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| ASTM A668 / A668M Standard Specification for Steel Forgings, Carbon and Alloy, for General Industrial Use | |
| This specification deals with the standard requirements for untreated and heat-treated carbon and alloy steel forgings for general industrial use. This specification covers six classes of carbon steels (Class A to F) and seven classes of alloy steels (Class G, H, and J to N). Materials shall be forged by hot mechanical work. Except for Class A, all forgings shall be heat treated, depending on class, by the following techniques: annealed, or normalized, or normalized and tempered (Classes B, C, D, and G); normalized and tempered, or double-normalized and tempered (Class E); quenched and tempered, or normalized, quenched, and tempered (Classes F); normalized and tempered (Class H); normalized and tempered, or normalized, quenched, and tempered (Class J); and normalized, quenched, and tempered (Classes K, L, M, and N). Steel specimens shall undergo heat and product analyses, and shall conform to required chemical compositions for manganese, phosphorus, and sulfur. Steel forgings shall also be tested on their conformance to the following tensile requirements: tensile strength, yield point, yield strength, elongation, reduction of area, and Brinell hardness. | |
| 1. Scope | |
1.1 This specification covers untreated and heat-treated carbon and alloy steel forgings for general industrial use. Other ASTM specifications for forgings are available for specific applications such as pressure vessels, railroad use, turbine generators, gearing, and others involving special temperature requirements. 1.2 Hot-rolled or cold finished bars are not within the scope of this specification. 1.3 Six classes of carbon steel and seven classes of alloy steel forgings are listed (see Section 7) , which indicates their required heat treatments, as well as mechanical properties. 1.4 Provision, with the suffix H for certification and marking, for the supply of forgings after hardness testing only. 1.5 Supplementary requirements, including those in Specification A788/A788M, of an optional nature are provided. These shall apply only when specified by the purchaser. 1.6 Appendix X1 lists the current classes corresponding to the various classes of Specifications A235, A237, and A243, which have been superseded by this specification. 1.7 The values stated in either inch-pound units or SI units are to be regarded separately as the standard; within the text and tables, the SI units are shown in brackets. The values stated in each system are not exactly equivalent; therefore; each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. 1.8 Unless the order specifies the applicable "M" specification, the forgings shall be furnished to the inch-pound units. |
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| 2. Referenced Documents | |
A275/A275M Practice for Magnetic Particle Examination of Steel Forgings |
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| Index Terms | |
| alloy steel forgings; carbon steel forgings; general industrial applications; heat treatment classifications; strength classifications; Alloy steel forgings--specifications; Carbon steel forgings--specifications; Forgings--specifications; Industrial forgings--specifications; | |
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