Porosity - EN8

[PSweeney]

Hi, had some major issues over the last week with porosity, I started welding some saddles onto an axle, ran a nice bead then ran out of gas. Went and got anoher bottle then jot a porous weld, I blamed it on the oil impregnated axle case, so I ground it out, cleaned the inside as best I could but swapped to mig, all welded up no probs.

Had another job to do, basically a 40mm EN8 turned to a stub and welded to 3mm plate. I choose EN8 as a medium strength steel. I bored the 3mm plate and intended to weld both the stub from both sides. 3mm plate and stub was ground back to bright and de-greased wth brake cleaner thoroughly before I started. I could not have got it cleaner. Welding the backside immediatly I got porosity, crackling, spitting and chasing an air bubble in the pool. I thought maybe the gas was ifffy, So I topped immediately, ground my tungstem (swapped from red to gold too and on a fresh wheel ) same happended again.

Was using ER70S-3 rod, about 90a and 10lpm. I ran beads on the 3mm plate (mild steel assume EN3B) alone, perfect. So it appears to be the EN8 material. Its been turned, using carbide tools and water based coolant, and I wondered if this has contaminated ? but even welding on un-turned section yeilds porosity. Whats my probloem here ? is EN8 the wrong material ?, could this be from the turring ? can't be the rod as it's occuring even before I dip ?

 

[Paul.]

Are you sure its en8, it wouldn't be the first time that a lump of en1a has been supplied instead by mistake, I would have thought that rather than porosity you would be more likely to have problems with cracking, a bit of preheat on heavier sections helps with that
I used to make trolley frames from Mild steel channel, with axle pins turned from en8 welded on, these were stick welded using low hydrogen rods and never had a problem.

 

[doubleboost]

I have just tried a bit of EN8 with tig good clean arc
This is deffo EN8 it was bouhnt in for a crank pin

 

[PSweeney]

Just checked the invoice, I've somehow ordered en1a, what a tit, thanks guys

 

[Windy Miller]

Slightly off topic, but none the less its still relevant here, you mention cleaning with brake cleaner. I seem to remember something about this being SERIOUSLY dangerous prior to welding. What's that dreadful gas called? Phosgene? Isn't there a risk of the brake cleaner remaining in minute cavities and producing this stuff when it gets near the arc? Wasn't there some guy in the US that nigh on killed himself with one tine little puff of the stuff?

 

[PSweeney]

same as any solvent, thinners or acetone, you wouldn't weld over it. If its fully dry, its no problem

 

[hotrodder]

Slightly off topic, but none the less its still relevant here, you mention cleaning with brake cleaner. I seem to remember something about this being SERIOUSLY dangerous prior to welding. What's that dreadful gas called? Phosgene? Isn't there a risk of the brake cleaner remaining in minute cavities and producing this stuff when it gets near the arc? Wasn't there some guy in the US that nigh on killed himself with one tine little puff of the stuff?

The brake cleaner thing is a mix of half truths and utter drivel, read this thread... http://www.mig-welding.co.uk/forum/...-and-welding-warning.13507/page-2#post-559455

I think this is the story that started all the nonsense... http://www.brewracingframes.com/safety-alert-brake-cleaner--phosgene-gas.html note in particular

I started welding across a really pitted area and came across a couple of drops of cleaner still left in a deep pit

After about 10 minutes I went to the office at the house and sat at the computer to check the warnings on the brake cleaner can when my whole left side started shaking for about 10-15 minutes. The can said ‘Vapors may decompose to harmful or fatal corrosive gases such as hydrogen chloride and possibly phosgene.

so we're off to a good start... don't bother reading the label on the can that spells out how nasty it is, just start welding on a part that's still wet with a solvent that came in a container covered in safety warnings It then goes on to spout some utter nonsense about it reacting with (the noble gas) argon

The chemical in the brake cleaner is Tetrachloroethylene. When this chemical is exposed with excessive heat and argon (used in MIG and TIG welding) it also produces phosgene.

Brake cleaner in the UK is NOT chlorinated

 

[Bill Edwards]

To save you a lot of reading the stuff you'll purchase in the UK won't be an issue, the main thing to worry about it simply the fact that it is very flammable and leaving an aerosol near the welding/grinding bench, or rags that have the stuff on, is a big no as it burns quite well. Otherwise, don't worry.