Sulfuric acid is typically used for carbon and low-alloy steels. After the acid bath, the steel is rinsed in water. A low carbon steel having enough iron oxide to give a continuous evolution of carbon monoxide during solidification giving a rim of material virtually free of voids. An imperfection which is a flat piece of metal rolled into the steel surface. A defect on the surface of a metal which appears as a crack.
Experience indicates that most seams are created during the cooling or reheating of cast structures.
A special type of annealing that requires an extremely long cycle. This treatment is used to produce globular carbides and maximum softness for best machinability in some analyses, or to improve cold formability. The length is not determined by mold dimensions. A thermal treatment to restore elastic properties and to minimize distortion on subsequent machining or hardening operations. Normal practice would be to heat to a temperature 100 F lower than the tempering temperatures used to establish mechanical properties and hardness.