Aluminum weld destructive testing??

[ProctorSilex]

I am learning how to TIG aluminum. I moved on from a plate of beads to corner joints. I am welding two 4"x1"x1/8" bars together along the length then beating on the weld with a hammer (corner of joint pointing up). The bars bend lengthwise along their middles first. After it bends half way down, the weld fails right down the center. Does anyone here know how TIG welded aluminum joints should fail?
I did a cross section cut of one piece which ended up looking like it had complete penetration but the jig saw blade could have smeared it. I can post a video and pictures later this week. I have been searching the interwebz and found nothing specifically about aluminum testing. I thought I would check here first before joining a welding forum just for this question.
By the way, the aluminum work pieces are just run of the mill stock (nothing fancy). The filler metal is 4043.

[helowrench]

The base metal should fail before the weld does.

[Piledriver]

Things to consider:
The bars etc are likely 6061T6.
The weld area being annealed probably doesn't help.
(heat treating aluminum is sort of bassackwards from steel alloys, rapid cooling leaves Al dead soft)

[Ol'fogasaurus]

http://www.ehow.com/how_8250976_heat-tr ... welds.html

http://www.thefabricator.com/article/al ... n-for-6061

Not all AL is wieldable and some isn't readily heat treatable after working. 6061 is a very common AL and is available in several heat treats ranging from Annealed (-0) to -T6 or above (maybe). You really need to know the alloy you are dealing with or it is potluck on what you are doing.

http://www.welding-advisers.com/Welding-aluminum.html

http://www.thefabricator.com/article/al ... num-alloys

I hope this helps. It is getting longer and longer since I was very familiar with working with AL sheet, plate, casting or ???

Lee

[ProctorSilex]

I will check on the alloy and tempering from the supplier. The bar I have been using for the corner testing is from Home Depot and I think it did have 6061 printed on it. The HD and other hardware store stock is pretty expensive. I only got it for testing because I did not get enough when I was at the supplier which has unfriendly hours for the hobbyist :/
Thanks for the input. I will update.

[Ol'fogasaurus]

http://en.wikipedia.org/wiki/Aluminium_alloy

Look down the chart for AL alloys used in castings; the table above is also a good source for information.

http://www.ehow.com/how_8045809_weld-al ... sting.html

http://www.weldingtipsandtricks.com/cas ... lding.html

http://www.aws.org/wj/supplement/04-2005-CAO-s.pdf

Some tips on welding AL alloy castings.

Its like deja vu all over again (http://en.wikipedia.org/wiki/Yogi_Berra At the bottom are Yogi-isms). Its been probably well over 45 years since I got into this kind of research on AL alloys... sum fun! Do some searches on welding AL alloys especially casting and/or forgings as there is a lot more out there than I have posted.

Gotta make you a better person after you figure it out.

Lee

[falcor]

and remember most aluminium grades doesnt have the ductility of steel so they cant take as much deformation as steel does before it starts to break....

[aircooledtechguy]

Any mechanical method of cutting the joint apart will smear the aluminum and mask what you are looking for.

Typically, when I worked as a non-destructive tester, I would see cracks form at the edge of a weld in the base metal. If the aluminum had been sanded, peened, media (glass bead) blasted, cut, etc. I would first need to acid etch the inspection area before I could do any dye penetrant inspections. Either that or I would have to do an eddy current inspection.

A simple penetrant inspection will tell you about all you can hope to find without sending parts to a lab for analysis. In my experience, most of the flaws in an aluminum weld will be inside the weld and not visible without an X-ray (which is how I had to test weld test plates).

[ProctorSilex]

The supplier has no idea. I don't know how that's possible
I will look over the pieces tonight for stamps like the HD piece had. I doubt that it is unweldable or fancy.
I'll look more closely for cracks like aircooledtechguy mentioned. Time to get a magnifying glass. Maybe I could use some of those magnifying spectacles from the drug store for welding and inspection

[fusername]

Mostly related to steel, but turned this up looking for info
http://www.g-w.com/pdf/sampchap/9781605257938_ch18.pdf

[ProctorSilex]

fusername, thanks. I will take a look at that after recovering from a night of insomnia and lost time.

Update: I manged to get two strong welds yesterday: one butt and one outside corner. I was looking at the failed welds and scratching my head all week. Some of them clearly did not penetrate completely while others looked complete, but they all failed identically: down the center of the weld. I could see the flat edge of the parent bar in one of the last failed welds. I think that the puddle was running down between the joint as it appeared during the welding, but the alumina (the oxide) was not breaking up enough, which gave the appearance of full penetration on some of the welds. Yesterday, I was more aggressive with the pedal and let the puddle sink more than before. Of course, the higher current means more difficulty with burning through which has been hard enough already. I bent the pieces in a vise with wide jaw pliers. I even beat the butt joint with a hammer to bend it some more. Neither have broken anywhere yet. Pictures to come.

[Ol'fogasaurus]

The supplier has no idea. I don't know how that's possible Very possibly true. Re-sellers or their employies don't always know or care... sad but true
I will look over the pieces tonight for stamps like the HD piece had. I doubt that it is unweldable or fancy.
I'll look more closely for cracks like aircooledtechguy mentioned. Time to get a magnifying glass. Maybe I could use some of those magnifying spectacles from the drug store for welding and inspection

I have to weld with reading glasses but your view is limited especially with store bought glasses. The center of vision is an average and not as good for everyone as custom "readers" would be. Inspection glasses might be as close as in the 400 to 600 range to get to see the small details. Look for a table mounting unit with a large magnifying glass so that you can hold things in your hands to move the object around to inspect it. With the table clamp mount type of mag glass the viewing area is usually larger (spend the money to get a good one if you really think you need to do this) allowing for better viewing for inspection.

I did a search and the ones on eBay are smaller. Mine, if I remember correctly, has a 4" or 6" glass and a circular florescent bulb. I think the arms are close to 2' long and the base swivels allowing some larger pieces to be slid under. Good for picking metal slivers out of your hands also.

Lee

[ProctorSilex]

Welds shown with start on left.

Butt: top. Outer edges are from another practice weld that failed.


Butt: bottom. Full penetration most of the weld. Welded with no gap. After bend test and hammering.


Butt: bent and hammered


Corner: top. Burn through at end.


Corner: bottom. Started from left. Smudges from Home Depot's infernal indelible price sticker.


Corner: bend test. Burnt through end.


Tried to get magnified picture of failed weld edge (outside edges facing camera) (similar photo to the butt top view above). Penetration was incomplete because oxide had not been completely broken.


I am excited to feel like I am moving forward with this project again!

By the way, I picked up some 1.25x glasses from Dollar General. They were the only ones that had a focal length more than a foot from my face! The focus is about 1/2-3/4 of an arm's length. I did not notice a difference while welding with them, but I suddenly had success while wearing them. Key to TIG welding, functional, or coincidence? Time will tell I hope.

I have not seen any cracks in my aluminium welds yet, except for crater cracks at the ends on my plate of beads.

[Ol'fogasaurus]

My apology, I have to wear 275s to read so I gave you high numbers . I'm too used to those ranges of magnification so I gave them to you who it sounds like still have good eyes. One of the things I have learned is you have to see what you are doing but at the same time take care of the inhalation of gasses too.

I also try to use a heat sink at the start and end of the weld to absorb heat and stop melting (MIG). With TIG I think you use pedal power to do this.

With box store materials I have found that quite often they have no clue as to what they are carrying. I have been given false information many times so I only use them when I have no choice.

Lee

[ProctorSilex]

My apology, I have to wear 275s to read so I gave you high numbers . I'm too used to those ranges of magnification so I gave them to you who it sounds like still have good eyes. One of the things I have learned is you have to see what you are doing but at the same time take care of the inhalation of gasses too.

I also try to use a heat sink at the start and end of the weld to absorb heat and stop melting (MIG). With TIG I think you use pedal power to do this.

With box store materials I have found that quite often they have no clue as to what they are carrying. I have been given false information many times so I only use them when I have no choice.

Lee

No worries. I generally disregard specifics and look for generalities in people's advice.

I am afeard of losing the ability to breathe comfortably so I started welding with masks like these. But they fog up the mask and only do a seemingly minimal job of filtration. I recently acquired this mask with a downward exhaust along with these filters that are rated for welding. The helmet no longer fogs and I don't smell anything (if that's some indication of filtration).

Yes, the TIG pedal is meant to give control to prevent burn through and such, but it is still hard! It probably does not help that mine is a "cheap" Chinese welder. A pretty nice welder for the hobbyist, but definitely not the Lotus Exige or even the Mazda Miata of the welding world.
A problem I have with the pedal is that although I can drop off the current to not burn through, there is a small window of time and current in which the puddle needs to stay hot enough long enough with the cleaning action to fuse at the end without burning through. In the photo of the bottom side of the corner weld, you can see an arse shaped crease at the start of the weld (left). Looking at it from that end you can see that although the base metal was starting to collapse around it the oxide was still holding its own thereby preventing complete fusion. Practice, I guess!



Thanks for the info. One of the Youtube welders (Mr. TIG from weld.com, I think) said that aluminum welders grab every piece of copper they can get to use as heat sinks and backing for aluminum welding. Been keeping an eye out for copper! I also picked up some thick steel plates.

The practice bar was from Home Depot, but the ton of metal I got for the actual project came from a local metal supplier. The supplier should really know what the heck they are selling!