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