What ASTM B443 Covers
B443 is the flat-product specification for Alloy 625. It covers rolled plate, sheet and strip in two alloys:
- UNS N06625, nickel-chromium-molybdenum-niobium (columbium) alloy, better known as Alloy 625 or Inconel 625.
- UNS N06219, nickel-chromium-molybdenum-silicon alloy, supplied in the solution annealed condition only.
The specification sets requirements for chemical composition, tensile and yield strength, elongation, and dimensions and tolerances (thickness, width, length, flatness, edges and so on), and says how material is sampled and tested to show it conforms.
This is our own summary of the scope, not the standard itself. The current edition from ASTM sets the full requirements.
B443 Grade 1 and Grade 2 for Alloy 625
Alloy 625 under B443 is furnished in two heat-treated conditions, and the grade tells you what service the material was bought for.
| Grade | Condition | Intended service |
|---|---|---|
| Grade 1 | Annealed | Normally used at service temperatures up to 593°C (1100°F) |
| Grade 2 | Solution annealed | Used above 593°C where resistance to creep and rupture is needed |
The scope also warns that hot working or re-annealing can change the properties significantly. For scrap that warning does not matter: Grade 1 and Grade 2 offcuts are the same chemistry and are melted the same way. The grade marking is still useful because it confirms the material is N06625.
ASTM B443 and ASME SB-443
ASME adopts ASTM material specifications for use under the Boiler and Pressure Vessel Code and prints them in Section II, Part B with an "SB" prefix. Plate certified to SB-443 is therefore made to the same requirements as B443, and pressure-vessel material is often dual-certified and dual-marked. See ASME SB and SA specifications for how the two systems relate.
Alloy 625 Composition in Brief
For the full composition, identification checks and the other product specifications, see the Inconel 625 scrap page. The nominal analysis used across this site is about 62% nickel, 21.5% chromium, 9% molybdenum, 3.6% niobium and up to 5% iron (shown there as 4% nominal). B443 itself sets the limits for each element; we do not reproduce its table here.
| 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 |
| Butt-weld fittings | B366 | SB-366 |
What B443 Means When You Sell or Buy Scrap
Plate and sheet are among the most valuable forms of Alloy 625 scrap: plate-cutting skeletons from flame or waterjet cutting, sheet trim from bellows and expansion-joint makers, and strip ends from welded-tube mills. A B443 or SB-443 marking with a heat number is strong evidence of grade, and buyers will usually accept a lot faster when the marking is visible in the photos.
- Photograph the stencil or ink marking showing B443/SB-443, N06625 and the heat number.
- Keep any mill certificate (EN 10204 3.1); see how to read one.
- Keep N06219 offcuts apart: it is a different alloy with silicon instead of niobium.
- Keep plate skeletons clean of slag, paint and protective film where possible.
Ready to sell? Offer a lot or read the guide to selling Inconel scrap.
ASTM B443 FAQ
What does ASTM B443 cover?
Rolled plate, sheet and strip in Alloy 625 (UNS N06625) and in UNS N06219, with requirements for chemistry, mechanical properties, dimensions and testing.
What is the difference between B443 Grade 1 and Grade 2?
Grade 1 is annealed and normally used at service temperatures up to 593°C (1100°F). Grade 2 is solution annealed and used above 593°C where creep and rupture resistance is needed.
Is ASME SB-443 the same as ASTM B443?
ASME adopts ASTM B443 as SB-443 for pressure equipment under the Boiler and Pressure Vessel Code. Material is commonly certified to both.
Does the B443 grade affect the scrap value of 625 plate?
Not in practice. Grade 1 and Grade 2 offcuts have the same chemistry. The marking is valuable because it proves the material is N06625.
Sources and Review
Figures are quoted as published in these sources; any value we could not confirm has been left out.
- ASTM International, B443 Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625) and Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219) Plate, Sheet, and Strip: title, abstract and scope as listed in the ASTM store.
- Inconel 625 nominal composition and related specifications as published on this site.
Reviewed by Mitesh Shah, Proprietor, Mipra Steel · Published by Mipra Steel, Khetwadi, Mumbai · Last updated