the other day me and john were in the shop and we were going to make some christmas presants (knifes). i had an old cultivator blade and was straightining it out and all of a sudded it cracks while it is red. just wondering if it is actually wrought and if so what can i do with it?...thanks, Quentin

probably not wrought iron but old steel can have some of the same problems ...can you forge weld? might fold it and forge weld it .. or grab a new piece of steel and start over ..

I'm not a competent, but I don't think it is wrought iron... If it brakes for you it brakes for the blacksmith in the past... It can be cast iron maybe...
Try forging it at a higher temperature, and maybe it won't brake...
I hope i've said something correct and useful. :)

Could be high sulfur steel. High sulfur creates a condition known as "hot shortness" where the sulfur collects at grain boundaries and can cause cracks at elevated temperatures.

I can't be sure if this is the same problem, but I've cracked a cultivator blade before from forging it at a dark red. Maybe try forging it at a higher temperature (somewhere around orange).

Have you tried a spark test?

i misspoke it was not red but it was orange... it didnt break off all the way, just had big cracks

yes, john did do a spark test, but he said he thought it was wrought also, i dont know what the results were on the spark test though.