Inconel 718 Specification ASTM F2281 UNS N07718

This F2281 specification covers the chemical and mechanical requirements for stainless steel and nickel alloy bolts, hex cap screws, and studs, 1⁄4 in. diameter and larger, intended for use at temperatures up to 1800°F (982°C), and in applications where resistance to heat and the effects of high temperature are to be considered. A wide variety of materials are covered in this specification which can be used at high temperatures as a function of the specific alloy properties, as well as environmental requirements including corrosive environments.

Inconel 718 ASTM F2281 UNS N07718 Classification

Inconel 718 ASTM F2281 UNS N07718 Material And Manufacture

• Material:

Specifications A276, A484, A493, A564/A564M, A582/A 582M, B637 are noted for information only as suitable sources of material for the manufacture of bolts, hex cap screws, and studs to this specification.

The bolts, hex cap screws, and studs shall be manufactured from material having a chemical composition conforming to the requirements listed in Table 1 and capable of developing the mechanical property requirements listed in Table 2 for the finished fastener.

Various grades of material having unique heat resisting or high temperature characteristics are specified in this specification. A guide to their application is listed to assist in the selection of the fastener material.

The form and condition of the raw material shall be at the option of the manufacturer but shall be such that the finished fastener conforms to all the specified requirements.

• Manufacture:

Forming—Unless otherwise specified, the fasteners shall be cold formed, hot formed, or machined from suitable material, at the option of manufacturer.

Threads—Unless otherwise specified, the threads shall be rolled or cut, at the option of the manufacturer.

Condition—The fasteners shall be furnished in one of the following conditions and shall be agreed upon between the manufacturer and the purchaser at the time of the inquiry and order.

Inconel 718 ASTM F2281 UNS N07718 Chemical Composition

Chemical Composition—Bolts, hex cap screws, and studs shall conform to the chemical composition requirements prescribed in Table 1 for the specified alloy grade.

Product Analysis:
When a product analysis is made by the purchaser from finished fasteners representing each lot, the chemical composition thus determined shall conform to the requirements listed in Table 1 for the specified alloy grade, subject to the Product Analysis tolerance listed in Specifications A484 and B880.

In the event of a discrepancy, a referee chemical analysis of samples, taken from each lot, shall be made in accordance with 14.1 and 15.1.

Inconel 718 ASTM F2281 UNS N07718 Heat Treatment

Condition AH4—(Precipitation Hardened Alloy Type III Class C), shall be solution treated at 1725°F (941°C) to 1850°F (1010°C), held at the selected temperature for a time commensurate with cross-sectional thickness, and cooled at a rate equivalent to an air cool or faster. Solution treating temperatures shall be controlled in a range of ±25°F (±14°C). Precipitation Hardening (Aging) shall be performed by heating to 1325°F (718°C) held at heat for 8 h, cooled to 1150°F (621°C) at a rate of 100°F (56°C) per hour, held for 8 h at heat and air cooled. Alternatively, parts may be furnace cooled to 1150°F (621°C) at any rate provided the time at 1150°F (621°C) is adjusted so the total heat treat time is 18 hminimum. Precipitation treatment temperatures and cooling rates shall be controlled in the range of 615°F (±`8°C).

Inconel 718 ASTM F2281 UNS N07718 Mechanical Properties

Bolts, hex cap screws, and studs shall meet the applicable mechanical properties listed in Table 2 for the specified alloy grade and condition when tested at room temperature, in accordance with the mechanical properties requirements specified herein for the type, grade, diameter, and length.

Mechanical Test Requirements:
8.2.1 Bolts and hex cap screws which meet the minimum requirements for length, and have a maximum 160 000 pound tensile load, shall have a full size wedge tensile strength and yield strength test performed as outlined in Section 15. For bolts and hex cap screws which exceed the 160 000 pound limit, a Machined Specimen tensile strength, yield strength, and elongation test performed as outlined in Section 15 may be substituted for the full size wedge test. In addition, for bolts and hex cap screws that are less than the minimum length requiring tension tests, either a full size wedge tensile strength test, full size axial tensile strength test or a Rockwell hardness test shall be required as outlined in Section 15. In all cases, full size wedge tensile strength testing shall be performed whenever possible.

Studs which meet the minimum requirements for length and have a maximum 160 000 pound tensile load, shall have a full size axial tensile strength test and yield strength test performed as outlined in Section 15. For studs which exceed the 160 000 pound limit, a Machined Specimen tensile strength, yield strength, and elongation test performed as outlined in Section 15 may be substituted for the full size axial test. In addition, for studs that are less than the minimum length requiring tension tests, either a full size axial tensile strength test or a Rockwell hardness test shall be required as outlined in Section 15. In all cases, full size axial tensile strength testing shall be performed whenever possible.

In the event of a discrepancy between full size wedge test, full size axial test, machined specimen test, and Rockwell hardness test results, the precedence sequence shall be the same as the sequence listed in this section for acceptance purposes. That is, if parts pass axial tensile but fail Rockwell hardness they are acceptable; however, if they fail axial tensile and pass Rockwell hardness they are not acceptable.

If tests to determine high temperature properties are required on Type III High Temperature Alloys, supplementary requirement S8 shall be specified in the inquiry and order and high temperature testing shall be performed and meet the applicable mechanical properties listed in Table 3.

Inconel 718 ASTM F2281 UNS N07718 Mechanical Property Requirements at Room Temperature

Inconel 718 ASTM F2281 UNS N07718 Elevated Temperature Mechanical Property Requirements for Type III High Temperature Alloys

Inconel 718 ASTM F2281 UNS N07718 Corrosion Resistance

Carbide Precipitation:
The type I, class A austenitic alloys listed in 4.1.1.1 and all type II austenitic alloys listed in 4.1.2 shall be capable of passing the test for susceptibility to intergranular corrosion in accordance with Practice E of Practices A 262. 9.1.2 As stated in Practices A 262, samples may be subjected to the faster and more severe screening test in accordance with Practice A. Failing Practice A, specimens may be tested in accordance with Practice E and be considered satisfactory if passing Practice E.

Inconel 718 ASTM F2281 UNS N07718 Dimensions

Bolts and Hex Cap Screws:

• Unless otherwise specified, the dimensions shall be in accordance with the requirements of ASME B18.2.1 for Hex Cap Screws.
• When specified, the dimensions of bolts shall be in accordance with the requirements of ASME B18.2.1 (type as specified), or such other dimensions as shall be specified.

Studs:

• Dimensions of studs shall be specified by the purchaser.

Stud Type:

• Continuous thread.
• Double end clamping (also known as stud bolt or bolt stud).
• Double end interference (also known as tap-end stud).
• Other studs as shall be specified by the purchaser.

Threads—Unless otherwise specified, studs shall have Class 2A threads in accordance with ASME B1.1.

Points—Unless otherwise specified, the points shall be flat and chamfered or rounded at the option of the manufacturer.

Inconel 718 ASTM F2281 UNS N07718 Corrosion Resistance

ASTM Standards:

A262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels.
A276 Specification for Stainless Steel Bars and Shapes.
A342/A342M Test Methods for Permeability of Feebly Magnetic Materials.
A380 Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems.
A484/A484M Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings.
A493 Specification for Stainless Steel Wire and Wire Rods for Cold Heading and Cold Forging.
A564/A564M Specification for Hot-Rolled and Cold- Finished Age-Hardening Stainless Steel Bars and Shapes.
A582/A582M Specification for Free-Machining Stainless Steel Bars.
A751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel Products.
B637 Specification for Precipitation-Hardening Nickel Alloy Bars, Forgings, and Forging Stock for High-Temperature Service.
B880 Specification for General Requirements for Chemical Check Analysis Limits for Nickel, Nickel Alloys, and Cobalt Alloys.
D3951 Practice for Commercial Packaging
E21 Test Methods for Elevated Temperature Tension Tests of Metallic Materials.
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications.
E76 Test Methods for Chemical Analysis of Nickel-Copper Alloys.
E139 Test Methods for Conducting Creep, Creep-Rupture, and Stress-Rupture Tests of Metallic Materials.
E292 Test Methods for Conducting Time-for-Rupture Notch Tension Tests of Materials.
E353 Test Methods for Chemical Analysis of Stainless, Heat-Resisting, Maraging, and Other Similar Chromium-Nickel-Iron Alloys.
E354 Test Methods for Chemical Analysis of High-Temperature, Electrical, Magnetic, and Other Similar Iron, Nickel, and Cobalt Alloys.
F606 Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, and Rivets.
F788/F788M Specification for Surface Discontinuities of Bolts, Screws, and Studs, Inch and Metric Series.
F1470 Guide for Fastener Sampling for Specified Mechanical Properties and Performance Inspection.