Well...Certainly,there are parameters...Cultural(how precision-oriented were they);Geographical-what type of ores were involved,and what fuel was used to produce iron from it.
(remember,it took the Brits a Very long time to learn to use mineral coal,and Much very weird metal was produced meanwhile).
The parameters of specific purpose,for just how critical an application?(Eiffel tower is all WI,probably fairly nice stuff,too
People made iron in SO many different ways...In remote Scandinavia rural smiths freely controlled the C in their iron:If too much,they decarbed it right in their forge,not enough-they went the other way,enriching it,then quenching the carburised exterior(in the snow sometimes,it is said
) and chipping off flakes of resultant steel to be welded together into an edge of something...
Iron was made Everywhere,and freely imported/exported among places,and mixed in batches and exported elsewhere...
So predictability would be tough.
I am trying to paint the Entire picture admittedly.In practice,one Does run into less forgeble material at times,and less often-into nearly un-forgeble.
(i have a few bridge timber bolts from the gold prospects up the Innoko river,they're wholly unworkable,at any temperature
Many don't realise that behind the whole myth of excellence of Japanese steelmaking(especially as relates to nihonto)lies the simple fact that they had Very poor quality ores,very difficult to work with.
Eventually after much time and skill building they did get on top of it,but often employing complex mechanical constructions of the object to offset the problems with material itself.
So when a connoisseur sits down to admire the sword surface,(wearing their special cotton gloves and with the light falling just So),there at some 10s of thousands of grit polish,just like with polished wood the illusion of seeing Inside material occurs(of course it's just surface).But what they see there,and gaze at for a long time,is the multitude of particles of different contaminants,and variations of structure,and all sorts of wonders of (essentially dirty)metallurgy
.
Many people throughout history,especially early on,forged meteoritic iron.There must be tons and tons of it in circulation still,somewhere,farming implements,all kinds of stuff
There's still a big fat meteorite at the temple at Parambanan,and by applying for a royal decree a particularly deserving empu(a master-smith) may obtain a fraction,for a particularly worthwhile project...
I'mSoSharp or i would be Greatly puzzled if we got into a piece of scrap containing 7+% Nickel(and God only knows what else!