Carbon steel flat bar is one of the most widely used materials on the planet. You'll find rectangular bar in everything from building construction to household appliances. We carry carbon steel flat bar in A36,1018,1045,1075, 1084,1095, 11L17, 15N20,26C3, 52100, and 80CrV2. Most cold-rolled steel flat bar stock is available in full-size and custom-cut lengths.