Machinability - The relative ease of machining a metal. Machinability index for various steels and machinability tables are available for comparing machining rates with 1212 steel as the standard for carbon and alloy steels and W-l as a standard for tool steels.

Martensite - A microconstituent or structure in quenched steel, which has the maximum hardness of any of the structures resulting from the decomposition or transformation of austenite. Steel which is to be quenched and tempered properly must first be fully hardened in the martinsitic state and then drawn or tempered back.

Mechanical Properties - The properties of a material that reveal its elastic and inelastic behavior when force is applied, thereby indicating its suitability for mechanical applications.

Mill Edge - The edge of strip, sheet or plate in the as rolled state. Un-sheared.

Modulus of Elasticity - The ratio within the limit of elasticity of the stress to corresponding strain. The stress in pounds per square inch is divided by the elongation in fractions of an inch for each inch of the original gauge length of the specimen. The dulus of elasticity for cold rolled steel is 29,500,000 psi and for other steels varies between 28,600,000 and 30,300,000 psi.