[dunkster]

yeah, hopefully he stumbles across this

[Otto Nobedder]

I'd have to get up to speed on this before I could attempt to comment. I can tell you about corrosion stress cracking in austenitic stainless until you're sick of my voice, but I was not aware of any similar phenomenon in aluminum.

I will be doing a little digging over the next several days, starting with the information already posted here.

I use 5356 a lot, particularly on 60xx alloys, but in either ambient temp or cryogenic applications, so the 150* thing would not have applied to me if I had been aware of it.

Steve S

[Turbo]

5554.JPG (58.14 KiB) Viewed 1655 times

I like 5554. It is what you should use for production, but from what I have been told it will take years or decades for the 5356 joint to fail from boiling temps.

[BigD]

Yeah, I got a hold of an aluminum expert from a very respectable company but I've been waiting for his express permission before I share his words verbatim. But to paraphrase, he said it takes hundreds and possibly thousands of hours of exposure to stress in a corrosive environment and high heat before this is a concern, in other words, not a concern for my application.

I still hogged out and rewelded my thermostat housing because I'm a loser.

tstathousing.jpg (82.65 KiB) Viewed 1651 times

[dunkster]

Yeah, I got a hold of an aluminum expert from a very respectable company but I've been waiting for his express permission before I share his words verbatim. But to paraphrase, he said it takes hundreds and possibly thousands of hours of exposure to stress in a corrosive environment and high heat before this is a concern, in other words, not a concern for my application.

I still hogged out and rewelded my thermostat housing because I'm a loser.

What filler did you settle on BigD?

[BigD]

Still waiting on the 4943 so I just refilled it with 4043

[dunkster]

Still waiting on the 4943 so I just refilled it with 4043

Thanks.

Was it you're conclusion that 4943 is best for cooling system components or is 4043 acceptable as well?

[BigD]

Thanks.

Was it you're conclusion that 4943 is best for cooling system components or is 4043 acceptable as well?

Anything that's not high Mg filler (ie 5xxx) should be fine (and the 5356 appears to be fine in reality, just not ideal), just 4943 seems to have all of the desirable properties of 4043 and strength approaching the 5356. So I want to make it my new go-to.

[Olivero]

Thanks.

Was it you're conclusion that 4943 is best for cooling system components or is 4043 acceptable as well?

Anything that's not high Mg filler (ie 5xxx) should be fine (and the 5356 appears to be fine in reality, just not ideal), just 4943 seems to have all of the desirable properties of 4043 and strength approaching the 5356. So I want to make it my new go-to.

Yeah, its amazing stuff, I got 10 pnds of it on the shelf, phased out my 4043 completely but I still keep 5356 on the shelf for 6061 alloy.

I find it works well on cast aluminum as well.

[Otto Nobedder]

LSCustoms sent me about 5# of Hobart 4943 to try (thanks, again!), and I'm sold on it, as well. The compatibility chart says it covers everything from 11XX to 60XX. Just yesterday I repaired a cast part with it, with great success. It wets out very nicely and has a smooth finish. I've yet to see that frosty finish I sometimes get with 4043, so it's great for visible welds that won't be painted.

Like Olivero, I'm keeping the 5356 for 6061, as the applications where I weld 6061 can't afford any sacrifice in strength and I've not done any testing to compare the two, but for everything else 4943 is likely to be my "go-to".

On a side note, has anyone tried 4047 on dirty castings, like Jody did in one of his videos? I rarely weld cast aluminum, but when I do it's rarely clean. (Yesterday was the exception... The part was nearly new and spotless clean.)

Steve S

[LtBadd]

and I'm sold on it, as well.

The compatibility chart says it covers everything from 11XX to 60XX.

Like Olivero, I'm keeping the 5356 for 6061, as the applications where I weld 6061 can't afford any sacrifice in strength

Steve S

It was my understanding that 4943 is stronger then 4043 for welds on 6061? YES/NO

[Otto Nobedder]

It was my understanding that 4943 is stronger then 4043 for welds on 6061? YES/NO

Yes, that is my understanding, as well. But, is it as strong as 5356, when used on 6061? I don't know enough about metallurgy to predict this, which is why I continue to use 5356 for this instance.

Steve S

[BigD]

Yeah from what I read, 5356 is still ultimately stronger than 4943

[Arno]

If a parts needs to be (color) anodized after welding then I suspect 4943 may not be the best, just like 4043. 5356 likely to give a better end result color match with the base material.

Unless you need to anodize black or dark grey, then it's fine as 4043 turns black anyway

Bye, Arno.

[Olivero]

and I'm sold on it, as well.

The compatibility chart says it covers everything from 11XX to 60XX.

Like Olivero, I'm keeping the 5356 for 6061, as the applications where I weld 6061 can't afford any sacrifice in strength

Steve S

It was my understanding that 4943 is stronger then 4043 for welds on 6061? YES/NO

From what I see on my chart here, look in the red box, 5356 is stronger when joining 6xxx alloys than 4943,

Filler chart.png (277.87 KiB) Viewed 1629 times

I am sure 4943 could be used and it might be better in some cases but based on performance in terms of strength and hardcoreness alone; looks like 5356.

[BigD]

I got permission to share the gentleman's opinion publicly so here is what he said.

Frank G. Armao
Director, Aluminum Technology
Lincoln Electric

In order to get stress corrosion cracking (SCC), you need 3 things. First you need a susceptible microstructure. You get that when you expose any aluminum alloy containing more than 3% Magnesium t(5356 has 5%Mg) to temperatures higher than 150 degrees F for long times – 100s or 1000s of hours as I said. Second, you need a stress. Usually the residual stresses around a weld are more than enough. Last, you need an electrolyte – salt water is the worst, but any impure water will also work and cause SCC. If you take any of those 3 factors away, you won’t get SCC.

So if you only expose the 5356 to atmosphere (not to engine coolant), you won’t get SCC.

SCC is actually fairly common. You usually find in marine environments. The US Navy, for instance, is having a problem right now with a class of aluminum hulled ships that are cracking where the engine exhaust pipes come out of the 5083 aluminum hull. In 2016, I encountered a problem on a large aluminum hulled yacht where the hull was cracking from SCC. Why? Because the builder routed the engine exhaust piping right up against the 5083 hull. The solution was easy. Fix the cracks and move the exhaust piping inboard a bit so it didn’t get the hull hot.

[Olivero]

Interesting, well there you go.