[Munkul]

I think that's CEP's friend from Ireland. Somewhere awhile back it was suggested that the 6013 used in Ireland/Europe is a different rod than than the 6013 used in N. America. This makes some sense since the 6013 designation comes from the AWS not the IWS. In CEP's break tests with 6013 it broke in only 3 or 4 blows if I recall. 7014 was 12 or 13 blows I think.

I think this is right. 6013 has a very very wide range of rod types over here... they range from shallow penetration sheet metal rods, all the way to semi cellulosic structural and pipe rods with high impact properties.

The average 6013 is the general purpose rod over here. Good quality Esab, Bohler or Lincoln rods will do most jobs.

I don't run all that much rod, but I've been taught to keep a bit of arc length with 6013, not a long arc but longer than with 7018, which I would always drag along, or even slightly push into the joint. Still with a drag angle though.

 

[Munkul]

This is not a case of exponential increase. Exponential functions generally are of the form k•a^x, where k may be a constant, a is the base, and x is the exponent as a variable. The function you are describing, when something is being squared, where the exponent is a fixed "2", is called quadratic. Exponential functions have a specific meaning; we cannot simply say that because it has an exponent, and the exponent is "2" that it makes it "exponential".

This is a good point. It's a trap that I always fall into, to call a quadratic function an exponential function. It is, of course, an exponent, but when we refer to an exponential function, the exponent is a variable dependant on progression, not a fixed term.

Anyway, it;s been an interesting thread... sorry the science has went over the heads of some

 

[Munkul]

ETA: Merriam's agrees with me more than with you use re: usage of "exponential."
https://www.merriam-webster.com/dictionary/exponential

What we may have here, rhetorically, is "a distinction without a difference."
But thanks for playing.

There is a difference. A quadratic function or cubic function has a fixed exponent, 2 or 3 respectively.
An exponential function has a variable exponent.
As you point out: In short: Every quadratic is exponential. But not every exponential is quadratic.

involving a variable in an exponent:
10x is an exponential expression

They are not mutually inclusive events. So I'd say there is a distinct difference