Cracks in Aluminum Weld

[Broccoli1]

I sanded and then SS wire brushed it. The edges are plasma cut, so that probably didn't help.

"Plasma Arc Cutting, Beveling, and Gouging:

· This process has some limitations and must be carefully controlled. If it is used, it requires the power source to be set (DCEN) along with the use of small orifices to gain high velocity and concentrated heat. Heat affected zones will be crack prone particularly for 2XXX, 6XXX, and 7XXX series alloys and will require 1/8 inch or more of mechanical surface removal before welding. Series 1XXX, 3XXX, and 5XXX alloys are not as crack prone and can generally be welded as cut by this process."

From the Link

[Blackbird455]

I was gonna say that too. Unless you are using a shielding gas while plasma cutting, you have to remove most of the HAZ because of the high levels of oxidization that occur. Even when you use shielding gas vs. comp air, the oxidization penetrates more than you would think. Also, I would use a 5356 filler on a 50xx series aluminum. It also looks like you might need to use a little more balance to clean the weld better.

What machine are you using? What tungsten? Balled or pointed? Pulse?

[jpmassey]

I was gonna say that too. Unless you are using a shielding gas while plasma cutting, you have to remove most of the HAZ because of the high levels of oxidization that occur. Even when you use shielding gas vs. comp air, the oxidization penetrates more than you would think. Also, I would use a 5356 filler on a 50xx series aluminum. It also looks like you might need to use a little more balance to clean the weld better.

What machine are you using? What tungsten? Balled or pointed? Pulse?

Syncrowave 250dx
I believe I was using pointed 2% thoriated.
No pulse option.

[FATFAB]

The picture appears to have very little filler and a bunch of contamination.





Griff

Where?

1234567890

[Blackbird455]

See it now?

The little black pepper looking flakes that float on the top of the puddle turn into stuff that looks like that. Also notice that the white "flash" on the outside of the bead is narrow, meaning only a small amount of DCEN in the cycle, balance adjustment might fix it, but like was said before, if it was plasma cut, there is alot of oxide present, and it needs to be removed before welding.

[griff01]

Where?

1234567890

Open eyes, look in picture.

Griff

[griff01]

See it now?

The little black pepper looking flakes that float on the top of the puddle turn into stuff that looks like that. Also notice that the white "flash" on the outside of the bead is narrow, meaning only a small amount of DCEN in the cycle, balance adjustment might fix it, but like was said before, if it was plasma cut, there is alot of oxide present, and it needs to be removed before welding.

Thanks for the back-up there blackbird.

Griff

[griff01]

Hmmm....I might be watching for enough penetration. This is my 1st major AL welding project, so I was excited just not to blow a 1/2" hole in it.

I didn't think that preheating was required on such thin material?

Pre-heat is not required if you have enough machine.

"Hot cracking" ( that is what this crack is) is influenced by only three things:
1. base alloy chemistry
2. filler alloy
3. joint design

1 and 2 are self explanatory. 3 also includes amount of filler put into the joint.


Griff

[griff01]

Syncrowave 250dx
I believe I was using pointed 2% thoriated.
No pulse option.

I just saw where you have a SyncroWave 250. That is plenty of machine for .125 and no pre-heat.
5356 is the "correct" filler for the 5052 base but the 4043 "should" have been ok due to its higher silicon content. That is out of the "book" .

Griff

[Steve]

Looks like more filler is needed to offset the undercut.