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ASTM standard - an international institute based in the United States ( ) describing specifications for Ductile Iron Castings.

Abstract from the standard description in the institute web site:
This specification covers ductile iron castings, also known as spheroidal or nodular iron, that is described as cast iron with the graphite substantially spheroidal in shape and essentially free of other forms of graphite. Appropriate heat treatment shall be identified according to grades, as follows: a full ferritizing anneal for 60-40-18; a quench and temper, or normalize and temper, or isothermal heat treatment for 100-70-03 and 120-90-02; and as-cast for 65-45-12 and 80-55-06. Castings shall be tested and conform to specified tensile requirements such as tensile strength, yield strength, and elongation. When indicated in the contract or purchase order, castings shall also adhere to special requirements like hardness, chemical composition, microstructure, pressure tightness, radiographic soundness, magnetic particle inspection dimensions, and surface finish.

Description of the standard on the ASTM website (download fee)

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