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 specification covers alloy-steel bolting material specially heat treated for high-temperature service, such as steam turbine, gas turbine, and similar uses. This material requires special processing and should not be used in general-purpose applications. The term "bolting material," as used in this specification, covers rolled or forged bars, bolts, nuts, screws, washers, studs, and stud bolts. The bars shall be hot wrought. The material may be further processed by centerless grinding or by cold drawing.

1.2 The high-temperature properties of the material 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 material. Note 1High-temperature tests shall not be required, unless made a matter of agreement between the manufacturer and the purchaser.

1.3 Three levels of bolting strength are covered, designated Grades B4B, B4C, and B4D. Selection will depend on the design and the stresses and service for which the product is to be used. Note 2When ordering material under this specification, or when incorporating this specification as a reference in any individual specification, the purchaser must designate the steel by identification symbol or analysis, or both, and definitely specify the minimum mechanical properties required as selected from .

1.4 Supplementary requirements of an optional nature 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.

1.5 This specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable "M" specification designation (SI units), the material shall be furnished to inch-pound units.

1.6 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.