[Markus]

So been reading some articles again about hydrogen in aluminium and I found the reason why aluminium tends to trap hydrogen gas.

Answer is in solubility.
In high temperatures solubility rises, specially in aluminium and it sucks a lot more gas or hydrogen than steel for example.

Link http://www.twi-global.com/technical-kno ... ny-advice/ that confirms the solubility (there are many more too). About that turbulence, I don't fully buy that one. Also they don't talk anything about molecules breaking in the arc...
Also it's good to keep in mind that fully clean weld without any porosity are very rare in aluminium. Even with TIG.


Good picture of solubility of aluminium in high temperatures. NOTICE THE HIGH PEAK AT 660°C!



Check this one too: http://www.migweld.de/english/service/d ... lator.html

[Otto Nobedder]

Markus,

I appreciate the effort you've invested in this!

You've given me much information I should either have known or found for myself, because of your own interest.

I hadn't considered the oxide layer of aluminum as a route for hygroscopic behavior. It suggests hydrogen and other molecules can be absorbed, if not passed.

Steve S

[MinnesotaDave]

Markus,

I appreciate the effort you've invested in this!

You've given me much information I should either have known or found for myself, because of your own interest.

I hadn't considered the oxide layer of aluminum as a route for hygroscopic behavior. It suggests hydrogen and other molecules can be absorbed, if not passed.

Steve S

I consulted with two science educators about this - the high school teacher had nothing to offer, seemed quite bothered that welders would even care about such topics...

The college professor discussed at length the issue - she also agreed that aluminum alloy is not hygroscopic, but that the aluminum oxide is.

[Markus]

@Steve

Thanks. It's more fun to actually know things than just assume. That's reason why I want to solve these kind of problems, even if it takes some time.


@MinnesotaDave

I'm not surprised that high school teacher didn't knew anything about it But saying that we shouldn't ever care.... Tells a lot about what kind of teacher he or she is.


Do we need this kind of information then? As welders? I would say yes we do. I believe that many of us including me will just ignore things in time, if we really don't know the reason why we actually have to do it.

Example:
Boss have told you to clean metal before welding. Well of course you will do as said, but in time you start thinking that why I'm actually doing this? Does this actually help at all? My weld on dirty metal looks just as good as on cleaned ones. So to me (to welder's eye) cleaning is absolutely unnecessary, right?

But if the welder knows that uncleaned metal may cause porosity, due to oils etc. . Perhaps then or should I say then welder understands why he need to clean the metal. Therefore he will not just make his job easier, but also improve his own skills and quality of his work.

Well that is just my opinion and nothing else.


I think I will wrap up this topic at some point and write a little new one about Aluminium's on the Welding library, where it can be easily found.

[taz]

I could not agree more.
A welder should know why he is asked to do many things. Otherwise when left unmonitored there is a big chance he will revert to doing it the way he deems fit.
If however he understands that many times the effect of his actions cannot be seen immediately or by NDT and is given the relevant knowledge there is a greater chance of doing it the right way.

[zank]

The best welders I've interacted with are very inquisitive by nature and want to learn as much as possible to further their craft. Sure, there are the run and gun guys, but I think they find their ceiling quicker.

[MinnesotaDave]

I agree with you guys - learning is as natural as it is necessary in my opinion.

[taz]

My field is mostly in petrochemical, pipelines and power industry.
Welders in these industries most of the time are judged by 2 things only.
a) How many inches they weld per shift
and
b) What is their repair rate.
A beautiful weld is something to be admired but when pay time comes the guy who can turn and burn will get more money compared to the guy with the perfect stack of dimes.
Unfortunately this leaves little room for self improvement, very few care if a welder knows why he does something.
Even if he does and for example states that a particular joint is not prepped/purged etc correctly, most of the time he will be told to shut up and weld the d@mn joint.
This is unfortunate but is the hard truth.
Other industries are different though but are outside my field of knowledge so cannot comment.

Still I like it when I meet guys that want to know more and it gives me pleasure to answer their question if I can (and then I ask them for tips to improve my welding )

[Otto Nobedder]

I have the great joy of working in a place where we are allowed to get it right. My work is in liquid hydrogen transport tankers. The danger from a failure of any kind is so great that we are allowed to do everything right, and fix anything that's done wrong. I'm never pushed to hurry.

Since these tankers roll down the same highway as my grandchildren's school busses, I'm grateful to know the company takes the responsible approach.

Steve S

[GreinTime]

I always use school bus' to pressure people into getting work done that needs done that they don't feel like paying for. Nothing causes a monumental opening of the wallet for wheel seals and the like than the question "Well, what are you going to do when your wheel end comes apart and goes flying into a busload of children? No matter how many times I put 'no warranty, no liability' in the tech's comments because you refused to have someone come in and properly repair your axle housing, it is on the shoulders of the tech and I that whatever we did today either caused the aforementioned accident or prevented it. It's not a legally binding contract, and their parents will come after us because we let it leave the shop. I can't hold you here in the State of Ohio, but it's your choice."

[Otto Nobedder]

Sam,

I'm in the unique position of being able to refuse to release a vehicle that I fail on DOT. My company will stand behind me 100%, and will call the state police if a vehicle I refuse attepts to leave the lot.

As you may assume, this never happens with our primary client, but we do occassional work for others, and sometimes they don't agree with my assessment. We've never actually had to call the state troopers, but we did have to threaten it once, and on a LHY trailer... to get them to let us replace a WAY under minimum 5th wheel/kingpin. I would not let it leave the lot, and left the yard-mule under it to prevent it leaving.

Steve S

[Markus]

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