piece is cold rolled and the side I'm having issues with is cut on a bandsaw using coolant

 

Pictures...