1.1 This specification covers carbon steel, alloy steel, and martensitic stainless steel castings that are to be subjected to higher mechanical stresses than those covered in Specification A27/A27M. 1.2 Several grades of steel castings are covered, having the chemical composition and mechanical properties prescribed in Tables 1 and 2. 1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.3.1 Within the text, the SI units are shown in brackets. This specification covers the standard for carbon steel, alloy steel, and martensitic stainless steel castings that are to be subjected to higher mechanical stresses. All castings shall undergo heat treatment either by full annealing, normalizing, normalizing and tempering, or quenching and tempering and shall be regulated under pyrometers. Several grades of steel castings are covered and shall conform to the required chemical composition for sulfur and phosphorus. A tension test shall be performed and shall conform to the required tensile strength, yield point, and elongation. The notch bar impact properties shall also be determined by testing one set of three Charpy V-notch im