Newbie problem with O-1 steel in Problem Solving Posted May 8, 2016 Up until today I have been hammering on leaf springs, coils springs, etc. Today I started playing with known metals (wrought iron and O-1 steel). They both cracked on me during hammering. 1. I took a wrought iron rod, flattened it into a flat strip about 3/16" thick, and tried to bend it around a 2-inch diameter pipe with some gentle taps. It cracked. What did I do wrong? Did the iron cool too quickly while in contact with the pipe? 2. I bought some O-1 steel (3/8" x 1" rectangular bar). It cracked just hammering to thin it (see photo). The piece in the photo is still 1/4" thick. Was I working it too hot or too cold?