MIG welding 5086 with 5556 filler 1

[DAVIDSTECKER]

We are in the process of qualifying a weld procedure for 5086 Aluminum using 5556 filler wire and we are getting lots of porosity using the MIG process.
The plate is 1/2" thick, the weld joint is a "V" groove, wire is 3/64 (.047) diameter.
We have success with TIG on the same base material.
We've tried 3 different machines, 3 gas bottles and 2 different spools of wire so far.
This is for a Military standard and X-ray is part of the testing.
This is my first experience for aluminum weld specs and this is not actually my project but when doing some research on the 3/64th wire, one thing that I came across is that 3/64th wire is not for this thick of material.
The data I found leads me to 1/16th wire for this thick of plate.
I have a group of experienced welders that say the 3/64 is useable for the 1/2" plate, but have yet to produce a passable weld.
Looking for thoughts on wire size and insight to how this type of defect was resolved.
Best regards, David

 

[Ron]

Are you getting defects other than porosity? What shielding gas are you using and what are your machine settings?

 

[gtaw]

Break open a sample so you can examine the porosity. If the porosity is silver, the problem is hydrogen. If it isn't silver, the problem lies elsewhere.

There are numerous sources of porosity. A few are listed below in no special order:
1) hydrates on the surface of the aluminum.
2) oils from handling the material with bare hands
3) grease/oils/hydrocarbons from insufficient precleaning
4) hydrocarbons from "bee's wax" used to keep tools from loading up while working the aluminum
5) oils, hydrocarbons, moisture from air tools. Air tools should exhaust toward the rear and use a short pig tail to ensure the exhaust doesn't contaminate the base metal
6) possible surface contamination on the filler metal from drawing lubricants that were not removed before packaging
7) use of "old" filler metal that has been exposed to the shop environment and has been contaminated or if the shop is experiencing humid conditions, has hydrates on the surface from long term exposure
8) tools used to prepare the base metal/groove were not cleaned prior to use
9) tools used for interpass cleaning were not cleaned periodically during use.
10) shielding gas entrained moisture from the air due to a loose connection or old hoses (this usually results in discolored porosity from the air more than the moisture)


Best regards - Al

 

[kingnero]

In addition to what already has been said, using 3/64 (1.2 mm) wire is certainly no problem.

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[gtaw]

The larger the electrode diameter, the better. For a given volume, the larger diameter has less surface area, thus less surface to collect contaminates. I recommend using the largest diameter the equipment will handle. Make sure the welders are in spray transfer mode.

Best regards - Al

 

[TimSchrader2]

Hello
I Have a PQR here that we did a few years ago. For 5083 with ER 5183 filler @ 1/16Diamter.
tested 1" pl, 60deg bevel with back up plate.
Argon 25% Helium75% 75CFH
GMAW 300amps 28volts 60IPM Pulse arc took 20 passes. Weave bead.

The 60 IPM does look real slow. we usually use 300IPM for standard welds. I recall we had some issues passing the bend test. So that may have been what was needed.

Pre heat 250F

Cleaning: Sanding and acetone
Inter pass clean: wire brush
5083 should be similiar. Group no 25.

Not sure why the WS D1.2 or any other does not have a ref for various PQR's. I looked and could not find any back when this was done. Maybe someone has published one by now.

Good luck

 

[DAVIDSTECKER]

First, thanks for all the helpful feed back.
Currently we are using Washington Alloy's 5556 wire.
They've run 100% Argon and also 75/25 Argon/Helium.
Voltage is about 24 VDC, amps have been running 120-160.
When I first got involved they have the wire feed around 540 IPM.
They been all over the place since then.
I was looking at a backing weld they had cut off and I did see 2 large gas pockets that were as shiny and silvery as a ball bearing when I looked through a loupe.
The entire bead looked and felt like a course round diamond file.
The follow on passes were checked with Die penetrant and the indications were usually single spots and while not clustered they would be localized in an areas and on the outer edges of the bead.
The weld prep was done on the mill.
They did do a very good job for the cleaning. Lots of Acetone and Scotch Brite wheels.
The gap for the root pass have varied for 1/8-1/16"
Root pass has been copper backed with a groove cut in it and also no backing.
I think that I am going to press for the larger diameter wire a little harder and check closer for more signs and sources of Hydrogen as the next steps forward.
Again, Thank you for your input.
Best regards, David

 

[gtaw]

I do not recommend "Scotch-Brit" pads for preparing or interpass cleaning aluminum. Any abrasive media containing aluminum oxide has the potential of embedding aluminum oxide into the surface of the base metal. It is best to use stainless brushes, Vixen files, rotary files, etc. to prepare and to clean the aluminum. Do not use power brushes because they can burnish the surface of the aluminum. Make sure the tools are cleaned before use and during use to ensure they are clean.

Clean, clean, clean. I prefer to use acetone for the initial cleaning and 90% isopropyl alcohol for the final preweld cleaning.



Best regards - Al

 

[DAVIDSTECKER]

Thanks gtaw, I'll look into it.
We do go through a lot of 6061 building ships accommodation ladders and gangways.
They MIG and TIG with no issues using the same tools and supplies but it seems that just because it works for one material doesn't mean it will work on different material.
I'm not sure if this is going to go forward in the near future, they fell back to TIG for the project and sent the test coupons in with a new PQR.
Best regards, David