Just learned something about wrought iron that threw me off

I was reading an old blacksmithing guide from 1892 I found at a flea market outside Pittsburgh, and it says real wrought iron has a tensile strength of about 50,000 PSI, way higher than I figured. Turns out most of the 'wrought iron' we buy today is actually just low-carbon steel with a fancy name. Has anyone else run into this fake stuff messing up their projects?

3 comments

3 Comments

milestaylor1mo agoMost Upvoted

Whoa that's wild, I actually just read something about this the other day. There was this old article from a metalworking blog that said the silica slag in real wrought iron forms these long fibers that basically work like rebar inside the metal. And @ruby_patel27 is totally right about the puddled iron thing, I remember reading that by the late 1800s a lot of places were already mixing in steel scraps because the traditional process was too slow. That fake stuff they sell now is just rolled steel with a surface texture painted on, it doesn't have any of that internal structure. No wonder your gate project failed, the modern stuff probably has half the tensile strength and none of the corrosion protection from the slag. It's a shame because you can't even get the real thing anymore unless you find salvage from old buildings or bridges.

morgan_ramirez1mo ago

Actually ran into that same problem trying to restore a 1910 farm gate in Ohio. The modern "wrought iron" from the big box store bent like butter under half the weight the original held for 80 years.

ruby_patel271mo ago

Actually @morgan_ramirez you might want to double check if that gate was actually wrought iron. Most old farm gates from that era were made from puddled iron or early mild steel. Real wrought iron hasn't been commercially produced in the US since the 1920s. The stuff they sell now as "wrought iron" is almost always just low carbon steel which is way softer and weaker. The original gate probably had a lot more silica slag worked into it, which gave it that extra strength and rust resistance. Have you checked the grain structure on the old gate or looked for those telltale slag lines?