American Welding Society Forum
I failed X-ray due to porosity. 1/4 to the edge of the weld. I had numerous porosity through out the weld. I have been running this wire for many years, this is my first failure. I am welding 1 1/2" Plate x 12". This is a F.E.M.A. test. It was raining that day, with high humidity and in a shop, but I preheated. The fit-up had mill scale and I cleaned it as best as possible. I am a field welder and so tested with field conditions and equipment. A Miller 300D was used, c.v. of course. I could see no signs of porosity. I had correct amps. and volts for .072 wire. I did have an excessive amount of lead rolled in coils on the back of a truck, power-up would make the leads jump. Any help is appreciated.
did you clean between each pass making sure all foreign materials were not present.
If you are sure the metal was clean and dry, and there was no draft coming through to blow away the gas, I would say you probably had a leak in your gas line somewhere.
There are other possible causes though, like contaminated gas or wire, but I would do a leak check first.
Ive had problems when wire brushing and cleaning between passes where oil from the power tool you are using displaces itself onto the weld area causing problems that may be undetectable.
This might sound silly, but I have seen travel and work angles that lead to porosity because the shielding gas cannot cover correctly. Fixed the way the guy was holding the gun and he had no more problems. I mentioned this because sometimes people are looking for something in the equipment, material cleanliness, or electrodes for the problem, when it is as simple as wrong angles to the work piece.
Just another thought,
E71T-8 is an all position, self shielded flux core wire that operates on DC negative polarity. Porosity is often a result of contamination that is turned into a gas and is trying to escape the molten puddle. Excessive travel speed(doesn't give the gas time to escape), improper electrode drag angle, excessive voltage, too short of a stickout, too low of a wire speed and old or rusty flux core wire will also cause porosity.
While I was typing I see Mike had some of the same ideas, give em a try and see if it helps,
Something else to consider is to try another roll of wire, hopefully from a different lot number.
It is very common to encounter porosity with flux cored that you can't explain. Changing wire often helps. When you consider that most FCAW wire is manufactured by folding a flat ribbon of metal around a line of granular flux material, and that flux material is "dribbled" onto the ribbon at high speed, it's easy to see that the possibility of having a segment of wire without flux in it is not unheard of.
Also, most FCAW wire has a seam in it that could allow moisture inside under high humidity conditions especially if the wire has been on the machine for a while.
Not trying to put down the manufacturer's here, they all do a good job considering the difficulty in making the stuff. But the rule of thumb at our shop is, when you have checked for all the common causes of porosity and still have a problem, then change out the wire. That usually cure it for us.
Hope you solve it
I agree with CHGUILFORD. Flux cored wire has a "shelf life". It will pick up moisture. There is a procedure for keeping flux cored wires dry sort of like E7018. I also agree that gun angle has a lot to do with it, but you're an experienced weldor and probably already knew that.
I hope I didn't insult anyone with my comment(it wasn't meant to). Sometimes the obvious doesn't jump out at you, so I mentioned it.
1. Are you doing the Supplemental Welder Qualification w/restriction plate? For some reason, even the best welders I know are having trouble with this test. Not sure why though. It is typical of what they encounter on a daily basis.
2. Also, I did not read on the responses but what brand wire are you running? BIG difference according to the welders. I agree that the different manufacturers electrodes operate distinctly different, but that is more of a "operator appeal" attribute of the wire.
John W, go easy on the forum. (Besides, you wouldn't hurt a fly if it landed in your milk. You would politely show him the exit... ;-)
Thank you! All of you have been very helpful. I am sure I will pass my next radiograph with confidence.
Just curious, Rich. You stated the weld leads were extremely long and coiled on the truck. Do they always jump at power up? You said you had the correct voltage & amperage. Was this measured near the arc or on the power source? Voltage drop is something to be concerned with whenever you are welding. Coiled leads can create resistance and therefore accentuate the voltage drop from long leads. When testing we try to measure the volts and amps near the arc as possible. Flux-core does seem to be one of the hardest processes to control and isolate a problem variable. Good luck.
I had the same problem with Lincoln 203 mp self shieled and it turned out to be the 50 or so feet of lead coiled up in the welding trailer.
Once I straightened them out on the ground....no more problem!
What stickout are you maintaining? What does the manufacturer of the wire recommend?
I am doing The S.W.Q. /w restriction plate. 3/8 root. I run 2 passes in the root to avoid trapping slag. I Know that inclusion will show itself after many passes, we call it a worm hole. My root is ran rather fast, but never had a problem. I did have fresh wire, Lincoln. Stick out calls for 1/2" to 1" and I maintain these parameters, adjusting for conditions while welding. Two things mentioned made me think. Air-tool oil and drag angle. I test again tomorrow. My shop fabbed the test plate again. What a mess! going to take it apart and clean it this time! Thanks again.
I would run the root pass in a single pass if possible. You will still be within the maximum bead width range. There is not a lot of room to work with a grinder down there, particularly with that friggin restriction plate in the way. I tested 3 welders 2 weeks ago with a 1G @ 3/8" root opening. I encouraged all of them to do the same. The guy who failed several times before passed this time around. He busted out twice on the root pass previously.
Work and travel angles are often the source of wormholes in these welds if your running NR-232. Watch your voltage as well. Don't overdo it on this parameter, also the source of wormholes with 232.
Did you pass?
??"My shop fabbed the test plate again" ?? I always have the welder do his own fitup. Good luck and let us know how you did.
I too let the welder fit his own test up. I'll give instruction if need be but, it's all in the WPS anyway. I like to see if the welder is able to read the WPS and make out what the fit up dimensional criteria/tolerances are. Also I pay attention to see if he/she cleans the backing plate and groove faces with the grinder before they fit it up and then preheat the joint as required. All these things tell you if they have ever done this before or whether they will simply rush in and slap it together and start welding that baby up. It's not really a timed event, although it should be accomplished in a reasonable amount of time.
Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill