[Otto Nobedder]

Here's a simple comment on a very different engineering topic:
http://www.finishing.com/225/98.shtml

[MinnesotaDave]

Dave, even steel will take on water (Braehill will attest to that).

However, I'll have to do as much google as you to source it.

I will do so, because I'm now interested in the physics behind it, and maybe Len can comment with some sources.

Steve S

It is interesting to me as well - I'll run it by the science lady tomorrow and get her thoughts on it too.

I already know from prior conversations she does not believe steel will absorb water.
This could be a pretty good conversation tomorrow.

[Superiorwelding]

Dave, even steel will take on water (Braehill will attest to that).

However, I'll have to do as much google as you to source it.

I will do so, because I'm now interested in the physics behind it, and maybe Len can comment with some sources.

Steve S

I'm in!!
-Jonathan

[MinnesotaDave]

Here's a simple comment on a very different engineering topic:
http://www.finishing.com/225/98.shtml

This sentence has two points that may, or may not, help

"...but it gives the total aluminum content as aluminum sulphate as well as insoluble content of the raw material used for manufacturing purpose."

Aluminum sulphate is hygroscopic (if I understand other sources correctly)
But then it throws "insoluble content of the raw material" into the mix to purposely throw me a curve....lol

[Superiorwelding]

Hey guys, this is a great and interesting topic. How about we start a fresh thread, the information will get buried in this topic.
-Jonathan

[Otto Nobedder]

I may have thrown that link up too fast, in fact.

I'm seeing the same things, including the hygroscopic nature of aluminum oxide, immediately present on all bare aluminum.

Not done looking, though.

[MinnesotaDave]

Here is an answer for "why a soda can does not leak"

(Way way way past my schooling though)

image.jpg (91.08 KiB) Viewed 1378 times

[Superiorwelding]

Yeah, that ol Van der Waals force, gets you every time

Did anyone else feel a little dumber after reading that?

Seriously though great find Dave. Start a new thread on Hydroscopic so the info doesn't get buried.
-Jonathan

[MinnesotaDave]

Yeah, that ol Van der Waals force, gets you every time

Did anyone else feel a little dumber after reading that?

Seriously though great find Dave. Start a new thread on Hydroscopic so the info doesn't get buried.
-Jonathan

Hey now, watch your typos that's hygroscopic - lol

....and yes I did feel a little dumber - rats

[MinnesotaDave]

Ok, one more post before I decide if I need a new thread (or maybe my head will explode first)

Here's my working theory...

If the "cubic closest-packed structure" of aluminum uses 74% of the space.
And the atomic radius of aluminum = 0.125 nanometers
And the water molecule is approximately 0.275 nanometers in diameter (0.1375 nm radius)

Then does that lead us to the conclusion that a water molecule cannot fit through the remaining "holes"??

Feel free to check my conversions and math/science in general as needed....

(I also found references to list the diameter of water molecule at 0.29 nm, or 0.145 nm radius)

image.jpg (42.13 KiB) Viewed 1374 times

[Superiorwelding]

Yeah, that ol Van der Waals force, gets you every time

Did anyone else feel a little dumber after reading that?

Seriously though great find Dave. Start a new thread on Hydroscopic so the info doesn't get buried.
-Jonathan

Hey now, watch your typos that's hygroscopic - lol

....and yes I did feel a little dumber - rats

Good catch, my apologies
-Jonathan

[Braehill]

I'm not sure that I can agree or disagree that Aluminum as an alloy is actually hygroscopic. I do know that different Aluminum compounds are in fact hygroscopic, such as Aluminum Oxide, Aluminum Sulfate and I believe Aluminum Hydroxide. Maybe during the welding process the oxide portion might become hygroscopic but I don't know that for sure.

I think that the fact that a material can adsorb moisture doesn't automatically qualify it as hygroscopic. I think of things that readily attract and absorb moisture as hygroscopic such as Calcium Chloride. There's a difference between adsorb, where the surface gets coated, and absorb where it actually combines with something and changes it's make-up.

Outside of that, I don't think I can add any scientific facts to the hygroscopic conversation.

I actually think that the original problem is due to too much heat in the base metal resulting in an undesirable alloy causing the dull weld puddle, but that's just my opinion, and I have nothing to prove that either.

Len

[kiwi2wheels]

For what it's worth, I've seen a lot of parts ( pressings and machined pieces ) in Europe welded with 4043 that have the surface appearance the OP is questioning. And these are welded by guys who are full time welder /fabricators.

I'm wondering if it's in the rods, as here the 5356 also finishes clean. It would be interesting to see if rods with manufacturer certification of origin would be any different.

What about the base metal I am welding? Does 6063, and 5052 have any issues specifically with the 4043?

No, 4043 is a recommended alloy for certain applications. The components I've seen were from 5754 and 6082, all welded with Euro built inverter machines. I don't know the origin of the wires, with the amount of stuff coming from China, I think there is always an unknown in the equation. Consider the problems that can arise sometimes with " mild steel " tube and sheet.

[kiwi2wheels]

Yes, I too get it with my old Dialarc HF and usually I have to lower my amps a little and it gets shiny, never as shiny as 5356.

Len


Sent from my iPhone using Tapatalk

Thanks Len.

[Markus]

This is getting serious now! Good

Aluminium does have face centered cubic just like austenitic stainless, but that doesn't answer the question why it's hygroscopic. To be honest I don't know why it's hygroscopic. I just have read that it's, but hey that is what makes things interesting. I mean when you really need to study deeper and you learn totally new things about the material.

We already had one discussion here about austenitics stainless grades in low temperatures etc. Which is unfinished btw, but now we are covering aluminium also. This is good imo.
Not that it's important stuff for welder, but it doesn't hurt anybody? Right?

I think it would be ideal to start a new thread about this. Gather opinions and things we have learned. Merge those and add a little topic in welding library where it can be found easily in future.

[Superiorwelding]

I think it would be ideal to start a new thread about this. Gather opinions and things we have learned. Merge those and add a little topic in welding library where it can be found easily in future.

I second that! I have began my research although I am not yet ready to post. I will say this is a interesting topic and one we rarely consider although we actually see the effects in our everyday welds.
-Jonathan

[Tater]

Tell me if this is correct- you are using ER-4043 filler metal?

My shop has one qualified process using this filler. The parameters are as follows:

Aluminum/aluminum based alloys, similar base metals (or base metal repair)
Base material type Aluminum castings
thickness range 0.060" - 0.500"
Process GTAW
All joint designs
Min preheat 60-deg F
Interpass temp 300-deg. F
Filler metal type MIL-4043, ER4043, or 4043
Torch shielding gas Argon/Helium
Shielding gas flow rate 20-40 cfm
Tungsten electrode dia. 1/8"
Filler metal size 3/32" dia.
Amperage range 60 - 200 AC

I don't know squat but to me the pictures suggest two possible factors, wrong shielding gas or interpass temperature.

[Markus]

"When a good colour match is needed between the weld bead and the surface, AlSi5 should be avoided"
(AGA. Facts about aluminium welding, page 6)

When selecting the right filler rod.
AlSi5 = 4043


Link to download AGA's guide:
http://www.google.fi/url?sa=t&rct=j&q=& ... 8745,d.bGQ

[clayton47]

Tell me if this is correct- you are using ER-4043 filler metal?

My shop has one qualified process using this filler. The parameters are as follows:

Aluminum/aluminum based alloys, similar base metals (or base metal repair)
Base material type Aluminum castings
thickness range 0.060" - 0.500"
Process GTAW
All joint designs
Min preheat 60-deg F
Interpass temp 300-deg. F
Filler metal type MIL-4043, ER4043, or 4043
Torch shielding gas Argon/Helium
Shielding gas flow rate 20-40 cfm
Tungsten electrode dia. 1/8"
Filler metal size 3/32" dia.
Amperage range 60 - 200 AC

I don't know squat but to me the pictures suggest two possible factors, wrong shielding gas or interpass temperature.

I have a tube of 1/16 ER-4043 and then some 3/32 4043 I just picked up. Not sure what kind "exactly" it is.

[Tater]

clayton47,
That's the same thing.

[clayton47]

clayton47,
That's the same thing.

Well is didnt know exactly why it was listed like this in your post -

Filler metal type MIL-4043, ER4043, or 4043

please excuse my ignorance.

[Tater]

No ignorance!
Those are just the military or industrial specs. No difference in the filler material.

[Tater]

I harldy ever weld aluminum, let alone the nice stuff you are doing, so the ignorance is at my end

[clayton47]

Righton - I will keep working on the 4043 and try to improve! Thanks again for all the help and suggestions!

[GreinTime]

Personally, I have the opposite experience of @Braehill, and hate 5356 with a passion (even though it was all he would hand me when I was welding in the garage during my recuperation (he trolls me just for fun. He's messed up that way). I was having issues with Aluminum today, as both Jonathan and my Father can attest to because I talked to both of them about it at one point or another. Try, for S&G, turning your frequency down and see if it makes a difference. It's one fell swoop of the knob, and it will only take a few minutes