AMS and ASTM Nickel Alloy Cross Reference: 625, 718 and Hastelloy X

A drawing that quotes AMS 5596, a purchase order that says ASTM B443, and a mill certificate stamped ASME SB-443 can all describe the same sheet of Inconel 625. The table below puts the common AMS and ASTM designations side by side so you can confirm which document governs the grade, which governs the form, and which one you actually need to receive with the material.

 

Two rules explain most of the confusion. First, AMS numbers are aerospace material specifications and are split by product form: a plate specification will not accept a bar, and a bar specification will not accept a plate.

 

Second, ASTM B-numbers and ASME SB-numbers are the same document published by two bodies, so B443 and SB-443 are not alternatives to each other, they are the same specification under two covers.

The rest of this page takes each designation in turn and states what it covers, what it does not cover, and the number a buyer should put on the order.

ASME SB-443 / ASTM B443: Inconel 625 Plate and Sheet

This is the specification most 625 sheet and plate is bought against. It covers plate, sheet and strip in UNS N06625, and it is the document your mill certificate should cite if you order 625 plate. The annealed minimums are 415 MPa yield and 827 MPa tensile. SB-443 is the ASME printing of the same ASTM B443 text, so either citation is acceptable on a certificate. Related stock: ASME SB-443 Inconel 625 plate.

AMS 5599: 625 Sheet, Strip and Plate for Aerospace

AMS 5599 is the aerospace counterpart of B443 and is the number that appears on drawings for aircraft ducting, engine seals and exhaust components. It adds aerospace traceability and heat-lot control on top of B443, but it is a plate and sheet specification only. A purchase order that quotes AMS 5599 for bar will be rejected by a mill, because bar is covered by AMS 5666 instead. Related stock: Inconel 625 plate and 625 sheet.

AMS 5666: 625 Bar, Forgings and Rings

AMS 5666 covers 625 in bar, forging and ring form. It is the number to quote when the part is machined from solid stock rather than formed from sheet, and its ASTM counterpart is B446, not B443. This is the single most common source of confusion on 625 orders: the drawing says 625, the buyer quotes the plate standard, and the mill has to reject the order because the product form does not match the specification.

AMS 5596: 718 Sheet, Strip and Plate

AMS 5596 covers Inconel 718 sheet, strip and plate in UNS N07718, and its ASTM counterpart is B670. 718 is age hardenable, so the specification states properties after the ageing treatment rather than in the annealed condition. A plate certificate quoting AMS 5596 without stating the ageing condition is incomplete: the same sheet reaches very different strength levels depending on whether it is solution treated or fully aged. Related stock: Inconel 718 plate.

AMS 5662: 718 Bar and Forgings, Solution Treated

AMS 5662 covers 718 bar and forgings supplied in the solution treated condition, ready for the purchaser to age after machining. It is the number to quote when you want to machine first and heat treat afterwards, which is normal for complex parts where distortion during ageing has to be corrected by finishing. Its ASTM counterpart is B637.

AMS 5663: 718 Bar, Forgings and Rings, Aged

AMS 5663 covers the same product forms as AMS 5662 but supplied already aged, with a minimum 0.2 percent yield strength of 1034 MPa and a minimum tensile of 1241 MPa. This is the number that appears on finished fastener and landing gear stock. The practical distinction for a buyer is simple: 5662 means you age it, 5663 means the mill aged it and the certificate proves it.

AMS 5536: Hastelloy X Sheet, Strip and Plate

AMS 5536 covers Hastelloy X, UNS N06002, in sheet, strip and plate form, with ASTM B435 as its counterpart. Hastelloy X is a nickel-chromium-iron-molybdenum alloy built for high temperature oxidation resistance rather than aqueous corrosion, so it belongs on combustion and heat-treat fixture work, not on chemical process equipment where C276 would be chosen. It is not a 625 substitute, despite both being nickel alloys with similar-looking designations. Related stock: Hastelloy X plate.

AMS 5643: 316 Stainless Bar

AMS 5643 covers 316 stainless bar in UNS S31600, with ASTM A479 as the comparable specification. It sits in this table because it is frequently quoted alongside the nickel alloys on the same drawing package, and because buyers sometimes assume an AMS number implies a nickel alloy. It does not: 5643 is a stainless grade, and its corrosion limits are a different order of magnitude from 625 or C276. Related stock: 316L stainless plate.

How to Read a Cross Reference Without Getting Burned

Four checks settle almost every specification mismatch before the material ships:

• Match the product form first. A plate standard never covers bar, and the AMS series splits them deliberately.
• Treat B-numbers and SB-numbers as the same document. B443 and SB-443 are ASTM and ASME printings of one text, not two grades.
• Check whether the alloy is age hardenable. For 718, the certificate must state the heat treatment condition, or the strength figures mean nothing.
• Confirm the UNS number, not just the trade name. 625 is N06625 and Hastelloy X is N06002; the trade names are marketing labels and the UNS number is what the mill verifies.

If you have a drawing that quotes a specification you are not sure about, send it over with the required form and quantity and we will tell you which standard governs it and which stock item matches. The plate side of the range is listed under Inconel plate and Hastelloy plate.

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