This specification covers a precipitation hardening bolting material (UNS N07718) for high temperature service. The alloy shall be multiple melted using consumable electrode practice in the remelt cycle or shall be induction melted under vacuum. Requirements for solution treatment, precipitation heat treatment, straightening, and thread forming by rolling are detailed. Remelt ingots shall conform to the chemical composition requirements (as to chemical and product analyses) prescribed for the following elements: carbon, manganese, silicon, phosphorus, sulfur, chromium, cobalt, molybdenum, columbium, titanium, aluminum, boron, iron, copper, and nickel. Tensile, hardness, and stress rupture tests shall be performed and test specimen shall meet the requirements specified for tensile strength, yield strength, elongation, Brinell hardness, and stress rupture. The method of determining the minimum full size breaking strength for headed fastener is given. Metallography shall be taken for microstructure and macrostructure properties including grain size and flow lines.

1.1 This specification covers precipitation hardening bolting (UNS N07718) for high temperature service. See Specification for the definition of “bolting.”

1.2 The following referenced general requirements are indispensable for application of this specification: Specification .

1.3 Supplementary requirements are provided for use at the option of the purchaser. The supplementary requirements only apply when specified individually in the purchase order or contract.

1.4 This specification is expressed in both inch-pound and in SI units. However, unless the purchase order or contract specifies the applicable M designation (SI units), the inch-pound units shall apply.

1.5 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.