Aluminum welding repair info advice and tips needed. Lots of questions.

I've been getting more and more aluminum repair work in. So far I've been successful but I'm still paranoid about cracks and failures. I want to know that I'm doing these repairs to the best of my ability.

These repairs have been weighing heavy on my mind because I feel I don't know as much as I should about doing them.

Trying to learn as much as I can about aluminum repairs. If anybody has any resources they'd recommend I'd greatly appreciate it.

What are the best methods to identify cracks and where they end? I'm concerned that one day I may miss the end of a crack and have my repair fail in service. Hasn't happened yet but I know how crack prone aluminum can be especially around welds and repairs.

Normally what I'll do to a crack is wipe with acetone, hit it with a stainless hand brush(brushing in one direction) to remove the oxide layer, wipe again with acetone second separate "clean" stainless brush again wipe with acetone drill the ends and then V the crack out with a carbide burr or end mill. Is there a better way?

I try to do most repairs with a/c tig due to the cleaning action. Sometimes Ill do a cleaning pass before welding(Dynasty 400 and Syncrowave 350) but do have a 350p with push/pull and a dedicated aluminum millermatic 200 with custom 8' gun with a nylon liner and spool gun. Also have a spoolmatic 30a.

The only two filler metals I use and have are Nexal and Lincoln 4043/5356 superglaze.

Most repairs are on 5052/6061 or mystery stuff. I need to get better at identifying what specific type of aluminum I'm working with. Right now I rely on calling the manufacturer etc or just using 4043 .

I'll sometimes grind larger repairs or welds out with aluminum specific grinding wheels. I don't like the fact that I could just be impregnating the oxide layer into the base metal with powered wheels and abrasives. I was thinking about trying powered stainless steel end brushes for corners. Bad idea?

Is there a type of media I can blast to prep aluminum that won't impregnate in the surface or cause contamination and possible failure in the welds?

Can I use carbon arc gouging to remove welds? Been meaning to try it out but haven't had any scrap parts To try it on

Plasma gouging? How does plasma cutting affect the aluminum for welding? Is there any special prep needing after plasma cutting or gouging?

If it's a large or cast part I'll preheat in a oven or with the torch and allow it to cool slowly. Will do the same with parts contaminated with oil to burn off.

I try to preheat for at least my starts when using wire feed to avoid cold starts and incomplete fusion on starts.

What else can I be doing or do different?

Sounds like you've got the basic's covered. Dedicated stainless steel wire brush, AC Tig and acetone are the key things to use. Back when I had my machine shop we would use a dye penetrant to locate cracks on non-magnetic material. I think that the brand was Zyglow or something like that.

The folks on Weldingweb.com can provide a lot of assistance regarding aluminum.

I've always felt that TIG allowed me to make a better repair than MIG. MIG is used more for production work, but the arc control that you have with TIG will allow you to make a better repair IMO.

Blasting prep is not ideal for aluminum due to the potential to embed contaminants in the base material.

I've never tried carbon arc on aluminum - only steel. It is loud and messy, but a nice way to remove old welds.

Just watch out for the 2xxx and 7xxx series aluminium, they don't like to be welded.

Our aluminum guy once said the direction of travel can affect the potential for cracking and sometimes going two ways is better the just one.

You mentioned miller dynasty so this might help. For dirty aluminum I use very different settings than on new/clean aluminum. Don't be afraid to try different settings like sine, advance, triangle wave forms. Also the frequency setting can make a huge difference.

If I'm trying to burn out some porosity or contamination I set waveform to soft, EN around 260 EP around 220 66% 60 frequency. YMMV. If interested I can post some other settings with a short description of metal thickness, weld joints ect.

turnworks said:

You mentioned miller dynasty so this might help. For dirty aluminum I use very different settings than on new/clean aluminum. Don't be afraid to try different settings like sine, advance, triangle wave forms. Also the frequency setting can make a huge difference.

If I'm trying to burn out some porosity or contamination I set waveform to soft, EN around 260 EP around 220 66% 60 frequency. YMMV. If interested I can post some other settings with a short description of metal thickness, weld joints ect.

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That would be cool if you did that!

West-7 said:

I've been getting more and more aluminum repair work in. So far I've been successful but I'm still paranoid about cracks and failures. I want to know that I'm doing these repairs to the best of my ability.
These repairs have been weighing heavy on my mind because I feel I don't know as much as I should about doing them.
Trying to learn as much as I can about aluminum repairs. If anybody has any resources they'd recommend I'd greatly appreciate it.

What are the best methods to identify cracks and where they end? I'm concerned that one day I may miss the end of a crack and have my repair fail in service. Hasn't happened yet but I know how crack prone aluminum can be especially around welds and repairs.

Click to expand...

Identification of cracks is usually by a dye penetrant test.

West-7 said:

Normally what I'll do to a crack is wipe with acetone, hit it with a stainless hand brush(brushing in one direction) to remove the oxide layer, wipe again with acetone second separate "clean" stainless brush again wipe with acetone drill the ends and then V the crack out with a carbide burr or end mill. Is there a better way?

Click to expand...

Depends what the part is, thin parts with full penetration welds through the back side dont need much prep unless its filthy.
thicker then 1/8" and you need to groove the crack out till its almost 1/8" or until it cleans up.

West-7 said:

I try to do most repairs with a/c tig due to the cleaning action. Sometimes Ill do a cleaning pass before welding(Dynasty 400 and Syncrowave 350) but do have a 350p with push/pull and a dedicated aluminum millermatic 200 with custom 8' gun with a nylon liner and spool gun. Also have a spoolmatic 30a.

Click to expand...

Ive seen more aluminum failures in a spool gun then anything, push pull is better if there is pulse. but its too easy to lay filler on top that looks good but doesn't melt the base metal and the crack will just come back quickly.

West-7 said:

The only two filler metals I use and have are Nexal and Lincoln 4043/5356 superglaze.
Most repairs are on 5052/6061 or mystery stuff. I need to get better at identifying what specific type of aluminum I'm working with. Right now I rely on calling the manufacturer etc or just using 4043 .

I'll sometimes grind larger repairs or welds out with aluminum specific grinding wheels. I don't like the fact that I could just be impregnating the oxide layer into the base metal with powered wheels and abrasives. I was thinking about trying powered stainless steel end brushes for corners. Bad idea?

Click to expand...

brushes can be good and bad, good to clean the surface lightly, but bad as it shoves some impurities further into the surface.

West-7 said:

Is there a type of media I can blast to prep aluminum that won't impregnate in the surface or cause contamination and possible failure in the welds?

Click to expand...

Soda blasting, or dry ice.

West-7 said:

Can I use carbon arc gouging to remove welds? Been meaning to try it out but haven't had any scrap parts To try it on

Click to expand...

nope!

West-7 said:

Plasma gouging? How does plasma cutting affect the aluminum for welding? Is there any special prep needing after plasma cutting or gouging?

Click to expand...

it makes it one huge oxide mess....

West-7 said:

If it's a large or cast part I'll preheat in a oven or with the torch and allow it to cool slowly. Will do the same with parts contaminated with oil to burn off.

Click to expand...

all depends on the part. what do you concider large? cast doesn't always need pre heat. and it won't really burn anything off

West-7 said:

I try to preheat for at least my starts when using wire feed to avoid cold starts and incomplete fusion on starts.
What else can I be doing or do different?

Click to expand...

i would avoid wire feed unless it needs a massive amount of filler metal to be added.

ONLY thing i know many don't seem to do is fill in there craters at the end. that is the #1 leading cause of crack formations in a weld bead. leave a crater and it will 1000% chance crack and take out the whole bead.

Oak Lane Machine, it sounds like you have a good concept of what to do ...
You mentioned sometimes going over the crack 1 time to clean it.

Here's my process #1 Clean with acetone.
#2 If it's thin, go over the crack with a stainless wire wheel on a die grinder, if its 1/4" thick or thicker, vee groove with a aluminum carbide with bees wax to prevent clogging of the carbide.
#3 Remove bees wax with non chlorinated break cleaner.
#4 spray brake cleaner on your wire wheel to remove debris that may be on the wire wheel before using it to remove oxide off aluminum.
#5 Go over the crack to be welded with your amps 10% lower than what your going to weld at ( Using the torch to bring the crap to the surface ) then use the wire wheel to remove the contamination off the surface, go over it again with the torch and keep repeating this process until you have very little black coming to the top.
If you have access to both sides, do the same process on the other side.
#6 Depending on how bad it was, I may use brake cleaner to remove bees wax off carbide and then use the carbide lightly over the prepped area before picking up the torch and filler wire to finally begin the welding process.
This is what I do on critical parts that have been in oil soaked area.

To prevent cracked aluminum, make sure you're adding filler to the weld and not just fusing, while most metals are cool with fusing, aluminum is not, so add that filler !!!

All these settings are used with 1/8" 1.5% lanthanated tungsten(gold). Base metals 5052 or 6061. I won't list the max amps I normally set it a little high and just use the pedal to control the puddle size

Setting for thin to thick base metal where you are trying to keep the heat tight on a fillet joint that is close to the edge of the metal without rolling the edge.
Wave form: advanced
EN:175
EP: 135
% 75
Hz: 240
Pointed tungsten

Setting for most seam welds where I'm trying to get some extra penetration because the welds will be ground flush.
Wave form: soft
EN: 225
EP: 165
% 55
Hz: 100
Balled tungsten

Setting for all around general seam and fillet welds.
Wave form: soft
EN: 215
EP: 160
% 67
Hz: 175
Pointed tungsten

Setting for thicker base metal fillet joint using a rotary table.
Wave form: soft
EN: 265
EP: 175
% 75
Hz: 160
Balled tungsten

Setting for burning out porosity.
Wave form: soft
EN: 260
EP: 220
% 66
Hz: 60
Balled tungsten

As for the pointed vs balled tungsten. No matter the settings I always start with a pointed tip and let the tungsten do what it wants. I use 1/8" tungsten even at lower amps so how it balls up compared to 3/32 is much different.

Biggest repair jobs are pneumatic tanker trailers. They see 10-30 psi.

Failures on the seams of the tank, cracked flanges due to dissimilar metals and oxide jacking. Cracks at stress points on the tubes.

I can weld aluminum fairly well and I'm confident enough in my ability.

Is there some sort of set process or standard for aluminum pressure vessel welding?

Thanks for the replies everyone. It's greatly appreciated.

Does anybody have any recommendations for dye penetrant tests?

Are their any concerns with soda blasting? I'm excited to try this prep has been killing me on these larger neglected pneumatic tankers. Oxide layers thick and there's lots of bubblegum spool gun welds.

soda blasting is expensive.

if its just thick oxide, try a stainless wire wheel first, and one only used on aluminum. don't use too much pressure on it.

working on pressure tankers like that, hopefully the inside is clean also. if not it will suck all that junk in from the back side.

Portable Welder said:

Oak Lane Machine, it sounds like you have a good concept of what to do ...
You mentioned sometimes going over the crack 1 time to clean it.

Here's my process #1 Clean with acetone.
#2 If it's thin, go over the crack with a stainless wire wheel on a die grinder, if its 1/4" thick or thicker, vee groove with a aluminum carbide with bees wax to prevent clogging of the carbide.
#3 Remove bees wax with non chlorinated break cleaner.
#4 spray brake cleaner on your wire wheel to remove debris that may be on the wire wheel before using it to remove oxide off aluminum.
#5 Go over the crack to be welded with your amps 10% lower than what your going to weld at ( Using the torch to bring the crap to the surface ) then use the wire wheel to remove the contamination off the surface, go over it again with the torch and keep repeating this process until you have very little black coming to the top.
If you have access to both sides, do the same process on the other side.
#6 Depending on how bad it was, I may use brake cleaner to remove bees wax off carbide and then use the carbide lightly over the prepped area before picking up the torch and filler wire to finally begin the welding process.
This is what I do on critical parts that have been in oil soaked area.

To prevent cracked aluminum, make sure you're adding filler to the weld and not just fusing, while most metals are cool with fusing, aluminum is not, so add that filler !!!

Click to expand...

NEVER EVER USE BRAKE CLEANER ON WELDS OR WELD PREP!!!!!!
Some brake may be fine, some of it will kill you or leave you with long term neurological problems. I'm no chemist so I'm not taking any chances. What i do know is even the fumes from being used elsewhere in my shop react with welding process and produce noxious fumes and inclusions and crap in my weld.
1. clean with acetone
2. use an aluminum specific burr in your die grinder so it will not clog. wd40 seems to help and doesn't contaminate the weld if used on the tools.
3. use clean ss wire brush, they are cheap throw away or repurpose used ones. i don't clean them.
4. clean with acetone
5. procede as Portable Welder suggests for the rest of the process.

West-7 said:

Biggest repair jobs are pneumatic tanker trailers. They see 10-30 psi.

Failures on the seams of the tank, cracked flanges due to dissimilar metals and oxide jacking. Cracks at stress points on the tubes.

I can weld aluminum fairly well and I'm confident enough in my ability.

Is there some sort of set process or standard for aluminum pressure vessel welding?

View attachment 372556

Click to expand...

A pressure vessel welding certification at the very least. That thing is just a shiny bomb.

Most repairs are on 5052/6061 or mystery stuff. I need to get better at identifying what specific type of aluminum I'm working with. Right now I rely on calling the manufacturer etc or just using 4043 .

Click to expand...

Welding 5052 with 4043 is a bad idea. It makes a very weak and brittle weld. Go read everything you can on the Alcotec website.
Get an old file and grind a blunt, but very sharp bevel on the end and use it as a scraper for prep. It's like a one tooth file, and will make quick work of nasty hydrated oxide and 6061.
Carbide burrs with some belt grease to prevent gumming up the teeth will remove material quickly. I've used plasma gouging in certain circumstances, but you still have to grind away the cut edge. Plasma cutting on 6xxx alloys is not recommended for load bearing applications unless you mill away .125" or so from the cut edge. That's from the D1.2 structural code (AWS).
If you have a lot of weld to grind and blend, get some Formax belt grease and a Dynafile. The belt grease will drastically increase the rate of removal when using abrasive belts. It changed my life.

We had a job seam welding eight-foot dia. satellite dishes. We got so busy we outsourced to a shop out of state. the parts had to be spun after welding. The welds did not hold. We had an 8-foot diameter Aluminum sheet coming apart on the spinning lathe. I took trip up to the company to see if we could resolve the issue. The parts were not clean, full of oil and the seamer was soaked in oil. What we had was Hydrogen Embrittlement from the oil. They cleaned up their act and had no more problems. Isopropyl Alcohol will clean the part as well as Acetone, It is a little safer chemical for cleaning and is easily available. A key to good Aluminum welds is "cleanliness is next to godliness". And you have it covered.
Roger

Dye penetrant for crack checking.

I spent some time in an aluminium fabrication place once and at every station they had angle grinders with a blade on it that was literally a miniaturised skill saw blade, with guard obviously. I accept no excuses from those guys who remove guards on their angle grinders. I value my fingers too much.