Oil Quench - A quench from the hardening temperature, in which oil is the cooling medium.
Olsen Test - This is a cupping test made on an Olsen machine as an aid in determining ductility and deep drawing properties. The test simulates a deep drawing operation. It is continued until the cup formed from the steel sample fractures. Ductility and drawing properties are judged by the depth of the cup, position of the break, condition of the surface after the break, etc.
Out-of-Round - The difference between maximum and minimum diameters of a bar measured at the same cross-section.
Out-of-Square - The difference between two dimensions of a square bar, each dimension being the distance between opposite sides and both measured at the same cross-section.
Overheating - Heating to such a temperature that, while the properties of the metal are impaired, it has not been burned and can therefore be rendered by heat-treatment.