【国外标准】 Standard Specification for Stainless and Alloy-Steel Turbine-Type Bolting Specially Heat Treated for High-Temperature Service

This specifications covers alloy-steel bolting material specially heat treated for high-temperature service, such as steam turbine, gas turbine, and similar uses. The grades of steels covered here are: Grade B4B, Grade B4C, and Grade B4D. Steels of Grades B4B and B4C shall undergo heating, liquid quenching, reheating, tempering, and air or furnace cooling, respectively. Steels of Grade B4D shall undergo heating, oil quenching, reheating or tempering, and air of furnace cooling, respectively. Heat and product analyses shall be performed wherein specimens shall conform to required chemical composition of carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, vanadium, tungsten, aluminum, titanium, and tin. The steels shall undergo tensile, impact, and hardness tests, and shall conform to the following mechanical requirements: tensile strength, yield strength, elongation, impact value, Brinell hardness number, and Rockwell hardness number. All bars or forged blanks of starting material shall be subjected to nondestructive inspection using any of the following methods: Eddy current, Magnetic particle inspection (wet or dry), Liquid penetrant inspection, Ultrasonic testing, or Visual testing.1.1 This specification2 covers stainless and alloy-steel bolting material and bolting components specially heat treated for high-temperature service, such as steam turbine, gas turbine, and similar uses. See Specification A962/A962M for the definition of bolting. This material requires special processing and should not be used in general-purpose applications. Bolting furnished as bars shall be hot wrought and may be further processed by centerless grinding or by cold drawing.1.2 The high-temperature properties of the bolting materials and components covered by this specification are dependent upon special heat treatment, which is required. Although the high-temperature properties are not specified, they are implied by control of the chemistry, heat treatment, and room-temperature properties of the bolting material.1.3 Three levels of bolting strength are covered, designated Grades B4B, B4C, and B4D.1.4 The following referenced general requirements are indispensable for application of this specification: Specification A962/A962M.1.5 Supplementary requirements are provided for use at the option of the purchaser. The supplementary requirements shall apply only when specified individually by the purchaser in the purchase order or contract.1.6 This specification is expressed in both inch-pound units and in SI units; however, unless the purchase order or contract specifies the applicable M specification designation (SI units), the inch-pound units shall apply.1.7 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. 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.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.