Oil - Applied after pickling or temper rolling to assist customer handling by minimizing inter-wrap gouging, improve lubricity and provide a more rust resistant product.

Oiled Sheet - Sheet product that is processed with the final step being the application of oil to the surface. Usually, the oil is intended to provide protection from rusting during shipment and storage. These oils are called rust-preventative oils. The oil may also serve to assist in the subsequent fabrication process, but this is not usually the main purpose.

Oils used to enhance formability are often called prelubricants or "prelubes".

Olsen Ductility Test - A cupping test in which a piece of sheet metal, restrained except for the center, is deformed by a standard steel ball until fracture occurs. The height of the cup in thousandths of an inch at time of failure is a measure of the ductility.

Open Hearth Process - One of the main methods used in the production of steel from hot metal (iron) produced in the blast furnace. The furnace can be charged with hot metal, and cold steel scrap for further refining into a carbon or alloy steel. Generally open hearth furnaces range from 75 to 450 tons of melting capacity in one heat.

Oxidation - The addition of oxygen to a compound. Exposure to atmosphere sometimes results in oxidation of the exposed surface, hence a staining or discoloration. This effect is increased with temperature increase to the point where heavy scale is formed and the steel product has a decarburized surface.