AAR Manual of Standards and Recommended PracticesCouplers and Freight Car Draft ComponentsM-201STEEL CASTINGSSpecificationM-201-00Adopted: 1923; Revised: 1984, 1993, 20001.0SCOPEThese specifications cover carbon and alloy steel castings for locomotive and car equipment and for miscellaneous use graded as A, B, B+, C, D, and E. AAR Specification M-201 provides for all cast-ings unless another AAR specification for a particular product provides for a variation.2.0BASIS OF PURCHASEGrade A castings shall be furnished unannealed, annealed, or normalized unless otherwise speci-fied by the purchaser. Grades B and B+ castings shall be furnished normalized or normalized and tempered. Grade C castings shall be furnished normalized and tempered or quenched and tem-pered. Grades D and E castings shall be furnished quenched and tempered.2.1At the purchaser’s request, a certification will be made the basis of acceptance. The certifica-tion shall include a statement that the material has been manufactured, sampled, tested, and inspected in accordance with, and meets the requirements of, all applicable provisions of these specifications. Each certification furnished shall be signed by an authorized agent of the supplier or manufacturer.3.0RECORDSThe manufacturer shall maintain for 15 years records of the mechanical and chemical test reports covering the heats representing the purchased castings. These records will be made available to the purchaser upon request.MANUFACTURE4.0PROCESSThe steel may be made by one or more of the following processes: Open hearth, electric furnace, crucible, converter, or basic oxygen.5.0HEAT TREATMENTCastings shall be cleaned sufficiently to respond to heat treatment. Internal cavities shall not be blocked by molding material. They shall then be treated according to the following procedure appropriate to the requirements of paragraph 2.0.5.1Heat Treatment5.1.1After pouring, castings shall be allowed to cool to a temperature below 1,000 °F (538 °C) prior to heat treatment at a rate that will not be injurious to the castings.5.1.2Full AnnealingThe casting shall be heated to the proper temperature above the transformation range for the required time to achieve complete austenization and to refine the grain structure. The casting shall then be allowed to cool slowly in the furnace. Unless otherwise required by the purchaser, the manufacturer has the option of normalizing instead of full annealing, where full annealing is spec-ified.5.1.3Normalized steel castings shall be processed in the following order:5.1.3.1Heat to the proper uniform temperature above the transformation range and hold for the proper time to achieve complete austenization and to refine the grain structure.5.1.3.2Withdraw from the furnace and cool in still air until temperature is below 700 °F (371 °C).B–47/1/00
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