What ASTM B670 Covers
B670 covers rolled plate, sheet and strip in one alloy, UNS N07718, supplied in the annealed temper. The title describes it as precipitation-hardening nickel alloy for high-temperature service.
- Chemical requirements, including niobium (columbium), titanium, aluminium and boron.
- Tensile strength, yield strength and elongation, tested after the material has been precipitation hardened.
- Stress-rupture testing according to the referenced ASTM methods.
This is our own summary of the scope, not the standard itself. The current edition from ASTM sets the full requirements.
Why B670 Material Is Bought Annealed
Alloy 718 gets its strength from a niobium-rich gamma double prime precipitate formed during an ageing treatment. Sheet and plate are easier to form, cut and weld in the soft annealed state, so B670 material is supplied annealed and the purchaser ages the finished part. The specification proves the material will meet its properties by testing samples after they have been precipitation hardened.
Other Specifications for Alloy 718 Flat Products
Aerospace buyers usually order 718 sheet and plate to AMS 5596, and bar and forgings to AMS 5662 and 5663 or ASTM B637. Scrap marked with any of these is still N07718. See AMS specifications.
| Product form | Specification |
|---|---|
| Plate, sheet and strip | ASTM B670; AMS 5596 |
| Bar and forging stock | ASTM B637 |
| Bar and forgings | AMS 5662 (solution treated), AMS 5663 (solution treated and aged) |
What B670 Means for 718 Plate and Sheet Scrap
Most Alloy 718 scrap is turnings from forged parts, but flat-product scrap also arrives: sheet trim and skeletons from aero-engine fabrication, and plate drops from cut-to-size stockists. Marked B670 or AMS 5596 material is easy to prove. Because the sheet is often aged after forming, finished-part trim may be harder than mill offcuts, but the chemistry is the same.
- Photograph marks showing B670 or AMS 5596, N07718 and the heat number.
- Keep 718 flat scrap apart from 625 and Waspaloy, which are often fabricated in the same shops.
- Remove protective film and masking where possible.
More: Inconel 718 scrap.
ASTM B670 FAQ
What does ASTM B670 cover?
Rolled plate, sheet and strip in precipitation-hardenable Alloy 718, UNS N07718, in the annealed condition for high-temperature service.
Is B670 material supplied aged?
No. It is supplied annealed. Mechanical properties are checked on samples after precipitation hardening.
What is the aerospace equivalent of B670?
Aerospace 718 sheet, strip and plate is commonly bought to AMS 5596.
Is Alloy 718 plate scrap worth more than turnings?
Usually yes: solids carry no oil or moisture and are easier to prove by marking, so they are valued above turnings of the same grade.
Sources and Review
Figures are quoted as published in these sources; any value we could not confirm has been left out.
- ASTM International, B670 Standard Specification for Precipitation-Hardening Nickel Alloy Plate, Sheet, and Strip for High-Temperature Service (B670-25): title, abstract and scope as listed in the ASTM store.
- Inconel 718 specifications as published on this site.
Reviewed by Mitesh Shah, Proprietor, Mipra Steel · Published by Mipra Steel, Khetwadi, Mumbai · Last updated