pre heat on aluminum smaw

Date 09-21-2014 14:49

Kent,

Aluminum SMAW. 1974. The job was repairing cracks on a rode hard beaten badly Aluminum Cattle hauler. I'm not sure if it was for perheat purposes or to soft work the hardend material back into shape before welding or welding on the patches but I remember thinking, this job sucks.
It heat did dry the urine, and toasted the poop to an easily brushed finish. And as you know, it did the job.

What I have learned since however, they work great for oxy-fuel fusion welding on smaller dirty Aluminum castings because the flux used is similar with an addition of a binder to hold it on the rod.

I'm trying to figure you out Kent. But if I had to guess, your a welder. An old welder.

By lo-hi

Date 09-22-2014 00:01

I too am an old welder . I also have repaired a bunch of aluminum cattle and horse trailers, usually at the dealers lot. Sometimes at the farm ,but then it got really stinky. There is a big difference a stock trailer used at auction and a 35 foot combo tack room show trailer. Usually in the driver, operator appearance. The only time I used pre-heat was to compensate for different thickness in cooler temps. The spool gun seemed to work the best.

By kcd616

Date 09-23-2014 06:25

thank you
all I ever wanted to be, was a welder
and the respect of my peers
sincerely
Kent

By Lawrence (*****)

Date 09-24-2014 22:09

Aluminum SMAW electrodes are better than in the old days for sure.

I don't recommend preheating aluminum unless an engineer above my paygrade compels me to...

If you are using SMAW it must be farm code work right?

You can expect it to be too cold at the start and too hot at the termination regardless of what you do. It's not every going to be pretty or consistent.

Now for the good news...... GTAW and GMAW

By kcd616

Date 09-25-2014 04:45

Lawrence
just trying to pass on knowledge and ideas
and your dead on about start and finish temps, and smaw is a b*tch for aluminum or stainless
(now a joke)
gtaw and gmaw, I clicked on that esab banner ad and that is some new fangled stuff :eek:

hope this helps
sincerely,
Kent
btw, got me beat, never have welded gtaw on dcep :cool:

By TimGary (****)

Date 03-11-2015 15:00

There's lot of different flavors of aluminum, each with it's own welding characteristics, but for general rules of thumb:

1. Cleanliness is next to Godliness. Use a stainless steel hand wire brush to remove the surface oxide, and follow up with an acetone wipe, immediately before welding to lessen lack of fusion and porosity defects.
2. Too much heat causes weak welds and cracks. Thick sections handle heat better (3/8" and above). Thin sections are very sensitive to heat input. Get in and get out quick while welding, don't preheat or do multiple passes if you can avoid it.
3. No autogeneous welding, becuase the weld will crack. Use the right filler metal to match the base metal.
4. Each thickness requires unique welding parameters. There's no one setting fits all thicknesses. Work out the right setting on scrap metal to avoid ruining parts, or better yet, follow a good WPS.
5. Never, ever, SMAW aluminum, unless you're a glutton for punishment, don't give a damn what it looks like after or how long the weld holds, and have a jackhammer handy for flux removal. (personal opinion, I'm sure there's someone out there who can SMAW AL just fine, but I've not met them yet).

Tim

By t_rod7018 (*)

Date 03-11-2015 16:30

Thanks, Tim. We definitely want to use GMAW because of high production rates. I'm currently writing a WPS for our product, but it's more involved than I thought it would be! I know what grade tubing we're using and filler metal, but they didn't teach us a lot about aluminum welding in school... out of the 2 and a half months we spent on MIG, we did one day on aluminum. I'm trying to breathe deep, not think about how much money I spent on school, and figure this out on my own, ha! Thanks for your advice!

Tori

By MRWeldSoCal (***)

Date 03-16-2015 21:47

Im not big on the acetone as a cleaner. I do a lot of aerospace inspection and we get a lot of people at least in x-ray that get more porosity and difficulty welding from acetone compared to Isopropyl alcohol. Acetone still leaves a film unless its followed up with a dry rag. When I was welding full time the difference was very clear in my own experience with it as well.

my .02 cents

Jordan

By Lawrence (*****)

Date 03-11-2015 15:17

No to the preheat :)

Assuming GTAW....... Just slightly adjust your torch angle to favor the thicker base metal

You can with practice make aluminum fillet welds, 1/16" plate to inch thick plate without any burn thru on the thinner member with zero pre-heat..

That is an extreme example, but it is totally doable. The difference between 1/8" and 3/16 is not enough to worry about at all.. Just a little practice is all you need.

By t_rod7018 (*)

Date 03-11-2015 16:00

Nope, boss wants us to MIG it. We're making aluminum truss frames and in high quantities, but safety is a huge huge huge deal for us. Does GMAW make a difference, or still no preheat?

Thanks,
Tori

By Jarhead1 (**)

Date 03-11-2015 16:45

Just did a job 6061 large aluminum channels 98" long 12" wide 1/2" thk. I must note...Extruded aluminum nice and clean.
GMAW Short circuit, AlcoTec 4043 - 3/64" wire.
Welded two channels together and a bunch of gussets and other components to the channels. Lots of weld.
Procedure - GMAW short circuit with a preheat temp of 400F. If we did not preheat there was no penetration and bead appearance was terrible to say the least.
Also, we were fighting warpage issues with weld/preheat with the long channels, multiple clamping did not help, intermittent welds did not help. There was a flatness tolerance I needed to hold.

I had to cut the channel 90's down to the flat which relieved all the stresses in the extruded channel.

What saved my ass was purchasing a Miller 350P pulsed MIG unit with push/pull gun. Like night and day.
Also someone else stated aluminum no matter which weld process used NEEDS TO BE CLEAN.

Thanks -

By t_rod7018 (*)

Date 03-11-2015 19:10

Thanks! We're using 6061-T6 tubes, I appreciate your feedback! I'm a little worried about not pre-heating because we can't do a back weld on most of the joints. Here's a link to kind of get a visual of what we're doing... aluminum truss frames for suspended scaffold work platforms.

http://www.gregbeeche.com/field_updates/Fort_Lee_Towers_Fort_Lee_NJ_USA_31_news.htm#!prettyPhoto%5bscreenshot5%5d/3/

Tori

By TimGary (****)

Date 03-11-2015 19:43

For safety and liability issues, you definately need to qualify your welding procedures and maintain a comprehensive quality assurance program.
Are you working to a code or standard, like AWS D1.2 or B2.1?
An aggravating thing about AL welding, especially on thinner sections, is that the weld joint has a tendency to be weaker than the connecting base metal, which has to be figured in to your design engineering.
For example, 6061-T6 has a tensile strength of at least 42 KSI, but the as welded tensile strength can be at least 24 KSI to meet AWS requirement.
Excess heat input causes a decrease in as welded tensile strength.
I've found that GMAW with 4043 filler can meet the 24 KSI requirement, but not as reliably as I would like, because it's highly dependant on Welder technique and control of heat input.
I'm having better luck with MAXAL's new 4943 filler metal.

Better get your ducks in a row.

Tim

By t_rod7018 (*)

Date 03-11-2015 20:20

Tim, we will NOT begin fabrication until the WPS is complete and we have all of the quality assurance stuff in place. We've learned from other people's mistakes there! I have the AWS D1.2 code, and the AWS Everyday Pocket Handbook for Gas Metal Arc Welding of Aluminum. The engineer I've been working with on this wants to use 5356 filler, because it has the same properties as the 6061 tube with the T6 finish. If we didn't use that finish, he would say to use 4043. Sure, it would be nice to not have to weld aluminum, but the extent to which we (successfully) use it in our designs is what sets us apart from our competitors.

Thanks for your feedback!
Tori

By ssbn727 (*****)

Date 03-12-2015 00:02 Edited 03-12-2015 00:33

Hi t_rod7018,

The T-6 designation has nothing at all to do with the finish... "T" = Temper, and in the case of "T-6" let's first understand what the letter "T" for Temper really means...

Basic Aluminum Heat Treatment Designations:
F - As Fabricated - No special control has been performed to the heat treatment or strain hardening after the shaping process such as casting, hot working, or cold working.
O - Annealed - This is the lowest strength, highest ductility temper
H - Strain Hardened - (applied to wrought products only) Used for products that have been strengthened by strain hardening, with or without subsequent heat treatment. The designation is followed by two or more numbers as discussed below.

W - Solution Heat Treated - This is seldom encountered because it is an unstable temper that applies only to alloys that spontaneously age at ambient temperature after heat treatment.
T - Solution Heat Treated - Used for products that have been strengthened by heat treatment, with or without subsequent strain hardening. The designation is followed by one or more numbers as discussed below... So basically the letters represent one form or another of heat treatment that was used to manufacture the aluminium alloy for a variety of applications... Now let's look @ the number designations that immediately follow the letter designations...

Heat Treating T Temper Codes

T1 - Cooled from an elevated temperature shaping process and naturally aged to a substantially stable condition.
T2 - Cooled from an elevated temperature shaping process, cold worked, and naturally aged to a substantially stable condition.
T3 - Solution heat treated, cold worked, and naturally aged to a substantially stable condition.
T4 - Solution heat treated, and naturally aged to a substantially stable condition.
T5 - Cooled from an elevated temperature shaping process then artificially aged.
T6 - Solution heat treated then artificially aged.
T7 - Solution heat treated then overaged/stabilized.
T8 - Solution heat treated, cold worked, then artificially aged.
T9 - Solution heat treated, artificially aged, then cold worked.
T10 - Cooled from an elevated temperature shaping process, cold worked, then artificially aged.

*Additional digits may be used after the first T temper digit to indicate subsequent stress relieving by processes such as stretching, compressing, or a combination...

So there you have it... I hope this explanation will help you better understand what "T-6" really means. :wink:

Lawrence, We're on the same page buddy and you assumed correctly. :grin:

Respectfully,
Henry

P.S. Here's another great site to learn more about aluminum welding and it's various alloys from AlcoTec, and offers Aluminium Welding Training as well as the Knowledge Center and ESAB University which covers many different topics related to Arc Welding in general and is not restricted to aluminium only... In this page are other links to the Knowledge Center and once there, you can also visit Aluminum Welding Questions and Answers:

http://www.alcotec.com/us/en/education/index.cfm

So you're Borinquen? Do you know what that means in the Taino language? Answer: Its an indigenous Taíno name, which means "Land of the Valiant Lord". Yo soy Americano! parents from DR & Cuba... Bendiciones... ENJOY! :grin:

By t_rod7018 (*)

Date 03-12-2015 20:55 Edited 03-12-2015 20:59

Thanks, Henry. The Alcotec website is very resourceful! I plan to meet with a local CWI to help me fill in the rest of the blanks on this WPS very soon.

...Dad's dad was born in Cuba (Camaguey), his mom born in Chile, my mother's family is straight off the boat from Sicily. We are loud, emotional, and love cooking and eating good food! :lol:

By ssbn727 (*****)

Date 03-12-2015 22:25

That is certainly a very interesting combination of cultures and very much alike my own heritage so the pleasure is all mine... :grin:

A woman after my own heart! :lol:

Where were you 25 years ago? :lol:

The AlcoTec site is an excellent resource like you mentioned but don't forget to read up on Frank Armao's articles from the industry magazines; The Fabricator and Practical Welding Today... besides, Frank is another one of Sicilian blood Capeche? Seriously, he's one of the best out there, and one can learn plenty just from reading his articles which are part of The fabricator's "Aluminum Workshop" I know, I usually spell it "Aluminium" because that's the way it was originally spelled so sue me!... :lol:

All the best to you and I'm glad the links were helpful. :cool:

Respectfully,
Henry

By t_rod7018 (*)

Date 03-13-2015 13:11

Haha, Henry, 25 years ago, I was learning how recognize letters and use a toilet! I will absolutely read up on Frank Armao's articles. I think when my boss asked me to write these WPS's, neither of us realized what it entailed. I like the challenge of the work though, I'm learning a lot. I graduated from welding school last summer, but they didn't teach us how to read blueprints or any metallurgy behind welding. Lucking because of the field I'm in, I had a good direction to get started. I really appreciate all of the help you and the other gentlemen have given me, I hope I can be as resourceful to others some day!

Tori

By kcd616

Date 03-12-2015 22:53

Tori,
your in albany, NY?
I am in between albany and utica
amish area
btw your getting some great advice from some of the best minds in welding
sincerely,
Kent

By t_rod7018 (*)

Date 03-13-2015 13:00

Kent,

I see that! I'm really enjoying reading through some other feeds you all have posted on, definitely learning a lot. The company I work for is in Waterford, it's a little north of Albany. Personally, I'm from the Saratoga area. Are you by Fultonville?

Thanks,
Tori

By TimGary (****)

Date 03-13-2015 22:47

Small world...
I spent about 7 years around Saratoga, Stillwater, Mechanicsville.
Do they still race homemade rafts down the Hudson River every Spring?

Tim Gary

By t_rod7018 (*)

Date 03-17-2015 17:38

Haha, that's great! I'm not sure if they do, we try to stay out of the Hudson. I don't think you want to swim in it or fish in it these days. Not sure if you've been around Saratoga lately, but it's getting bigger, a lot more commercial, small businesses are doing really well too.

By TimGary (****)

Date 03-17-2015 18:01

Harrumph....
Now I feel old, because I just realized the last time I was there was in 1978...
Back then, it was great fun every spring for enthusiastic young boys and girls to make homemade rafts, (I think the rule was to use only trash for building material) and race them several miles down the Hudson while it was running full with spring snow melt water. Most of the participants wouldn't finish the race, but there would be a lot of wrecked pieces of raft floating by.

Tim

By welderbrent (*****)

Date 03-17-2015 20:03

OOHH MMAANN, OOLLDD MMAANN!! You truly are dating yourself there Tim. You do realize, most of the participants on this forum weren't even born in 1978 :lol:

.

And here we are, already through school, married, and raising families by then. OUCH!

He Is In Control, Have a Great Day, OLD MAN GRANDPA Brent

By kcd616

Date 03-17-2015 11:10

Tori,
know Waterford well
owned an apartment building in Troy
I am southwest of Fultonvillle
go by there once a month for mine and the little womans doctors
We go through Fonda
but close enough :wink:

sincerely,
Kent

By Blaster (***)

Date 03-11-2015 19:48

Looks pretty important. I would make sure the every welder does plenty of mock ups that are torn apart and examined, and I would make sure they aren't leaving craters at the ends of the welds. I would also check for lengthwise cracks on the back side of the practice stuff. It is SO easy to put in bad aluminum MIG welds that look good on the surface.

By t_rod7018 (*)

Date 03-11-2015 20:34

Thanks, Blaster! I will note that we should do that in our in-house testing.

By Jarhead1 (**)

Date 03-12-2015 12:29

Tori,
I forgot to mention we eliminated preheat, 95% spatter by going with the Miller 350P very clean welds. Please, look into Fronius they make a really good aluminum machine but 3-times the price of the Blue machine.
Bothe machines can weld steel/SS as well.

By ssbn727 (*****)

Date 03-11-2015 20:01 Edited 03-12-2015 00:29

Hi Jarhead1,

What GMAW process variant & method of transfer did you use with the 4043 3/64" diameter filler? With the Miller 350P, was is short circuit or pulsed spray or globular? Did you use a starting tab to generate enough heat before you actually started depositing weld on to the joints? I ask this because what you describe isn't as clear to understand why you had to resort to preheat when it's not necessary @ that thickness unless the ambient temp was blow 32F... Tim basically covered the basics... Btw, there's a Aluminium filler numbered 4943 by Maxal and I think Hobart that comes really close to retaining most of the lost tensile strength due to welding on 6061-T6 as opposed to what you're left with after welding with 4043, so you might want to take a look at that filler I look forward to you response. :grin:

P.S. Check these articles out from Practical Welding Today which features Frank Armao who is one of the whose who of Aluminium welding From Lincoln Electric and read what he has to say about pre-heating aluminium:

http://www.thefabricator.com/article/aluminumwelding/aluminum-workshop-guidelines-for-preheating-t6

Here are @ least5 or 6 pages of articles listed covering exclusively Aluminium welding with practically all of the articles written by Frank Armao:

http://www.thefabricator.com/search/advanced?page=1&title=&author=&text=&content_type=article&publication=pwt&category=aluminumwelding

This is from MAXAL a data sheet on 4943 aluminium filler:

http://www.maxal.com/4943_datasheet.pdf

From Hobart:

http://www.hobartbrothers.com/news/153/523/Hobart-Brothers-Company-to-Showcase-New-Filler-Metals-at-FABTECH-2013.html

Here's a video of another Aluminium "Guru" or whose who named Tony Anderson from ITW welding NA (Miller) on the 4943 filler:

https://www.youtube.com/watch?v=XQHhrHXH0AQ

And finally, here's an article on the 4943 aluminium filler which is relatively new choice and how it has worked on the James Webb Space Telescope:

http://www.thefabricator.com/article/consumables/to-infinity-and-beyond-with-the-help-of-a-filler-metal

Last but not least, if one wants to retain most of the tensile strength that will be lost due to the welding, then the component/assembly/part must be post Weld Heat Treated, or else one will be stuck with a weldment that has lost almost half or more of it's material tensile strength making it weaker than prior to welding the aluminium... In other words; A hunk of junk or something new for a sculpture park! :eek:

Unless they weld to AWS D1.2? and can reliably keep @ least 24K tensile strength just as Tim pointed out earlier. :wink:

Respectfully,
Henry

By Lawrence (*****)

Date 03-11-2015 22:01

Didn't have time to read everything

But spray transfer should be just fine for 1/8 to 3/16 GMAWP even better. (I'm assuming Henry advocated this and I agree)

Both better and faster than GTAW as far as heat input and WPS qualification.

By Jarhead1 (**)

Date 03-12-2015 13:18

Hi Henry,
I have aluminum TIG certs in the past but not GMAW.
With the Miller 350P and Aluma-Pro Push-Pull Gun we are using pulsed spray mode (no-preheat) very little spatter and cleanup. AlcoTec 4043 MIG wire.
After fighting with the warping issue - I brought in some aluminum "experts" Larry S. (Miller) aluminum "Guru" Chicago area and
Don M from AirGas, both old school weld maniacs, if you know what I mean. Coming short of any expert trying to prevent warpage,
the next be thing was pulsed MIG, faster, cooler, still good penetration. I brought in 2-demos Millier and Fronius. Fronius had a lot more bells and whistles
as stated 3 x the price. Although, I layed down a couple beads that if I send pictures they look like a stack of nickles, or TIG welds pretty amazing technology.
Decided with the Blue machine $$$.
If you read many articles out there and for preheating aluminum just like other preheats there are multiple numbers out which makes it really confusing at times.

I will read your attached articles and will look into the Maxal filler.

Henry - Thank You for the information. I appreciate it.

By t_rod7018 (*)

Date 03-11-2015 22:10

Lawrence, I am asking your expertise... Would you make the weld 1/8" thick or 3/16" thick? An instructor at school said to make it 3/16" thick, however Section 2.4 of the D1.2 Code states that the effective weld shall not exceed the width of the part joined. So wouldn't that be 1/8" thick? I'm concerned about burning through the tubes.

By Lawrence (*****)

Date 03-11-2015 22:17

That question is for your engineer :)

Typically with thinner materials the "leg length" on a fillet weld is close to the thickness of the thinner member.

But aluminum makes a large deposit typically also.

Trials, Trials, Trials.

Getting the correct current/voltage parameters along with a very brisk travel speed will help keep the burn thru away and the fillet sizes as small as they can be engineered.

By Stringer (***)

Date 03-13-2015 12:12

Agree. Great info, Henry.

By 357max

Date 03-17-2015 14:20

Just as no preheat should be used in this application; be very careful with the interpass temperatures. Welds may have to be skipped from weld joint to weld joint. This will be proven with the heat input calculated for the WPS.