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Up Topic Welding Industry / Technical Discussions / High Frequency Cracking 6061
- - By MRWeldSoCal (***) Date 06-06-2014 17:58
A customer came into our shop today asking questions about cracking issues realted to some 6061 tubes. 

350 syncorwave
2% ceriated 1/8" tungsten
60 Htz
250 pre heat

and a fairly thick flange.

Welds appear cold looking, problem is he is getting cracking where the HF cleans too far from the weld.  Instead of a consistant HF line at the edge of the weld there are spots where it widens and there is cracking there.  It is in every spot where the HF gets too wide.

He said he had a Dynasy available so I told him:
Lighten up your preheat
Use pure GREEN tungsten
Turn up the Hertz to fine tune in the HF so it doesnt wander

He didnt give me an inches per minute, but its a smaller 6" pipe to flange.

Anyone else have anything to ADD on this fine FRIDAY?


Parent - - By aevald (*****) Date 06-06-2014 18:12
Hello Jordan, if he is using a Dynasty: don't use the pure tungsten. Check the literature and manual for that machine and it specifically refers to NOT using pure tungsten. As to the cracking line regarding HF cleaning: HF is not the provider of cleaning, the amount, amplitude, and other characteristics of DCRP in the AC sine wave is. As you increase the duration of the AC cycle on the DCRP side, cleaning increases, if you are also able to increase the amperage independently of the other side of the cycle(DCSP) you will likely have an increase in the boundaries of the arc cleaning area.

The cracking sounds as if it might be related to too rapid of a cool of the weld metal, creating stress cracking from this cooling(if he is using 5356 it is possible that the alloy is strong enough that the parent metal yields before the filler does as cooling is taking place). He may be better off with a lesser HZ setting to increase the arc column size and providing for a more expanded heating of the weld zone as opposed to a localized one from a higher HZ setting, this information would relate to use of the Dynasty and not the Syncrowave. Doing this would provide for a slower cooling rate as the welding is progressing and possible aid with the "quick freeze, crack possibility). I am sure others will have additional information to contribute on this. Good luck and best regards, Allan
Parent - - By MRWeldSoCal (***) Date 06-06-2014 18:42
The cracking is only within the HF line, doesnt step out side that boundry.  If we had a straight weld, the places where the HF widens, cracks only there and they are in a clean shine area, no the dull base metal.  I wasnt able to get any photos, if it was cooling wouldnt it crack all over and not in these particular spots?

Parent - - By aevald (*****) Date 06-06-2014 20:35
Hello again Jordan, with the GTAW process you have a lot more operator controlled variables than with most other processes. Consider travel speed, you can dwell on a spot without showing forward progression or adding filler, this can influence "soak"(area heating), at the same time you could vary amperage levels if you were using a pedal. This simple scenario would likely introduce different amounts of heating or heat affected zone size. Addition of filler at different intervals or rates could additionally affect the amount of heat being inputted due to the heat-sink effect from the filler metal coming into contact with the puddle/arc and in the case of the puddle drawing some of the energy from the weld pool to melt the filler and essentially cool or in some cases "freeze" the weld puddle. Just a few more items for you to consider. Best regards, Allan
Parent - By MRWeldSoCal (***) Date 06-06-2014 21:03
Thank you for the information and help!

Parent - By electrode (***) Date 06-07-2014 15:56 Edited 06-07-2014 16:13

you've posted something a while back, questioning the mechanism which you obviously estimated in charge of "cleaning" the aluminium surface:

And, as also been done here along this thread; i.e.:

you have obtained profound response at that time:

Basically it was explained in all responses that 'HF' (which I suppose denoting 'High Frequency') is not the "cleaning-"mechanism driving force.
And after all the replies, and despite those explanations given in this thread, you nonetheless continue to speak of a 'HF line' which again is confusing to me. No offence. Just trying to understand if I am missing something here.


Maybe this highly interesting thread can also prove helpful to you:

I suspect especially this:

may show something similar to that described by yourself.

Parent - By 357max (***) Date 06-07-2014 18:32
It would be suggested to decrease the HAZ by limiting the input and which may be accomplished with a sharpened tungsten with a radiused end without balling. Set the AC Balance control at maximum which should be 68% with the Syncrowave and the Dynasty can be moved towards 75% time at negative. The Syncrowave has only a 60 hertz output the Dynasty may be varied to 120 - 180 hertz which provides a more focused arc. BTW when AC (sinusoidal or squarewave) is shown on an oscilloscope there is a zero ( 0 ) line. When the wave is above the zero line the output is positive and when the wave is below zero it is negative. It is still AC not DC ~ that occurs when it is rectified. High frequency - High voltage arc starter adjustment only aids in starting and stabilizing. It has no affect on penetration or oxide cleaning. Oxide Cleaning is a result of mechanical, chemical and the positive side of the sine wave. If the aluminum has been thoroughly cleaned mechanically, minimum time at positive is necessary. 
Assuming that thick sections are being welded using a multiple pass technique it would be suggested to allow cooling between passes
Parent - - By electrode (***) Date 06-09-2014 09:42

At another note in connection to your "Good books for weld science" post - and again without any offence intended.

Abbreviations/denotations appear easy to use, since naturally the author is fully aware of their meaning.
However, when communicating/sharing with others they sometimes might impede the reader's comprehension.

Not that 'HF' was that difficult to interpret (I hope though it means 'High Frequency') but, as you are also searching for scientific welding books, just a friendly cue. You may find in these "good books for weld science" that their (scientific) authors make reasonable use of nomenclatures/lists of abbreviations. Also, they - most regularly - use units in conjunction to numbers and figures for enabling the reader to quantify e.g. the magnitude of a pre-heating temperature applied. All this finally, for allowing their readers to follow them through their trains of thoughts.

You may consider me a nitpicker, but finally we always seem to end up at a certain point.

That is, exactly where e.g. 'Al' (in this case not abbreviating 'aluminium' but '803056') is impassioned and permanently reasoning to properly use 'common' terminology, simply to battle misunderstandings; and e.g. 'Henry' (note, not representing here the unit of electrical inductance, but 'ssbn727'), who is consistently and patiently requesting 'more details', particularly in conjunction to technical posts readable on this forum.

Like I say - just a friendly note.
Parent - - By 357max (***) Date 06-11-2014 20:00
Quoting from a very old welder "Ah shucks a mighty; you all don't need no dad gum book larnin' to be a welder. Book larnin' is for sissies!"
Parent - - By electrode (***) Date 06-11-2014 21:34
Quoting from a yet elder physicist*:
"There are trivial truths and the great truths. The opposite of a trivial truth is plainly false. The opposite of a great truth is also true...".

I will count "Ah shucks a mighty; you all don't need no dad gum book larnin' to be a welder. Book larnin' is for sissies!" among the great truths.

*) Niels Bohr
Parent - - By Superflux (****) Date 06-13-2014 19:17
Niels Bohr is the one who Busted Albert Einstein for dividing by zero in his "Theory of General Relativity".
Took poor Al a few years to recalculate and develop the Theory of Special relativity.
Parent - By electrode (***) Date 06-13-2014 20:19
Excellent, Superflux!
Now, finally, I can much better understand 'Albert's' paralysed eyebeam, visible in the drawing.
That certainly must have happened shortly before Niels' emotional 'Garfield Cat' outburst. :)
Parent - - By Plasma56 (**) Date 06-26-2014 09:07
Hi Jordan,

It's actually Wednesday and I have a few things to add if your up for it? I have read your post and come to a couple of conclusions based on your posting of material type, thickness and welding process.

Sure, you took a few lumps over your misunderstandings of the process but so what?
You asked, were clarified sharply, and maybe learned something as a result. Perfect.
Lets move on from there and remember to keep learning.

Typically, cracking in aluminum results from contraction forces.  While the properties and grades of Aluminum require conciderations for weldability, filler metal selection, the welding process/rod selection, if the contraction forces exceed the strength of the weld filler metal due to a lack of filler being added to the volume of heat energy causing expansion, you get a crack when thing contract.
Hey. it's 2:49 am, I'm doing my best here.

But that doesn't sound like your customers issues.

Thermal conductivity. You mentioned a thick flange. It takes a whole lot of amperage to over come the heat sink a large aluminum flange can pull away from the weld zone.
While some would argue about the use of preheat on aluminum, there is a time and place for everything and quite frankly, baring any procedural issues, 150-200F will help to preheat the heavy flange while overcoming the issue of thermal conductivity and thermal contraction..
In simple terms, your squeezing everything to get it hot enough to quickly melt the rod in a very small area because the heat is being pulled away. This requires serious amperage on a thick flange. Bet a $5er your using 100% Argon? Try helium.

Preheating, while not reducing actual welding amperage requirements, will if the power sorce is underpowered or lacking duty cycle help over come the initial current draw of thermal conductivity.

Welding aluminum requires the high frequency current, superimposed over the welding current to prevent touch starting and contamination to the electrode. As mentioned, Alternating current has both positive and negative values. The syncrowave being a transformer rectifer machine, typically was a square wave, with the balance control adding more positive or negative values. This machine has a drooping volt amp curve that suggests the difference in width was a variation in arc length or arc wonder with the tungsten while welding but I could be wrong?

You mention the weld appearing cold...Hammering major amps without allowing for a degree of thermal conductivity to pull heat into the material will cause your weld to cool to quickly, the adjacent material pulls and seemingly the weaken area cracks. You describe cracks next to the weld, well this could be due to an elevated arc length or arc wonder liquifiying the metal surface slightly, the weld is thicker, surrounding metal thicker, surface cracking could result from contraction forces from surrounding surfaces?

Pure tungsten electrodes. Well, we have some pretty strong opinions on that one. I'll say this on the matter. All tungsten electrodes have plus and minus benefits. But they are all made of the same mineral, Tungsten. Alloys are added to impart qualities.
Some hold a sharp point better, some hold a balled end better, some resist contamination or self clean some what and some do a bit of all of it reasonably well.
The choice of tungsten wasn't what cause the cracking. What he did with it maybe?

The Dynasty. That's an inverter machine. Allows for wave form, current balancing and frequency variations. Education is the key to understanding and fully appreciating what that machine can do. They do as mentioned hold a preference to an alloyed tungsten electrode but it's my belief that the reason is due to power scorce improvements and efficencies aligned to alloyed tungsten electrode useage.

But talking about welding aluminum, not that I can add much over what most have already mentioned, when the high frequency current establishes the path for the welding current, add more current slowly... this in itself allowing local heat to build, thermal conductivity heat transfer through the material to stabilize and prevent excessive contactual forces, ionic bombardment to clean, and then slowly add more current to establish the weld pool size then away you go. This can be a dutycycle issue depending on the amperage requirements. Helium or Argon helium blending for shielding would reduce this requirement slightly. Remember once the aluminum is hot, it's mostly all hot in that general area, control the heat by reducing current slightly to remain in control of the weld, tail out adding filler to prevent crater cracks. Steady as it goes.

Couple more things. Sometimes a blunt point is better than a sharp point. Slow and steady cause it's not a race. And the cure for me was someone taking the time to do a bit of explaining. Well, you can't say I didn't add to it.
Parent - By MRWeldSoCal (***) Date 06-26-2014 21:54
Thank you for the added insight, I went and watched their welders weld. It seemed to me like a contamination issue as well.  Their welder would pull his filler metal far from the shielding gas, and also was using a very small gas cup. Also he was not leaving the shielding gas on his stops at all just moving right along.

Thanks again!

- - By 803056 (*****) Date 06-07-2014 21:44 Edited 06-07-2014 21:50
Preheat! Why are they preheating aluminum? Are they trying to minimize shocking the molecules, preventing martensite, driving the water out or some other ******** reason?

6061 is a heat treatable alloy. It is heated to a high temperature and then quenched to produce a supersaturated solution of solvent and solute (aluminum and alloying constituents). The quenched alloy system is then artificially aged by holding it at some temperature to trigger precipitation (actually a clumping action within the atomic lattice). The clumping action strains the atomic lattice resulting in distorting the lattice to make the system harder and stronger. Preheat, as well as welding overages the system. Over aging allows the alloying elements that were clumping within the lattice (interstitial) to diffuse (precipitate) to the grain boundaries thereby weakening the alloy system. 

Are they as goofy as that fellow that hangs around with Mickey Mouse and Pluto? You do not preheat aluminum.

What they are experiencing is sometimes referred to as "arc erosion." The phenomenon has been described in one of the links Henry provided.

Other than that, it sounds like they are doing a bang up job. Throw the preheat torch away, flush the surfaces with isopropyl alcohol, brush the joint just before welding with a stiff stainless steel brush (cleaned with isopropyl alcohol), and turn up the damn amperage. Wire brush the weld and adjacent surfaces after the welding is completed.

I feel like we are repeating the same issues with you time after time Jordan.

Parent - By electrode (***) Date 06-07-2014 23:05
Quote: "I feel like we are repeating the same issues with you time after time Jordan.".

Obviously I have not overlooked something here.

Parent - - By ssbn727 (*****) Date 06-08-2014 20:42

I almost fell off my chair from laughing so hard when you wrote:

"Preheat! Why are they preheating aluminum? Are they trying to minimize shocking the molecules, preventing martensite, driving the water out or some other ******** reason?
Are they as goofy as that fellow that hangs around with Mickey Mouse and Pluto? You do not preheat aluminum." Too funny!:grin::lol::yell::lol::yell::lol::yell::cool::cool::cool:

Jordan, Al and Electrode are totally correct! It's aluminum, not steel... Read any decent book on welding metallurgy that covers Aluminum and you will find the same explanation that Al has given you so eloquently... And yet on a very simplified manner so you could digest it but, it seems to me that you're not that hungry... :eek::surprised::roll::smile:

As Al mentioned, you don't want to overage a heat treatable Aluminum alloy like 6061 T6... Good Read Electrode.:lol::cool:

Parent - - By 803056 (*****) Date 06-08-2014 22:59
Hey, I figure a little humor makes the day go by easier.

Parent - By Milton Gravitt (***) Date 06-09-2014 10:07
I was waiting on Al. I know he couldn't let that go.

Parent - - By electrode (***) Date 06-09-2014 09:14
Thank you, Sir.
Parent - - By Lawrence (*****) Date 06-09-2014 11:45 Edited 06-09-2014 11:57
Others have had most of the fun.

I did not notice anybody taking the original poster out to the woodshed for suggesting the use of a pure (green) tungsten !

A penny spent on pure tungsten electrodes is a penny wasted.

This fact has been established for the last 30 years.

If your fancy technical or textbook even mentions pure tungsten electrodes in a way other than an admonition to avoid them.... This book belongs in the trash.

Any alternative is better than a pure tungsten electrode... This includes thorium.

All inverters (Dynasty style) GTAW power supplies state up front in their owners manuals, specific instructions to avoide pure tungsten electrodes.

May we please step into the 1980's

Original Poster:
Please read this series of articles by Mike Sammons of Miller Electric.
He will set you straight on the functions of electricity in both cleaning action and High Frequency.

Parent - - By electrode (***) Date 06-09-2014 12:36
Good point(s).
Well adding to what's also been stated by Allan:
"Hello Jordan, if he is using a Dynasty: don't use the pure tungsten. Check the literature and manual for that machine and it specifically refers to NOT using pure tungsten.".
Parent - - By ssbn727 (*****) Date 06-10-2014 02:02
The OP stated that they were using a synchrowave Lawrence... Green is a waste on a dynasty or similar inverter power source... Now green W isn't the best choice with a synchro either as the ideal pick would be yellow which is zirconiated... You get more bang for the color with yellow with pr-inverter power sources for aluminum GTAW.

Parent - - By Lawrence (*****) Date 06-10-2014 11:48
I love you Henry.

I'll stand my ground on this one..

Pure tungsten is not a valid choice for GTAW period.  For any reason, with any type of power supply... On any day of the week, Rain, Shine, Fog or chocolate covered doughnuts.

If all I ever did was weld Aluminum... And I mean exclusively... I would select Zirconium...  In my opinion the arc stays on the tip of the sharpened electrode better with this type of tungsten than all others.

In a practical world I usually select Lanthanum 1.5 %    It has a higher current carrying capacity than either pure or zirconiated electrodes and will weld steel on DCEN or Aluminum on AC equally well.

I will say on a final note that the electrical functions/emissions or the way the arc stays on the electrode tip has in my experience varied from brand to brand of electrode, even when the percentage of doping remains the same....  Probably a difference in Sintering/Powder Metallurgy processing
Parent - By electrode (***) Date 06-10-2014 12:12
Again - valuable points.
I'm wondering though whether this with these "chocolate covered doughnuts" is really assured.
On the other hand, coming from you, it certainly is.
Sorry, I simply couldn't resist. :)
Parent - - By ssbn727 (*****) Date 06-11-2014 06:36
Don't get me wrong Lawrence,

I'm not disagreeing with you as far as pure W's usefulness for GTAW is concerned... All I'm saying is that if left with only a choice between green and red, then green is the preference IMHO... Didn't I mention that Zirconiated gives you the best bang for the color in my previous post? There was a time not too long ago yet, before inverters that the only choices (The Dark Ages:eek:) one had to use with GTAW were Green, Red and maybe Brown in stock @ most LWSS's, and if one wanted Yellow (Zirconiated) then one would have to place an order because the store most likely didn't have it in stock... it's not that it wasn't available to purchase... It's just that not as many customers requested zirconiated W.

1.5% Lanthanum is the optimal all around choice for inverter type power sources for sure but, prior to the age of inverter type welding power sources one would be very hard pressed to be able to purchase that flavor of W...:grin::lol:

As far as the sintering and powder metallurgy processing is concerned  I agree and it's primarily due to some manufacturers keeping up with the latest methods of both sintering and powder metallurgy while other manufacturers still use methods and equipment that are now considered obsolete... There are other reasons but primarily it's because staying current with the latest improvements in the technology to produce @ such high quality on a consistent basis. No disagreement here Lawrence.:surprised::grin::lol::twisted::wink::cool:

Parent - - By MRWeldSoCal (***) Date 06-11-2014 17:58

Ok so I have for sure asked the same question twice, heck maybe 3 times.  I have done much more reading and I think I have a more fine-tuned question.  What is it specifically about the electric characteristics of DC+ that causes it to clean?  Is it simply that the current is traveling to the electrode and therefore removing "flakes" on its way up, and therefore penetration of DC- is when its going opposite?  I am not an engineer; I am however on my way to being one if I can manage it with a full time job.  Also with the tungsten, on a molecular level why is one transferring current better than the other and what actually is changing chemically to create these differences? 

Parent - - By Lawrence (*****) Date 06-11-2014 18:33
Here are some excerpts from posts of the past:;hl=Always%20exchange;hl=Always%20exchange

After reading the posts....(and pictures)  bring your questions !

Cathodic Cleaning?

Cathodic Bombardment?

There are two schools of thought about how "cleaning action" really occurs during DCEP and the DCEP half of an AC GTAW welding cycle...  Before I discuss the two differences, let me make it clear that it really doesn't matter which school of thought is correct. 

Science knows it happens.. but scientists cannot see electrons or Ions.. Not even with an electron microscope..  Electrons are a thing that can travel about 186,000 miles per second through solid copper and are very small, so you just can't see them.

Discussion will be based on an alternating current sine wave applied to a GTAW weld arc on aluminum:

Theory #1   Is that During the DCEP side of an AC half cycle electrons flow from the work to the electrode and Ions flow from the electrode to the work <always an exchange> ...  When the Ions that are comming down strike the aluminum oxide coating on the surface of the base metal it blasts the oxide away.. This is important because the oxide has over twice the melting temp as the aluminum base metal and the oxide is also almost as hard a diamonds. So it needs to be removed.

Theory #2   During the DCEP side of an AC half cycle electrons flow from the work to the electrode and Ions flow from the electrode to the work <always an exchange> ... When the electrons leave the work and begin their travel toward the electrode they actually, in that process lift the aluminum oxides from the base metal. 

Things we can know...  Cleaning Action occurs during DCEP and the DCEP side of an AC cycle.

So it really doesn't matter one little bit whether they are blasted off by Ions or lifted off by electrons.. My illustration will be of Theory #2  even though I was originally taught Theory #1 and still think it is the best theory, even though I can't defend it with real evidence.

I see no real reason to debate, since the welding arc is controlled the exact same way regardless if Theory #1 is true or Theory #2 is true
Parent - By electrode (***) Date 06-11-2014 18:50
Dear passengers, welcome aboard!
Lean back and enjoy the flight.
Parent - - By 357max (***) Date 06-11-2014 19:54
Again Alternating Current is the alternating between the maximum positive value and the maximum negative value passing through the zero line 60 times per second/60 hertz. It is not direct current until it is rectified which blocks the flow of current in one direction. This would make it direct current electrode positive or direct current electrode negative.
An interesting phenomenon occurs when welding aluminum, the oxide layer may rectify the alternating current creating direct current component. This energy goes into the transformer as heat.
Parent - - By Lawrence (*****) Date 06-11-2014 20:05
AC Rectification

A nice article by my friend Dennis Klingman
Parent - By 357max (***) Date 06-11-2014 20:37
"On 60 Hz AC, cleaning is obtained on each positive polarity half cycle..." and "...during the negative polarity half cycle" This article is from page 5 figure 8 of the GTAW Guidebook of the James Lincoln Foundation. This is from the AWS Welding Handbook 7th Edition Volume 2. The Ninth Edition Volume 1 page 29 Figure 1.27 has the Electrode Positive and Electrode Negative Wave Form turned around (the negative is shown above the zero line and the positive is shown below the zero line).
Parent - By kcd616 (***) Date 06-12-2014 02:33 Edited 06-12-2014 03:00
my friend, going to bring up what I do now for aluminum and what I was taught and new tech, I would love to try
I use a/c and argon with 2% thor tungsten...on my ranger 250 gtx
my reason is everything is a multi tasker, I can use everything for all gtaw, and the gas for gmaw
try to cut costs for my customers, and myself
now on to what I think should be done
a/c and helium with pure W
and the one I really want to try with it is, the pyramid on the dcen and the square on the dcep
maybe more cleaning and better penetration
Parent - - By 357max (***) Date 06-11-2014 22:12
Did AWS A5.12 change the color code? EWZr-1 ~ Zirconiated is brown and EWTh-1 = Thorium (1%) is yellow. EWCe-2 = 2 % Ceriated was changed from Orange to Gray.
Parent - - By ssbn727 (*****) Date 06-12-2014 15:44
Whoops! I meant Brown and yet I typed yellow... Oh well... I hope this doesn't cause the rapture to occur sooner than expected.:eek::twisted::roll::grin::lol::yell::lol::yell::grin:
Usually I double check before I post and this is one of those rare occasions where I didn't and the result is - well you know what I mean... It's not the first time I have been incorrect and it certainly won't be the last time.:twisted::yell::lol::yell::lol::yell::lol::wink: Thanks for the correction 357 Max...:surprised::grin::wink::cool:

Jordan, I believe Lawrence put up a very good reply along with an appropriate illustration for your query regarding your first two questions: "What is it specifically about the electric characteristics of DC+ that causes it to clean?  Is it simply that the current is traveling to the electrode and therefore removing "flakes" on its way up, and therefore penetration of DC- is when its going opposite?"

As far as your last question is concerned, I haven't had the time to give you a decent answer so, I'm going to defer to anyone else who wants to... Normally I would but, this week has been extraordinarily busy for me so I apologize for not responding with an explanation.

Parent - By 357max (***) Date 06-13-2014 13:40
Someone with some book larnin' has determined that electricity (electrons) travel from the negative pole to the positive pole. Then the mysteries of mysteries; the gas ions (plasma) travel positive to negative. It is the gas ions that break up the oxide layer. Figure 3.15 p 120 AWS Welding Handbook 9th ed volume 2 ??? As some would say ~ go figure
Parent - By kcd616 (***) Date 06-27-2014 05:56
I liked the 1970's:wink::evil::lol:
Parent - By MRWeldSoCal (***) Date 06-10-2014 15:07
The humilation has given me a ruble in my stomach.  Looks like I try and eat some books.

Thanks guys!

Parent - - By MRWeldSoCal (***) Date 06-10-2014 14:59
These are who walk through the door and ask for help.  It can be hard to describe every deail of what I a trying to explain.  It schocked me too. Seemed simple. Ill be sure to think before I ask next time.

Parent - - By Lawrence (*****) Date 06-10-2014 15:09
I thought it turned out to be a pretty good conversation :)

Worry less friend..
Parent - By electrode (***) Date 06-10-2014 15:11
"I thought it turned out to be a pretty good conversation :)."

So did I.
Parent - By 803056 (*****) Date 06-11-2014 00:15
Jordan, it wouldn't be any fun if we didn't play with you a little bit. You are part of the community. We're just poking the lion to hear him roar a little.

Al :eek:
Parent - By Metarinka (****) Date 06-12-2014 23:59
As a note Al, I recall preheating some aluminum parts for tolerancing issues during fitup, In fact I recall some procedures specifying the fitting and tacking had to be done at 100-200 deg f due to dimensional tolerances.    This was long enough ago that I can't recall the specifics though, I've managed to stay away from designing aluminum welds my whole career now.
- By goldybowen21 (**) Date 06-24-2014 18:49
I love when you guys answer questions...its always lively and full of constructive feed back
Up Topic Welding Industry / Technical Discussions / High Frequency Cracking 6061

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