What ASTM B446 Covers
B446 is the rod and bar specification for Alloy 625 and two related nickel-chromium-molybdenum alloys:
- UNS N06625, Alloy 625 (nickel-chromium-molybdenum-niobium).
- UNS N06219, nickel-chromium-molybdenum-silicon alloy.
- UNS N06650, nickel-chromium-molybdenum-tungsten alloy.
It applies to hot-worked and cold-worked product. N06219 and N06650 are supplied solution annealed only; Alloy 625 has three grades.
This is our own summary of the scope, not the standard itself. The current edition from ASTM sets the full requirements.
B446 Grades for Alloy 625
| Grade | Condition | Intended service |
|---|---|---|
| Grade 1 | Annealed | Service up to 593°C (1100°F) |
| Grade 2 | Solution annealed | Service above 593°C where creep and rupture resistance is needed |
| Grade 3 | Solution annealed and cold worked | Applications needing higher strength |
Grade 3 is the newer, higher-strength condition. For scrap, all three grades are Alloy 625 and are traded together once the alloy is proven.
ASTM B446 and ASME SB-446
Bar for pressure-equipment use is certified to SB-446, the ASME adoption of B446, and is frequently dual-marked. Valve bodies, stems, studs and flanges machined from such bar are a common source of 625 turnings and bar ends. See ASME SB and SA specifications.
What B446 Means for Bar-End and Turnings Scrap
Bar is where most Alloy 625 machining scrap starts. Saw-cut bar ends, drops and crops are high-value solids. Turnings from valve, fastener and oilfield component machining are lower value per kilo but arrive in volume. B446 bar is often stamped or tagged with heat numbers, which makes bar ends easy to prove; turnings are proved by machine source and XRF.
- Keep bar ends tagged with the heat number or certificate.
- Keep N06625 bar apart from N06650 bar: N06650 carries tungsten.
- Keep 625 turnings dry, single-grade and away from 718 turnings from the next machine.
More: Inconel 625 scrap and solids vs turnings.
Related Alloy 625 Specifications
| Product form | ASTM | ASME |
|---|---|---|
| Plate, sheet and strip | B443 | SB-443 |
| Rod and bar | B446 | SB-446 |
| Seamless pipe and tube | B444 | SB-444 |
| Forgings | B564 | SB-564 |
ASTM B446 FAQ
What does ASTM B446 cover?
Hot-worked and cold-worked rod and bar in Alloy 625 (UNS N06625), UNS N06219 and UNS N06650.
What are the B446 grades for Alloy 625?
Grade 1 annealed (service up to 593°C), Grade 2 solution annealed (above 593°C, creep and rupture resistance) and Grade 3 solution annealed and cold worked (higher strength).
Is SB-446 the same as B446?
SB-446 is the ASME adoption of ASTM B446 for Boiler and Pressure Vessel Code use; bar is often certified to both.
How should B446 bar-end scrap be sold?
With heat numbers or certificates, sorted by alloy (N06625 kept apart from N06650 and N06219), and separate from turnings.
Sources and Review
Figures are quoted as published in these sources; any value we could not confirm has been left out.
- ASTM B446 Standard Specification for Nickel-Chromium-Molybdenum-Niobium Alloy, Nickel-Chromium-Molybdenum-Silicon Alloy, and Nickel-Chromium-Molybdenum-Tungsten Alloy Rod and Bar: title and scope as summarised in the AENOR catalogue listing (ASTM B446-24).
- Inconel 625 specifications as published on this site.
Reviewed by Mitesh Shah, Proprietor, Mipra Steel · Published by Mipra Steel, Khetwadi, Mumbai · Last updated