“Aerospace grade” gets used a lot — in marketing copy, supplier catalogs, and casual conversation in machine shops. But aerospace-grade metal isn’t a vague term. It has a specific, documented, verifiable meaning. If you’re sourcing metals for aerospace applications, here’s exactly what you need to know.
## It Starts with the Specification
Aerospace-grade metals are defined by their compliance with a published material specification. The most common specification bodies in U.S. aerospace are:
### AMS — Aerospace Material Specifications
Published by SAE International, AMS specs define the chemistry, mechanical properties, heat treatment, testing requirements, and documentation standards for a specific alloy and condition. Examples:
– AMS 4928 / AMS 6931 — Titanium Ti-6Al-4V bar ([view product](https://www.flightmetals.com/products/titanium/ams-6931-titanium-6al-4v-annealed-bar/))
– AMS 4911 — Titanium Ti-6Al-4V sheet and plate ([view product](https://www.flightmetals.com/products/titanium/ams-4911-titanium-6al-4v-sheet-plate/))
– AMS 5662/5663 — Inconel 718 bar ([view product](https://www.flightmetals.com/products/nickel/nickel-718-aged-bar-per-ams-5663/))
– AMS 4045 — Aluminum 7075-T6 sheet and plate
– AMS 5643 — 17-4 PH stainless steel bar
### ASTM
American Society for Testing and Materials specs are widely used in aerospace, particularly for structural aluminum and stainless steel. ASTM specs often overlap with AMS; an aerospace drawing may call for either or both.
### MIL-SPEC
Military specifications (MIL-DTL, MIL-A, etc.) are still referenced in defense aerospace and some commercial programs, though many have been superseded by AMS.
### Customer-Specific Specs
Boeing, Airbus, Lockheed, Northrop, and other primes issue their own material specifications (e.g., BMS — Boeing Material Specifications) that often supplement or supersede AMS requirements for their programs.
## The Certified Material Test Report (CMTR)
The CMTR — sometimes called a mill cert, cert, or MTR — is the document that traces a piece of metal to its original heat or lot of production. A legitimate aerospace CMTR will include:
– Mill name and location
– Heat or lot number
– Material specification and revision
– Chemical composition (heat analysis and product analysis)
– Mechanical test results (tensile, yield, elongation, hardness)
– Certification statement from an authorized signatory
Without a traceable CMTR, the metal cannot be used in a certified aerospace application — regardless of how well it otherwise meets requirements.
> At Flight Metals, every order ships with a CMTR traceable to the original mill heat. We never substitute or back-certify material. If we can’t provide full traceability, we won’t make the sale.
## What AS9100 Means for Your Supplier
AS9100 is the quality management system standard for the aviation, space, and defense industry. It builds on ISO 9001 and adds aerospace-specific requirements for configuration management, risk management, FOD prevention, and counterfeit parts prevention.
When your metals distributor is AS9100-certified, it means:
– Their purchasing, receiving inspection, and storage processes meet aerospace QMS standards
– Their personnel are trained on AS9100 requirements
– Their supplier base is evaluated and approved
– They are audited regularly by a third-party registrar
Flight Metals is AS9100-certified. You can learn more about our quality commitment on our [About page](https://www.flightmetals.com/about-new/).
## Red Flags That a Metal May Not Be Aerospace Grade
Counterfeit and non-conforming material is a real problem in aerospace supply chains. Watch for:
– No CMTR, or a CMTR that doesn’t trace to a recognized primary mill
– “Re-certified” or “back-certified” material (a distributor re-issuing certs they didn’t originate)
– Missing heat or lot numbers
– Price that seems too good to be true for a specialty alloy
– No AMS specification listed on the CMTR
– Supplier with no quality certifications (ISO, AS9100)
> The aerospace industry maintains databases of suspect counterfeit parts (GIDEP, CASR). Knowingly introducing non-conforming material into an aerospace supply chain carries serious legal and safety consequences.
## Frequently Asked Questions
**What is a CMTR?**
A Certified Material Test Report (CMTR) is a document issued by the producing mill that certifies a specific heat or lot of metal meets the requirements of the applicable material specification. It includes chemistry and mechanical test data, and must be traceable to the original melt.
**Is AS9100 required to buy aerospace metal?**
AS9100 is not required to purchase aerospace metal, but it is often required by prime contractors and Tier 1 manufacturers for their approved supplier lists. Buying from an AS9100-certified distributor means the material has passed through a documented quality system.
**What’s the difference between AMS and ASTM?**
Both are published material specifications, but AMS (Aerospace Material Specifications) are written specifically for aerospace applications and typically carry tighter chemistry, testing, and documentation requirements than ASTM equivalents.
## How Flight Metals Ensures Aerospace Compliance
Flight Metals is AS9100-certified and sources exclusively from primary mills and approved domestic distributors. Our receiving inspection process verifies incoming CMTRs, and our order management system maintains full traceability from your purchase order to the original mill heat.
If you’re unsure whether a material source meets your program’s requirements, contact our team. We’ll help you evaluate traceability documentation and confirm compliance.
[View our products](https://www.flightmetals.com/products/) | [Request a quote](https://www.flightmetals.com/quote/) | [Contact us](https://www.flightmetals.com/contact-us/)Related reading: [What Metals Do Aerospace Companies Actually Use?](https://www.flightmetals.com/what-metals-do-aerospace-companies-use/) | [What’s the Difference Between Aerospace and Regular Metal?](https://www.flightmetals.com/difference-between-aerospace-and-regular-metal/)
