PQR results

Date 08-27-2009 15:00

I believe the 100% CO2 would develop a Hotter situation which in turn would increase the hardness, the problem would be if this hardness took away from the percent of elongation required to Qualify.
Hope this Helps more than Hurts

By jwright650 (*****)

Date 08-27-2009 15:02 Edited 08-27-2009 15:05

yes, gas makes a difference

I believe most electrode mfgs include as welded mechanical numbers using different mixes of gas, so you may find similar documentation include on their data sheets. A quick scan over some other data sheets show that the 100%CO2 vs 75/25 favor higher numbers for the 75/25.

By CHGuilford (****)

Date 08-27-2009 16:13

I know that CO2 contributes carbon to the weld metal, or so I have read anyway. So more CO2 means more carbon in the mix.

By js55

Date 08-27-2009 16:53

I have to disagree guys. Though gas will certainly influence mechanicals, I cannot imagine it influencing the mechanicals as much as 28ksi. And 18 ksi below the filler metal specified min. There is something else going on here besides gas.
Even with the carburizing/oxidizing nature of CO2 I cannot believe that it would reduce the strength of the filler by 18ksi. This is over a 20% strength reduction. The carburizing would tend to make it stronger in general, and I doubt seriously the oxidizing would reduce low alloy content so much so as to cause this much strength reduction. I have never seen 100% CO2 reduce tensile strength like this in any alloy I have ever worked with.

By jwright650 (*****)

Date 08-27-2009 17:04

I didn't crunch his numbers nor notice the amount(%) of reduction in strength....so you may be right about some other factor being at work here.
I briefly glanced through a few wire mfg's data sheets and saw the trend.

edit: with the different mix wouldn't the parameters change some?

By Stephan (***)

Date 08-27-2009 17:16 Edited 08-27-2009 17:19

And I would like to agree, Jeff.

Even though I am not familiar with the designations of both filler and parent material and even though different shielding gas compositions proved to have influence on the mechanical properties, I am not sure that this deviation would be explainable only by the different shielding gases alone.

Huuuh... what a sentence. I should remember an appreciated Professor who told me that long sentences appear to be regular in German speaking countries.

But seriously. As memory serves correct. I would have tended to state the opposite.

100% CO2 = 'lower' mechanical properties --> due to an increased reduction of alloying elements (Mn, Si) --> bead reactions
90Ar/10CO2 = 'higher' mechanical properties --> due to the contrary = less bead reactions

As I remember correctly as well, GMAW under pure CO2 may significantly reduce the impact toughness with High Strength Steels, in particular with lower temperatures.

Anyway, as we have already discussed the immense importance of testing conditions (you remember the CV-Tests accomplished in the UK), it would be very interesting to get knowledge of how even these conditions exactly were as the tests were conducted.

Just my .02$ for what it's worth.

EDIT: Extremely interesting thread. I wish Jon and/or Al would step into this!

By Lawrence (*****)

Date 08-27-2009 17:37 Edited 08-27-2009 17:42

Kinda hard to make any kind of solid statement since the poster did not even tell us what process these shield gasses applied to.

Assuming Gas Shielded FCAW the difference in mechanicals is pretty significant 100% CO2 vs 75/25 but no place near 20%

Here is a link to a typical E71T-1 data sheet that provides typical mechanical results with both gasses... Looks off the top of my head that the difference is someplace between 5 and 10 percent, with the mixed gas producing higher numbers in both tensile and yeild.

Difference in carbon in the deposit between the two gasses was recorded at 0.001

http://www.hobartbrothers.com/pdf/datasheets/Excel_Arc71.pdf

I don't know of any gas shielded FCAW electrodes that have manufacturer approval of a 90/10 mix

Possibly the strangely low readings come because the electrode is not designed to perform with 90/10 ????

If we are talking about short circuit GMAW... Forget everything I've said.

By jwright650 (*****)

Date 08-27-2009 17:45

the CVN numbers take a small hit also Lawrence if switching from 75/25 to CO2.

By Stephan (***)

Date 08-27-2009 17:55 Edited 08-27-2009 17:59

Lawrence,

I should have edited my previous post by better writing: "I wish Jon a/o Al a/o Lawrence would setp into this!" :-)

Most excellent...

Anyway, may I kindly ask what '...90thou wire..." means?

EDIT: I forgot before. As to the best of my knowledge, it's mainly the O2-content of the deposited weld metal what might have a considerable influence using solid wire GMAW with un- a/o low alloyed steels. But like I say. It been a while since I have occupied myself with those topics.

By motgar

Date 08-27-2009 18:30

Stephan,

I think what 52757 meant was 90,000 psi tensile welding consumable, in this case a wire consumable.

or roughly,

620 MPa tensile strength

By Stephan (***)

Date 08-27-2009 18:36

Ahhh!

I see! Yes, this makes sense!

Thanks motgar!

By 52757

Date 08-27-2009 18:46

Sorry for the inadequate information. Base material is A514, filler metal is E91T1-K2M (FCAW) pre heat of 125 with a max of 400 between passes.The 90/10 test was .062wire --310amps -25vlots. co2 test was .062 wire--220 amps--- 26volts--- I know that that is a considerable difference on amps but that is what the old PQR sheet has on it. Exteremely busy at the moment but I will look up gas info. Earlier manufacturer listed approved gas mix of 90/10 if I remember right. I will double check this later. Thank you.

By ssbn727 (*****)

Date 08-27-2009 20:09 Edited 08-28-2009 05:07

Well now, do you see what type of CONFUSION YOU JUST STARTED???

Unbelievable!!! You really MUST NOT FORGET TO INCLUDE THESE DETAILS WHEN YOU POST HERE FROM NOW ON WHEN POSTING SUCH A QUERY!!!

NOW I know for sure I'm not losing my mind!!! :) :) :)

You say you don't have the time??? Next time - PLEASE MAKE IT SO 52757!!! I cannot stress enough the importance of being very specific as well as including as many details as necessary before posting such a query in the future, and if one doesn't have all of the necessary pertinent information, then please do not post the query until one does have all of it on hand!!! ;)
Thank you for understanding what I am emphasizing here. :) :) :)

Respectfully,
Henry

By ssbn727 (*****)

Date 08-27-2009 20:31 Edited 08-28-2009 10:31

Hi 52757!

One more thing because, I think this is also an important parameter which you failed to include in you next post which gives us a whole bunch more of info in order to help you better. So here's the million dollar question or two: In the two tests, was the travel speed the same as well as the wire stick out length??? Was the Arc Plasma cone substantially wider when using 100% CO2 as opposed to when using the 90% Argon (Quote: "If I remember right?") with a balance of only TEN% CO2??? Finally, what was the base metal thickness if you say that your pre-heat temp was only 125 degrees and when you say 125 do you mean 125F or 125C

Btw, it's the acicular ferrite that needs to form in order to achieve such high ultimate unit stress of 100,000 and the necessary strength/ductility as well as resistance to crack propagation in order to achieve such high yields and if I may, I'd like to use an explanation via wikipedia... Acicular ferrite consists of a fine structure of interlocking ferrite plates (sometimes called 'dark etching').

Acicular ferrite is formed in the interior of the original austenitic grains by direct nucleation from the inclusions, resulting in randomly oriented short ferrite needles with a 'basket weave' appearance. This interlocking nature, together with its fine grain size (0.5 to 5 um with aspect ratio from 3:1 to 10:1), provides maximum resistance to crack propagation by cleavage.

Acicular ferrite is also characterised by high angle boundaries between the ferrite grains.This further reduces the chance of cleavage, because these boundaries impede crack propagation. It is reported that nucleation of various ferrite morphologies is aided by nonmetallic inclusion; in particular: "oxygen-rich" inclusions of a certain type and size are associated with the intragranular formation of acicular ferrite. Meaning that the Oxygen in the CO2 can help in forming acicular ferrite in Q&T steels such as an A-514 grade!!! ;) If this does not occur with a Q&T steel like A514 then you'll have too much martensite & bainite instead - making the weld and HAZ relatively brittle in comparison and therefore resulting in a 20% loss or more in strength in some cases!!!

Acicular ferrite is a fine Widmanstätten constituent - named after "Count Alois von Beckh Widmanstätten" and, also known as Thomson structures which are very similar to the long nickel/iron crystals, found in the octahedrite iron meteorites and some pallasites. Acicular Ferrite, which is nucleated by an optimum intragranular dispersion of oxide/sulfide/silicate particles.They consist of a fine interleaving of kamacite and taenite bands or ribbons called lamellæ.
( http://en.wikipedia.org/wiki/Widmanst%C3%A4tten_pattern )

Commonly, in gaps between the lamellæ, a fine-grained mixture of kamacite and taenite called plessite can be found. Composition control of the weld metal is necessary in order to maximise the volume fraction of acicular ferrite, because excessive alloying elements can cause the formation of bainite and martensite. Just as I mentioned it above in previous paragraph! ;)

Finally, one does not approach welding Q&T steels in the same manner as one would approach welding mild or low carbon steels because after all, they are distinct and different animals - so to speak!!! :) :) :) I never once said that CO2 was the BEST possible gas for welding Q&T steel... I was trying to say that because the 90-10 CO2 balance mix had only 10% CO2, it would not be enough to cause sufficient penetration irrespective of the arc characteristics which is NOT what I was trying to emphasize here...

Ed Craig even states that you need at least 20% Co2 in order to start at achieving desirable arc characteristics and it probably was total fluke in using the 100% CO2 which may have contributed slightly in the overall results of much higher mechanicals (more than likely it was the flux chemicals in the filler metal itself) - who knows??? Well - ummm, now we know that this simply wasn't the case since 52757 made his second post!!! So the next time I notice someone misinterpreting some critical information, I'm just gonna sit back and watch the show from now on!!! I try to be helpful and everyone wants to react by saying "How can you - this, and how can you - that..." Suit yourselves from now on!!!

Here's a bone for all you salivating hungry dogs!!! ;) :

http://www.iiw-iis.org/iiw/extranet/static/WW-2004/1-2/Hydrogen.pdf

Enjoy the read. :)

Respectfully,
Henry

By ssbn727 (*****)

Date 08-27-2009 18:23

Hi Jeff!

Pardon me for being so blunt but, unless I need to get a new prescription for glasses, The higher readings in "ultimate unit stress" according to the originating poster was with the 100% CO2 and not the 90% Argon - 10% balance of CO2, and if you don't believe me, then read the original post which I copied and pasted below...Quote:

"Hey guys, question on PQR results. 2 test were ran, on 1 the ultimate unit stress, psi were in the 72900 range, on the other the results were in the 100000 range. A514 materisl with 90thou wire. The only difference on these two test were the gas. The lower readings were using a 90% argon 10% co2 the higher reading was using 100% co2. Would the gas make that much difference on the results?"

So now that gas differences have been clarified in depth, one can most definitely agree that there is a substantial difference in arc energy being transferred when CO2 is used as the shielding gas when compared to 90% argon, and a balance of only 10% CO2 which would result in a much lower arc energy transfer therefore, easily contributing to an over 20% strength reduction when compared to 100% CO2!!! ;)

So Jeff my friend, forgive me if I may sound like I'm poking fun at you, but I think I can assure you with some degree of confidence that you will not see what you thought you saw with respect to 100% CO2 reducing the tensile strength in the way you initially interpreted to occur... Btw, I need to go see the Eye doctor soon since after all - it has been roughly a year since I went to get my eyes checked for any potential damage that may, or may not have occurred... And as I am a diabetic, I need to be vigilant with respect to the potential formation of cataracts which can form if left unchecked so, I'm kind of glad I read this post as it has shown to me that my eyes are still capable of noticing such details ;) No intentional offense Jeff! :) :) :) LOL!

Respectfully,
Henry

By Stephan (***)

Date 08-27-2009 18:51

Henry,

please don't get me wrong when I feel free to ask - I know you wouldn't! ;-)

How can we estimate about the arc energy without knowing somewhat about the electrical parameters chosen?

Surely, you're absolutely right when considering a higher thermal energy transfer for pure CO2 due to higher voltages - compared to similar peripheral conditions with Ar/CO2 mixtures. Nonetheless, at least in my very humble opinion ~ 690 MPa vs. ~ 500 MPa, just induced by 1.5... 2 Volts higher voltage?

Quite strange...

All the best,
Stephan

P.S. Forgive me, I have to leave the forum for today. My beloved wife is swinging the hammer right behind me, and she's doing this in a way that I am hardly reminded on a CV-Notch test!! :-)

See you tomorrow, friends!

By ssbn727 (*****)

Date 08-27-2009 19:22 Edited 08-28-2009 00:19

Good Afternoon Stephan!

That is Not the point I'm trying to make because, all I am trying to point out to you, and everyone else is the fact that the original poster of this thread is quoted in stating quote: "The lower readings were using a 90% argon 10% co2 the higher reading was using 100% co2. Would the gas make that much difference on the results?" When he stated this, he meant, quote: "the 2 test were ran, on 1 the ultimate unit stress, psi were in the 72900 range, on the other the results were in the 100000 range." Followed once again by this quote: "A514 materisl with 90thou wire. The only difference on these two test were the gas. The lower readings were using a 90% argon 10% co2 the higher reading was using 100% co2."

I am simply copying, and pasting the original poster's quotes verbatim in the hope to aid in stating my observation and not in effect, changing anything nor adding anything else to the very limited amount of information this poster gave us in seeking advice and finding an answer to his original query! :) :) :)

So even without having any prior knowledge to any of the specific welding parameters involved in which none of us are privileged to be aware of in the first place, and since the originating poster did only mention quote; "The only difference on these two test were the gas."

Then unless there was a substantial difference in the flow rate between the two gases, it is a well established fact that the greater amount of arc energy alone as a result of using 100% CO2 would provide for greater penetration, probably better fusion and probably a faster rate of travel speed if this is meant to be used for it's advantage other than one would notice if using a blend of 90% Argon and only 10% CO2 since the majority of this mix is an inert gas as opposed to a 100% reactive gas such as 100% CO2!!! Now this is assuming that the power source closed circuit current/voltage settings were identical when running the two samples on different shielding gases (which has subsequently been revised and shown as not being the case) via a second post from 52757, and then there's no mention at all in reference to the location as well as the orientation regarding the sample test coupons, the specific type of mechanical test performed.

So, Yes Stephan!!! I agree that we cannot "Estimate" what the arc energy would be...However, we can say in a purely theoretical sense that the arc energy transfer would probably be greater with CO2 by the very nature of 100%CO2 being a totally reactive gas compared to 90% Argon with a balance of only 10% CO2 which would have enough Argor to lower the Arc energy transfer substantially enough to inhibit fusion, penetration and most importantly promote enough acicular ferrite growth which would in turn provides the strength and ductility in Q&T steels like A514 instead potentially resulting in greater amounts of martensitic & bainitic chrystalline structures that basically increase hardness in the weld and adjacent HAZ but, since 52757 decided to inform us of more specific details with respect to some of the different parameter that were ACTUALLY used in his test, all of this hypothesisizing that occurred form all of us can be literally thrown out the proverbial window!!! :) :) :)

Now I hate to ASSUME as much as you do but, if I'm forced to assume with only the limited amount of information as is the case with this original post, then I'm going to place my bet on choosing the 100& CO2 gas for having a greater Arc energy transfer therefore, resulting in a higher ultimate unit stress value of 100,000 compared to the 72,900 from the use of 90% Argon with a balance of only 10% CO2 which is exactly what the poster originally posted!!! I realize gentlemen that I'm on a whole bunch of chemicals due to my various illnesses but, I know that I'm interpreting the original poster correctly as proven when I copy then paste his quotes for validation. Why nobody else can see what I am emphasizing has myself wondering just for an instant, whether or not I'm losing my mind - Nah... I do not think so!!!

Edited 6PM EST: Finally, please check the time frame (Time stamp of each post listed after each poster) from where 52757 decided to add so much more pertinent information which is what I am trying to point out to both you, Jeff, John and Larry because it wasn't until this person - 52757 added the fact that he used FCAW at different current/voltage parameters for each gas type that any of us knew in greater detail, or have a better understanding of why 52757 was getting such results as he stated in his original post without including ALL of the necessary data.

All I was trying to point out to ALL of you was the straightforward FACT that 52757 stated that he achieved higher ultimate unit stress results with the 100% CO2 of 100,000 as opposed to 72,900 with the use of 90% Argon - 10% CO2 mix... that's all!!! I also added that it was only my own opinion that without having ANY other necessary data available, the only thing that I could think of that could potentially account for the increased values with the use of 100% CO2 provided that all of the parameters were identical and as is the case, the reality is always different after the fact as 52757 initially neglected to include the subsequent information into the thread until after I had already noticed and sent all of you private messages that some of you may have been misreading the initial values that were initially posted by 52757 based on your initial responses especially when Jeff stated this which IMHO is irrefutable evidence that he was misinterpreting the original post:

"Even with the carburizing/oxidizing nature of CO2 I cannot believe that it would reduce the strength of the filler by 18ksi. This is over a 20% strength reduction. The carburizing would tend to make it stronger in general, and I doubt seriously the oxidizing would reduce low alloy content so much so as to cause this much strength reduction. I have never seen 100% CO2 reduce tensile strength like this in any alloy I have ever worked with." How could this statement be correct when the original poster states quite clearly (Although I must now question his own accuracy since reading his follow-up post!) when he states this: "The only difference on these two test were the gas. The lower readings were using a 90% argon 10% co2 the higher reading was using 100% CO2." So how can the previous quote - not post mind you, from Jeff make any sense and more importantly, now that we have all been provided with more logical details which in them selves are also questionable how can we trust that 52757 is being accurate in providing data that is also accurate???

It might make sense after 52757 included his second post at a much later time frame, but nonetheless, when only a limited amount of data was found in the initial post, it was misinterpreted - Plain and Simple, and if any of you guys cannot see that even now, then I strongly suggest that you all get your eyes checked!!! I know that I'm going to also but, I know what I can see, and I stand by it as well as my own computer's ability to copy and paste my point! I mean how can 100,000 be less than 72,900 if they are not "Signed" numbers??? CAPECHE??? THAT's MY POINT!!! ;) So now that we all know what little info 52757 is willing to share with us, I still do not put much validity into the numbers he's providing based on the fact that he - himself even admits that he's not quite sure of his own numbers!!! :( :( :( I guess more will be revealed after some time of reflection on the part of 52757! :) :) :)

Respectfully,
Henry

By Stephan (***)

Date 08-28-2009 12:01

Hello there, dear Henry!

First off, thanks a lot for spending your precious time for both writing such an outstanding response to myself but also contributing so much valuable information to the forum.

It was a MUST DO for me to say so.

It's a kind of blessing knowing extraordinary experts like Lawrence, Jeff - to keep it short - all the others, and of course last but by no means the least, YOU aside to be allowed learning from them.

Hmmm... Henry I must admit. My head is spinning by having read through all of that what's being contained in this interesting thread.

So now we know, it's FCAW we are talking about. Just as already correctly supposed by Lawrence.

But, as I am honestly way of being a shadow of an expert in FCAW of Q&T steels, I have honestly no idea of in how far the conditions, valid for solid wire GMAW - and always with respect to shielding gas influences - are transferable to FCAW. As you know, occupying myself with those physical coherences is one of my greatest passions and the physical ralations for solid wire GMAW are lightyears away of being fully understood. This, makes it difficult - but also interesting - enough.

What however I mean to know is, and please correct me when I'm wrong, that many things may be turned upside down when it comes to the influences of shielding gases in combination with FCW.

So far so good...

What my personal intention was, as I have ventured to reply on '52757's or Jeff's post respectively, that the spread between both values was such impressive. Furthermore it was hardly imaginable to me to just explain this leap in the mechanical property only by the - undoubted existing - differences in the influences between the shielding gas compositions stated by '52757'. Namely 100% carbon dioxide and 90Ar/10CO2.

So you know, my very first thought was - always under the consideration of that I had no idea of the materials' designations - eventually it could be a 'normal' statistical scattering as there were just two samples tested.

You know what I am moving to? Error bars... or in other words: Standard Deviation. I hope I'm right by saying that sometimes very strange values may come out when it goes around 'mechancial material testing'. That was also the reason that I have mentioned again the CVN-tests, the outstandingly appreciated Professor William Lucas of TWI has conducted in the UK at that time.

As far as memory serves correctly, they had deviations in their results which were that widespread that it was tremendous - to say the least - and entirely unexplainable on a first and second and third view.

And by investigating the reasons for even those scatterings were finally and at the end of a long long row of trials... the test houses conducting the CVN-tests and their way of preparing the samples in a correct manner!!

Coming to an end...

I just thought, that perhaps two samples were - simply put - too few samples, to obtain an appropriate and solid average judgement for the influence of those two different shielding gases. And twice as the distance between both values was even that high.

But like I said. That was just a very personal and humble interpretation.

Anyway. I would like to 100% agree with you as you have emphasized the crucial importance of data, when discussing tricky items like this one. :-)

I wish you very well and I promise to pursue this thread with also furthermore great interest!
Stephan

P.S. And once again I have to agree with Jeff, saying: "You ain't losin your mind." :-)

By Stephan (***)

Date 08-29-2009 18:28 Edited 08-29-2009 18:38

Henry,

I beg your forgiveness, but this topic didn't let my mind rest to piece.

Even though I'm not sure whether we may ever unravel this mystery treated here, I have tried to dig a bit deeper in terms of the materials both filler- and base material.

And as far as my research was almost correct, then the base material A 514(A) (I hope that was the right grade) has a tensile strength between 680 and 895 MPa (~ 98625 PSI... ~ 129808 PSI).

See also: http://www.matbase.com/material/ferrous-metals/low-temperature-steel/a514-a/properties

Hence, at least in my humble opinion, it may be rather unlikely that the failure has occurred in the unaffected base material.

Then I found a very informative and interesting company (Select Arc) in the www. They have an excellent product catalogue which shows that they are producing the wire '52757' has named in his second post. Namely 'E91T1-K2M'. And they have listed this particular wire, or its 'typical mechanical properties' within this catalogue.

I would like to attach this particular catalogue section hereinafter.

However, they have welded the wire under pure CO2 and 75Ar/25CO2, and have obtained excellent values for the ultimate tensile strength.

And the interesting with the results was that independently of which gas has been used, the values laid above 100,000 PSI (~ 690 MPa).

As I thus suppose that neither the base- nor the sound weld metal would have failed with ~ 73,000 PSI, please let me ask.

Could it eventually an interior flaw (slag inclusion, porosity,...) within the weld metal have been the cause for the 'low' value of 72,900 PSI?

Just a humble thought...

Thanks!
Stephan

EDIT: I've just corrected a literal error ;-)

By ssbn727 (*****)

Date 08-29-2009 22:21

Hello my friend Stephan!!! ;)

That is a possibility, and something to consider. ;) However, if we do not have any other relevant, pertinent info such as visual evidence, detailed testing data, and something that 52757 still overlooked to include in his second post; some missing essential & non-essential variables such as; travel speed, whether or not the welds were deposited manually or in a mechanized configuration, environmental conditions, joint configuration, thickness of the actual base/parent metal, actual base/parent metal chemical composition and probably some more relevant information that 52757 neglected for whatever reasons to include in both his initial query as well as in his second additional post.

So as far as I'm concerned, I'm not going to speculate any further until more data is provided by 52757. ;)

On another note Stephan, I just posted another addition of educational links as well as video's from You Tube covering metallurgy, material science, and steel making video's which I hope you will enjoy reviewing them at you leisure!!! :) :) :) You can find this post in the Metallurgy section of "The World's Greatest Welding Forum" ;)

http://www.aws.org/cgi-bin/mwf/topic_show.pl?tid=22316

Respectfully,
Henry

By Stephan (***)

Date 08-30-2009 09:31

Henry!

Quote:

"...However, if we do not have any other relevant, pertinent info such as visual evidence, detailed testing data (...) speed, whether or not the welds were deposited manually or in a mechanized configuration, environmental conditions, joint configuration, thickness of the actual base/parent metal, actual base/parent metal chemical composition and probably some more relevant information (...) I'm concerned, I'm not going to speculate any further until more data is provided..." .

Sir, yes Sir!

I mean this is 100% agreeable!

Thanks for your reasonable reply AND the bunch of information you have posted in the 'Metallurgy' section!

Good Lord! I'm just afraid that it will take the next several years to enjoy this!! :-)

Take care and all the best!
Stephan

By ssbn727 (*****)

Date 09-02-2009 22:15

Hi Stephan!

I was looking over this link the other day and I think it warrants another look with respect to this thread so ENJOY!!! ;)

http://www.msm.cam.ac.uk/phase-trans/2005/Graz/Graz.html

Respectfully,
Henry

By Lawrence (*****)

Date 08-27-2009 18:51

Henry,

You said
"one can most definitely agree that there is a substantial difference in arc energy being transferred when CO2 is used as the shielding gas when compared to 90% argon, and a balance of only 10% CO2 "

Again if we assume FCAW, I don't agree that we know about differneces in arc energy when comparing 90/10 with 100% CO2...

This is because of the many functions of the flux... Deoxidizing, arc stabilization, scavenging, alloying, arc stabilization and many more.

When a gas is being used that the electrode is not specifically designed for... Who can know what the results will be on things like arc energy, width of the plasma cone, depth of penetration and any number of other important factors that may have a direct bering on mechanical yeilds..

By ssbn727 (*****)

Date 08-27-2009 19:59 Edited 08-27-2009 20:02

Hi Lawrence!

So, you do not agree that 100% CO2 - which is a totally reactive or as the Europeans say: "active" gas, hence the term when used: "MAG" (Metal Active Gas) has a greater arc energy input than what amounts to an almost totally inert gas mix except for the fact that this mix also, and only has TEN PER CENT of Carbon Dioxide resulting in a far less amount of arc energy input in comparison regardless of any other factors, or parameters the original poster neglected to include in his original query... Don't you agree???

So please!!! Carefully, re-read the original post, then re-read my response, then let me know what you think. Thanks in advance!!! ;)

Respectfully,
Henry

By js55

Date 08-27-2009 19:43 Edited 08-27-2009 20:03

Henry,
OK. I will grant that my diabetic friend has far better eyes or more vigilant scrutiny than myself. But lets do it this way. If the CO2 is the stronger it still don't make any sense. A514 is a Q and T material which should mean that with higher real energy input and slower cooling rates the heat treated strength of the material should be reduced (the Q and T is gone and you essentially have a normalized microstructure). However, this would still only be the HAZ.
The reverse order of the gases as you correctly noted still does not explain a 28ksi difference in the filler metal results, which as I read it, was the same. But I'll go back and read it again. :)

PS: You ain't losin your mind. :)

By ssbn727 (*****)

Date 08-28-2009 04:59 Edited 08-28-2009 05:01

Hi Jeff!!!

I agree with your observation and I would like to take the opportunity to simplify what I think may be one of the reasons why the one sample which was welded with the 90% Argon - 10% CO2 mix... Acicular ferrite in order to prevent crack propagation - has to form or else, Martensite & Bainite will instead leaving the result of having a very hard and brittle sample. :) :) :) ( Please read my response to Stephan above which goes in depth about Acicular Ferrite. :) )

There's probably more unidentified possibilities involved but, since we've been "spoon fed" in a very erratic manner, some of the necessary details which would better explain what is going on, then we must remain adamant, and insist that if anyone else wants to post such a query in the future, then they better have as much data available if they even have the slightest notion of receiving a complete and comprehensive response!!!

I mean, it only takes maybe, five more minutes of time to include the data which was given later on instead of not considering the consequences of leaving out such critical information by proof-reading one's own post, and recognizing that MORE DATA IS NEEDED!!! ;) FUGGEDABOUDIT!!! :) :) :)
I know that I am going to. ;)

Respectfully,
Henry

By js55

Date 08-28-2009 12:58 Edited 08-28-2009 13:02

If I preface by saying that without looking it up I am not well versed in A514 microstructural evolutions but I suspect that a material that is designed for Q & T does not achieve martensite, or at least a very large volume fraction of it in a normalized HAZ (even though there will be some quench chilling from the BM). So again we are left with the weld metal. I have to doubt that what little difference in cooling rate would result from the differing energy levels from the gases(M, B, AF don't care about energy levels at the liquid stage only time at transformation temps when solid), given that amps/volts/TS are assumed equal, would be significant enough to effect microstructural constituent volume fractions enough for 28ksi.
I understand the possibility of the cooling rate sitting on the tip of a CCT diagram C-Curve and then shifting out of it for a comprehensive transformation variance, but this at best only causes me to agree with your point about needing more information not as yet admitting the gases are the cause.