porosity problem

[Andy]

Hello,

I have a PP256 that I'm having porosity problems with. I'm welding 1/2" plate to 1/4" 3x3 angle iron. One weld will go fine, then the next is a mess. I ground down to bare metal and cleaned with acetone. The tungsten is sharp and clean. I'm using a #7 cup with a gas lens. The argon is set to 10L/min. I'm maxing out at about 250 amps with the peddle. The ground is attached to clean bare metal on the angle iron. Any idea what I might be doing wrong?



Thanks,

Andy

[arctime]

It might be one of several issues. Maybe not enough argon flow (or it is getting blown away). Dirt/oils on the filler wire. Most likely, IMHO, it could be contaminants being pulled in from the base metal. You could try running at 200A as going a bit lower will most likely bring up less base metal in the pool. Have you tried your technique on another scrap of known quality steel? I've had problems in the past using to many amps when it really isn't necessary on very heavy metal. I've had better results with several layers at 200A using a lay wire technique when joining very thick steel instead if trying to get it done all at once.

Arc on.

[performance]

Why are you using that much amperage? Making a huge, globby weld like that isn't the best idea. Make multiple passes. 120-150 amps should be about all you need. If you are using that much amperage, it's likely you are overheating the tungsten.

[Andy]

Arctime,

I tried turning up the argon yesterday, but that didn't seem to help. I'm inside, with no breeze. Maybe I'll hold my breath just to be sure The filler wire looked clean, with bright shinny copper cladding. However I didn't wipe it down. I will try lower amps. That could be it, as I haven't had this issue with welding thinner metal. I'll experiment on some scrap. I don't know the quality of the metal, but it was purchased from a reliable local metal retailer.

Thanks,

Andy

[Andy]

Mark,

I was going by the 1 Amp per thousandths rule of thumb. Bad rule? Between you Arctime, I'm convinced I'm way high on the amperage. Thanks.

Andy

[geezer]

Arctime,

I tried turning up the argon yesterday, but that didn't seem to help. I'm inside, with no breeze. Maybe I'll hold my breath just to be sure The filler wire looked clean, with bright shinny copper cladding. However I didn't wipe it down. I will try lower amps. That could be it, as I haven't had this issue with welding thinner metal. I'll experiment on some scrap. I don't know the quality of the metal, but it was purchased from a reliable local metal retailer.


Thanks,

Andy

Try turning down the argon,,,cup size and Litres/min are about same...

[geezer]

I forgot to mention that standard cup size of 7 would be 7L/min and diffuser cup would be 1/2 of that... say 4L/min...quite a bit lower than your current setting of 10L/min....check CK world tech specs...page 4

[Andy]

Mike,

I lower it to 130 amps, and varied the argon from 5 10 15 L/min. I just tried laying beads and bright shinny metal. About half the time I can lay a bead without porosity. This is without changing settings, just trying to lay another bead and it goes to hell. I'm wire-brushing the are after each one.

I don't want to blame the tool for my lack of skill, but I do have my doubts. The pulse mode never worked, and the plasma cutter gave out long ago. When I first got the machine the front bezel was badly broken by the UPS gorillas. You guys replaced that. Is there anywhere I can get the machine check out / fixed locally? I live in Austin Texas. If not, can I box it up and send it your way? I want the confidence that its not the machine.

Thanks,

Andy

[Andy]

Gezzer,

I did take it down to 5, but I'll try going lower.

Thanks,

Andy

[Rambozo]

Mike,

I lower it to 130 amps, and varied the argon from 5 10 15 L/min. I just tried laying beads and bright shinny metal. About half the time I can lay a bead without porosity. This is without changing settings, just trying to lay another bead and it goes to hell. I'm wire-brushing the are after each one.

I don't want to blame the tool for my lack of skill, but I do have my doubts. The pulse mode never worked, and the plasma cutter gave out long ago. When I first got the machine the front bezel was badly broken by the UPS gorillas. You guys replaced that. Is there anywhere I can get the machine check out / fixed locally? I live in Austin Texas. If not, can I box it up and send it your way? I want the confidence that its not the machine.

Thanks,

Andy

There really isn't anything with the machine that can cause something like that. DC TIG is about as simple a process as you can get, you can even do it with a few car batteries for a power source. The things to look for are gas shielding problems and overwelding the metal. First thing check your torch for leaks and any place where air can get sucked in. Since you have intermittent issues, especially check for things that move, like where the hoses attach at each end. The next thing is total heat input and filler metal. TIG rod contains deoxidizers to help the puddle flow and wet out, but if you go over the same area too long without adding more filler, you will get all kinds of bubbles like that. Most people starting out, tend to go too slow. You will have to figure out if there is anything you are doing differently on the welds that are giving you problems. Once things go bad, don't try to keep welding to fix it, you will only make it worse. Stop, grind it out, let it cool and start over. Also with thick pieces like that, you have to watch that you don't get things too hot. The first weld might go great, but then the second doesn't, because the piece is too hot when you start. There is a limit to interpass temperature for most materials.

[Andy]

Rambozo,

Thanks for your tips. I will check hoses etc.

Heat could be an issue, though I've seen the porosity on a cold (70F) piece as well.

I wish I had the facility to video it. I'm seeing the puddle bubble up, like there is gas trapped inside. Maybe I am going too slow. The puddle doesn't advance as well as I've seen on sites like "Welding Tips and Tricks". I have noticed porosity just at the start of the weld sometimes, so that would make sense that the deodorizers are absent.

I'm getting pretty good at grinding it out. Is this what its like to be a dentist?

Always more to learn

Thanks,

Andy

[TheGary]

From your picture of the piece I believe you are pulling in air somewhere . Try lengthening your post flow and plug the cup outlet so that the flow pressurizes the line and torch. then check to see if you hear a leak somewhere, if you do fix it. When the gas is flowing through the hose it will draw contaminated air in at any leak point because it will cause a vacuum at the leak.

[cadguy]

Rambozo,

Thanks for your tips. I will check hoses etc.

Heat could be an issue, though I've seen the porosity on a cold (70F) piece as well.

I wish I had the facility to video it. I'm seeing the puddle bubble up, like there is gas trapped inside. Maybe I am going too slow. The puddle doesn't advance as well as I've seen on sites like "Welding Tips and Tricks". I have noticed porosity just at the start of the weld sometimes, so that would make sense that the deodorizers are absent.

I'm getting pretty good at grinding it out. Is this what its like to be a dentist?

Always more to learn

Thanks,





Andy

It looks to me like you are pulling the carbon from the sides of the angle.
You had said you ground the metal, but did you grind the grey carbon from
the side walls of the angle? You have to grind it back from the weld zone
far enough that it can't be pulled in to the puddle. It can be pulled in
from the bottom of the weld through the joint.

[johnson697]

sometimes when the weld is already contaminated already you have to actually cut it out with a die grinder or if you have crystallized the metal by over welding it you have to cut it out also.

[Andy]

Rambozo,

Arrgg, stupid forum ate my previous reply. Anyway, I checked the argon hose up to the welder. No leaks. Any leak would have to be between the gas solenoid and the front connector. Pulling that apart is project for another day. I have the stock cable and torch, which makes me feel like a python wrestler at time. I want to get something more supple. I have problems maintaining smooth movement with this one.

I decided to go back to basics and just lay beads on 1/8 plate. That was a worthy exercise. At one point I methodically adjusted the amperage and noted the setting next to the weld. I did have some issues with porocity, but mostly at the start and end of the welds. Adding filler as soon as the puddle formed to care of the start, and better tapering on the peddle to care of the end. I only weld sporadically; it apparent my 'skill' has a short half-life. A couple hours laying beads and I'm much better. Still need more practice.

I put on a new silicon carbide grinding wheel to eliminate that as a source of contamination. The new one will only be used for tungsten. I'm going to get new gloves as well. Mine are ratty and have been used to hold stuff at a polishing wheel. Pretty soon I'll be working in a virtual clean room

Thanks, Andy

[Andy]

Cadguy,

I ground all sides a few inches back from the edges. Its possible I didn't grind deep enough. When I was doing some practice pieces today, I used a 36 grit flap disk. That did a much better job than a grinding disk.

The threaded 1/2" plate was milled and wiped down with acetone, so it should be fine.

Thanks, Andy

[Andy]

Johnson697,

I may have to cut back further. I was really surprised how deep I had to go to eliminated visible pinholes. They seem to be the cancer of metal.

Thanks, Andy

[Rambozo]

You don't need to pull it apart to check for leaks. Your flowmeter will show anything big enough to be an issue. Just crank up your post flow time, then, as Gary said, cap the end of the torch during the postflow. The flowmeter should drop to zero, if it doesn't, you have a leak. The typical places are at the cup insulator junction (usually from using a mismatched insulator and cup), at the backcap (bad O-ring), or at the quick release.

[Andy]

Rambozo,

I tried covering the end of torch, but I can't keep a good seal. The end of the torch blows up like a balloon and I loose the seal. I tried turning the flow way down, to 1L/min. It does not quite go to zero, but close. This is with the cup and insulator off. Sure wish it had a thermally activated fan; no chance of hearing any leaks.

I've wanted to get a smaller torch for a long time, so this is as good a chance as any. My argon is getting low, so I'll get that refilled as well. Eventually I'm sure to run out of things that are NOT the problem.

I really appreciate everyone's help here.

Thanks,

Andy

[Andy]

My welds are back to normal, yeah!. I'm still not certain on the exact cause, though I strongly suspect bad argon. I still had about 400psi on the gauge, but decided it was worth 'wasting' a bit of gas anyway. After I changed out the bottle the problems went away. I also added a Miller Coolmate 3 that I found locally for a great price. Up until I started my current project, I never went over about 140 amps. When I bought the welder, they said the #18 torch was good up to 160A without cooling. To go above that, I temporarily connected the garden hose and gave the yard a little extra water. Anyway, the torch is now cool.

Wanting something smaller, I bought a CK 20 water cooled touch from Everlast. It took 15 days to get here. UPS lost the shipment. I didn't think to mention that I had the coolmate and not the Everlast cooler. The coolmate uses barbed hose connectors. In my hurry to get it connected, I cut the quick-connect off the argon line instead of the water return. D'oh. I won't be changing the torch often, if ever, so having quick-connects for the water lines doesn't really buy me much. I'll cut the quick connect on the water supply line and then find a way to re-crimp the quick connect for argon line. I couldn't find a hose clamp small enough. I'll have to try another hardware store tomorrow.

Thanks,

Andy