Inconel 718 is primarily governed by several ASTM standards that outline its composition, properties, and applications. The most relevant ASTM standards for Inconel 718 are:
1. ASTM B637 – Standard Specification for Inconel 718® Alloy (UNS N07718)
Description: This standard defines the specifications for Inconel 718 alloy, which is a high-strength, corrosion-resistant nickel-chromium alloy.
Applications: Used for high-temperature applications in industries such as aerospace, chemical processing, and turbine engines.
2. ASTM B670 – Standard Specification for Inconel 718® (UNS N07718) Sheet, Strip, and Plate
Description: Covers the requirements for sheet, strip, and plate forms of Inconel 718, ensuring proper dimensional tolerances, mechanical properties, and heat treatment conditions.
3. ASTM B637/B637M – Standard Specification for Nickel-Chromium Alloys for High-Temperature Service
Description: Provides the standards for Nickel-Chromium alloys, including Inconel 718, used in applications requiring high strength, oxidation, and corrosion resistance at elevated temperatures.
Grade: Inconel 718 falls under this specification for alloys designed for high-temperature environments.
4. ASTM A276 – Standard Specification for Stainless Steel Bars and Shapes
Description: While this standard is primarily for stainless steel, it can sometimes apply to Inconel 718 in bar forms (for specific conditions or as a reference standard for bar products).
5. ASTM A312 – Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes
Description: While it is primarily aimed at stainless steels, some nickel-based alloys like Inconel 718 can fall under similar processing standards for pipes and tubes.
6. ASTM F3059 – Standard Specification for Nickel-Chromium Alloys for Welding
Description: Covers alloys for welding, including Inconel 718, used in applications where high-temperature performance and resistance to oxidation are critical.
Key Properties Covered in These Standards:
Composition: Ni (50-55%), Cr (17-21%), Mo (2.8-3.3%), Ti (0.65-1.15%), Al (0.2-0.8%), and others in trace amounts.
Mechanical Properties: High yield strength, tensile strength, and excellent fatigue and thermal-fatigue strength.
Corrosion Resistance: Superior oxidation and corrosion resistance in harsh environments, including in sea-water and chemical applications.
Heat Resistance: Capability to withstand temperatures up to 1300°F (700°C) and still maintain good mechanical strength.
These ASTM standards ensure the proper quality control, processing, and performance characteristics of Inconel 718 for various industrial applications.
