Weld weave size Vs. mechanical properties

Date 10-31-2008 19:01

In my experience its 2.5 electrode diameter rather than 1.5, 1.5 can hardly be called a weave but a "shake of the hand"
If your material/weld dont have specified impact properties, why would it matter?

If you qualify a procedure with a 5 times diameter electrode weave, well.....you can weld with a 5 times diameter electrode weave as you has just proved it's mechanical properties are acceptable according to the procedure you qualified it to.

If both hardness and impact is required you might want to be a bit more carefull with your heat input, and you might only be permitted - according to some codes - to raise or lower your heat input by 25%

3.2

By RonG

Date 10-31-2008 19:32

In some material the Interpass temp affects the yield strength. With that in mind you can probably figure how to limit your self.

The rule of 1.5 or 2.5 is kind of moot when you run a SAW bead 1/2"-5/8" wide with 1/16" wire. But you are traveling greater than 12" per minute so you do not greatly effect preheat in front of you or impede the quenching behind.

By kipman

Date 10-31-2008 19:22

3.2 is right. It relates to heat input, and it depends on the code you are working to. I believe he refers to EN 15614 when he indicates a code that limits heat input to plus or minus 25%. I am a bit more familiar with AWS D1.1, which limits heat input in a different way (it gives max ranges on amps, volts, and travel speed from that qualified for a qualified procedure). The parameter of interest for your question is travel speed (i.e. width of weave).
Max weave is really dependent upon what you can get to pass when you run your test plate. If impact testing is required it likely will not be a significant weave.
Mankenberg

By Metarinka (****)

Date 10-31-2008 20:39

on the metallurgical side, as mentioned a large weave or large buildup in single bead can influence various factors such as;
penetration, dilution, cooling rate, residual stress and distortion. In general for welding, higher heat input is usually considered bad and a weave bead will generally lead to higher heat input in a concentrated area. This could cause things like martensite formation, intergranual corriosion of stainless steels, as well as an excessive HAZ or heating of base material. However it is really on a case by case basis as to whether or not it will impact strength, and wether a larger bead will increase heat input into dangerous ranges.

I just heard from a classmate the other day that the manufacturer he works at bans weave beads.

From a practical standpoint especially in certain joints and positions wider weave beads would not be possible or practical.
ON a curious note back in my days of TIG pipe welding I could successfully do a single weave bead cap on some pipe, it would be approx 2-3 times the cup diameter making it a 1-2" wide cap pass. At that point it no longer is a weave as much as stringer bead that zigzags up the pipe. It worked out beautiful though and was very fast.

By 3.2 Inspector (***)

Date 10-31-2008 21:01

It looks to me like you reversed some things :)
A high heat input will lower the 8/5 cooling rate and consequently not promote martensitic transformation.

In some cases a wide bead is prefered in order to minimize the stress concentration created by an unequal bead surface, as it is the case with operating temperatures in the creep regime.
Even in some cases the bead is grinded flat - equal to the pipe.

3.2

By hogan

Date 10-31-2008 21:27

In addition to what others have mentioned, AWS D1.1 lists some parameters for prequalified wps' like max root pass thickness, max fill pass thickness, max single pass fillet size, and max single pass layer width (table 3.7-08). For prequalified WPS' these are to be followed in addition to figure 3.1 width to depth limitations.

By 3.2 Inspector (***)

Date 10-31-2008 21:34

I am not familiar with AWS d1.1 at all :(
But as I see it, the width to depth ratio is to avoid sulidification cracking and is rarely an issue when you have a wide bead.

I might be wrong....

3.2

By Metarinka (****)

Date 10-31-2008 23:04

you are right a larger bead will generally slow the cooling rate through the critical zone which would reduce the likelyhood of martensite formation. However lengthened periods of time above critical temperatures (or by putting more heat into the Base metal) that you would expect with a weave bead can lead to things like grain growth and promote the migration of carbon and other alloy elements which could lead to Carbide precipitation. Not to mention other nasties.

width to depth ratios are generally there for deep penetration processes such as SAW due to solidification cracking. This function has to do with grain seeding and growth as the metal passes out of the liquid phase but probably isn't applicable to the topic at hand

By 3.2 Inspector (***)

Date 11-01-2008 15:00

I dont have a clue about SAW :)
Its to mechanized to be interesting LOL

3.2

By ROBERT HANSON Date 11-01-2008 17:37

Howdy to all-
There have been some very valid points made-input temps,diameter multiples,etc. Alas,it has been my experience that the weave width is determined by the thickness of the material being welded.
Good Luck-Robert

By Stephan (***)

Date 11-02-2008 14:22 Edited 11-02-2008 14:37

Charles,

please allow me to ask a question, just to get the conversation going.

Your inquiry is truly most interesting thus, it were valuable to know your own opinion about the topic.

As you are the initiator of this thread I am sure that you have already considered the pro's and con's for either using the weaving bead technique or even avoiding it.

For instance it were interesting for me to know where the /quote/ "(...) common rule..." /unquote/ is coming from. This, since I have honestly never been confronted with this rule, by now. What should, in your opinion, be the benefit of such a common rule which may, in some cases (e.g. small diameters), be easily debilitated, as proven by 3.2.

To my way of thinking your question is too intricate - and too important - to be answered by a general statement, but must be treated very specifically to the welding application you would like to perform. This again needs more detailed information in terms of all the subitems already mentioned by the appreciated forum fellow members who have posted their replies by now.

Of course, finally welding is "just joining two sheets of metal one to another", but all of us do certainly know that this is only true for the very first view. The way to this joint however, is to be recognized being much more tricky when having a look to below the surface.

Just even so that even "hardness" may be treated as a particular "mechanical property" of the parent material. It's all about perspective, to speak with John Wright.

In other words.

A bit more defining of what yourself does understand e.g. when saying /quote/ "(...) what is the maximum weave that you would probably be safe with for wire processes..." /unquote/ I mean, would lead to the possibility to create a more concrete response. Wire processes may show a wide variation e.g. from GMAW --> FCAW --> SAW to name only some of the most important ones. I hope you may understand what I mean. It's just a humble try to avoid "stumbling about in the dark" and to provide you more accurate information.

By the way, I would recommend to do a "Weave" or "Heat Input" search within the forum. I am sure you may find loads of loads of precious information to your topic.

Best regards,
Stephan

By DaveBoyer (*****)

Date 11-03-2008 02:56

Stephan, I too have read the "1.5 X electrode diameter" rule, but I don't remember just where.
With .035" - .9mm or other rather small wire it does seem that it would be hard NOT to excede the 1.5 rule with a manual procedure.

By aevald

Date 11-03-2008 03:15

Hello Dave, I believe that ASME or Possibly API might have such a "rule", yet, I also believe it refers to the SMAW process and doesn't include the others. But don't take my word for it. I have even heard 3X, yet, here again I couldn't site a specific code or section of a code. In many past threads this has been discussed at length and I'm sure it will continue to be discussed. There is also some language, possibly D1.1, where bead width is limited to not allowing slag to solidify before it is welded over. I have read of this being applied to removal of slag from previous beads before applying any additional filler passes and also in reference to weaving during the application of the same weld pass. Will be watching for more to come. Best regards, Allan

By DaveBoyer (*****)

Date 11-03-2008 03:46

Allan, the only code I know is FC2002 :-) The 1.5 X was mentioned specificly for some particular circumstance someplace, but I cant remenber where. Other books I have suggest various weaves for general work.

By aevald

Date 11-03-2008 04:40

Hello again Dave, I believe FC2002 holds a myriad of very interesting and applicable circumstances to cover this. Many still try to apply this code everyday(anyone new to this "code" please know that it is a fictional code!).
On the more serious side, I believe all of the codes have evolved immensely with the advent of the many different alloys and material improvements of recent years. Once upon a time there were a fairly limited amount of different materials that were used in most piping, structural, and industrial applications. Now there are a vast quantity of very application specific materials and alloys that require some very specific and controlled joining processes and parameters. Weaving the welding beads can have both detrimental and applicable uses depending upon the materials and their applications. That is why, I believe, in some instances it is acceptable, while in others it is a definite no no. The more important thing to realize is the need to know the difference of when. Best regards, Allan

By pipewelder_1999 (****)

Date 11-03-2008 14:10

Here is a previous discussion on the subject that refers to the "slag freezing" . http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=78588;hl=slag%20freeze.

Some interesting information with varying opinions.

By Stephan (***)

Date 11-03-2008 07:07

Hello Dave,

first off, thanks a lot for your once again very appropriate response.

Yes, you are certainly right. And even though I have never been confronted with this rule in my personal experience, I have nonetheless read something about it before.

If memory serves right, it was in a close relation to the SMAW welding of High Strength Low Alloy Steels and here again in regard to the use of SMAW in positional welding (fillet welds).

As far as I remember correctly the length of bead deposited had to be limited to a particular value to meet the t8/5 cooling conditions and hereby to meet the mechanical post weld properties of the material. Due to this limitation it appears necessary and of course reasonable to limit the weaving amplitude to limit again the "heat input". I ain't remember if it were 1.5 times the electrode diameter, but however, it could be that it should be 1.5 x the diameter.

Even this was the reason for me to ask "Uncle Chuckles" for more or more detailed information, since it might be that he has meant this "rule" but... it might be also that he did not.

Or to say it with Allan and his great responses and his most excellent statement /quote/:

"(...) Once upon a time there were a fairly limited amount of different materials that were used in most piping, structural, and industrial applications. Now there are a vast quantity of very application specific materials and alloys that require some very specific and controlled joining processes and parameters. Weaving the welding beads can have both detrimental and applicable uses depending upon the materials and their applications. That is why, I believe, in some instances it is acceptable, while in others it is a definite no no. The more important thing to realize is the need to know the difference of when. (...)" /unquote/

This expresses much more exactly what I meant when I wrote /quote/ : "(...) your question is too intricate - and too important - to be answered by a general statement, but must be treated very specifically to the welding application you would like to perform. (...)" /unquote/.

As I said, it were excellent to receive somewhat more precise background information of the initiator of this interesting thread. Even since the high number of materials (both parent- and filler), consumables (shielding gases, fluxes,...), processes, ..., allows an almost infinite number of variations making it at least in my humble opinion nearly impossible to answer the question in a general way. And furthermore, I assume honestly that every thread initiator has had his/her own ideas and thoughts on a particular issue before he/she is going to start a thread in the forum. And even thsese thoughts - as far as they were existing - were interesting to get to know. ;-)

Thanks and best regards,
Stephan

By pipewelder_1999 (****)

Date 11-03-2008 13:40

There have been some very fine responses and for some reason my mind is having a hard time grasping them all. If I repeat something that is already covered, forgive me.

Here are some things I think I know.

The limits placed on weave width have been generated to control heat input. The wider you weave, the slower you travel, the hotter it gets etc..

A better variable to control is heat input based upon amps, volts, and trave speed.

Some materials are more sensitive to excess heat input than others.

Excess heat input affects impact strength. Tensile strength is not affected to a degree that it is outside the limit of the code.

Not all production welds are concerned with the impact properties of the weld.

ASME does not address bead width as a ratio to diameter in any document I am aware of. I have only seen 2.5 used in the SA/SFA specs for filler materials.

AWS D1.1 does not control the width of a weave bead for prequalified procedures for SMAW at all. For vertical FCAW the limit is 1" bead width.

For procedures qualified by testing in D1.1 in which impact testing is performed there is no limit on the width. It is only addressed as a change from "stringer to weave".

A weave bead that is 3/4" wide can have an extremely large variataion in heat input depending upon the thickness of the pass. I have welded weave beads that were caps that had faster forward progression than much narrower beads with little or no weave.

I have been welding for 25 years. Very seldom have I welded without manipulating my electrode. There is no clear definition at what amount of "transverse oscillation" is allowed before it becomes a weave. I don't have the skill or know the proper settings to run a vertical fillet weld with GMAW without some "transverse oscillation". A 3/16" fillet weld requires me to weave.

My answer/discussion to your question is . Yes, a weave bead does affect mechanical properties. Sometimes it just doesn't matter. Controlling the "maximum weave" does not control heat input as well as controlling actual heat input by monitoring amperage, voltage and travel speed.

One additional variable is the base material thickness. Thicker material could take more heat input without affecting the properties.

A stringer bead with a 5/32" 7018 at 185 amps may put a different amount of heat into a piece of 1/4" plate than 2 beads of the same volume with a slight weave using 3/32" electrodes.

I think the topic of weave beads versus stringer beads has many different viewponts. Some are based on education, experiences, "welding wives tales", etc. Mine may be a combination of those. At least it goves you even more to chew on.

By rodofgod (**)

Date 11-03-2008 23:03

Hi All!

I agree with pipewelder!

Most 'limits on weave width' are stipulated in the welding procedure, these are written by the Welding Engineer!

As pipewelder says,

"A weave bead that is 3/4" wide can have an extremely large variation in heat input depending upon the thickness of the pass. I have welded weave beads that were caps that had faster forward progression than much narrower beads with little or no weave."

Thickness of weld deposit has much more effect on weld metal mechanicals than weave width alone! Many "Welding Engineers" often mistake this fact, thus over the years weave width has become the bone of contention.

Regards

By Uncle Chuckles (*)

Date 11-06-2008 21:34

Thankyou all for your great responces

My question came from the production of company specifications. Currently the engineering firm that i work for is constructing a pressure acid leaching autoclave. Our standard spec's for welding of carbon steels has nothing concerning weave width. I know from experence (as very limited as it is, I am 24 and 2 years out of school in Canada) that weave width has an effect on impact properties depending on the location of the wide weave in the joint. If the next pass ontop of the wide weave does not temper the one below it, impact specimens suck, and hardness are through the roof for that particular location in the heat affected zone. I was just wondering what the many industry professionals and great minds that frequent this forum thought. The general "Rule" of 2.5 electrode diameter came from my again limited experence working with the production of welding proceedures. I have tryed to find a similar requirement in the codes I have access to and have found nothing. as far as what wire processes i was refering to, it was just a general question, I know that wire size is a tiny bit larger on SAW then it is on GTAW lol. Sorry for taking so long to respond for they had me in Malaysia doing inspector type stuff.

Thanks again to all who responded

Charles