Selling Aluminum to Fabricators: The Material Certification Requirements That Determine the Sale

Aluminum fabricator material certification is a complexity that surprises new entrants to the market. The alloy system is broad — hundreds of registered alloys across the 1xxx through 8xxx series — but the market for premium fabricators concentrates in a relatively small number of alloys where the certification requirements are demanding and the consequences of non-conformance are severe: 2024, 6061, 7075, 7050, 2219, and a handful of others for aerospace; 6061, 6082, 5083, and 5052 for marine and structural; 5xxx and 6xxx series for automotive.

What makes aluminum certification challenging is not just the chemistry — it is the combination of alloy designation, temper designation, and product form. An aluminum plate certified as 7075-T651 is not interchangeable with 7075-T7351, even though both are 7075 alloy. The temper changes the mechanical properties dramatically: T651 (artificially aged) is stronger but more susceptible to stress corrosion cracking; T7351 (over-aged, stabilized) has lower strength but superior SCC resistance in the through-thickness direction. For a fabricator making aerospace structural brackets, using T651 where T7351 was specified is a potential safety issue, not a processing substitution.

The fabricator's incoming inspection team knows this. Their check is not just "is this 7075?" It is "is this 7075 in the correct temper with chemistry within AMS limits?"

---

The Core Aluminum MTC Requirements for Fabricators

For commercial industrial fabricators (non-aerospace), the baseline MTC requirements are governed by ASTM B-series standards:

For aerospace and defense fabricators, the governing specifications shift to AMS (Aerospace Material Specifications):

• AMS 2014 — Chemical Composition Limits for 2xxx and 7xxx Series Alloys
• AMS 4028 — 2024-T351 Plate
• AMS 4037 — 7075-T7351 Plate
• AMS 4049 — 7050-T7452 Hand Forgings
• AMS 4928 — Ti-6Al-4V Bar (for comparison — titanium bar in aerospace shops)
• AMS 2770 — Heat Treatment of Wrought Aluminum Alloys (referenced for temper qualification)
• AMS-QQ-A-250 — General Specification for Aluminum Alloy, Plate and Sheet

The key difference between ASTM and AMS specifications: AMS specifications are typically more demanding in chemistry control, traceability requirements, and mechanical property ranges. An AMS-conforming MTC must show compliance to specific AMS revision levels, and the producing mill must typically be qualified as an approved source for the specific AMS specification.

---

Temper Designation Verification: The Most Common Error

The temper designation on an aluminum MTC is not a post-processing note — it is an integral part of the material certification. The four temper series are:

Within the T-series, the number after T indicates the specific treatment sequence. T6 is artificial aging after solution heat treatment. T651 is T6 with stress relief by stretching (plate and bar). T7351 is a specific over-aging treatment that improves stress corrosion resistance at a slight cost to strength. T73 and T7351 are different: T73 is a property range, T7351 specifies both the treatment and the product form (stretched plate).

An MTC for 7075 plate that says "T651" where the fabricator ordered "T7351" is a non-conformance. The mechanical properties will be different (T651 typically has higher yield), and critically, the SCC resistance will be lower than T7351. A fabricator who misses this distinction and machines T651 plate into components that required T7351 may not discover the error until field failures occur — at which point the liability question traces back to the certificate.

---

What Aerospace Buyers Check at Incoming Inspection

Aerospace fabricators under AS9100 Rev D or NADCAP accreditation have defined incoming inspection processes for aluminum material. Their quality engineers check:

1. Alloy and temper exact match: Not approximately 7075, not "equivalent grade" — the exact alloy, exact temper, and exact product form on the MTC must match the purchase order.

2. Chemistry element by element: Every element in the AMS or ASTM composition table is checked against the certificate value. For 7075: zinc (Zn), magnesium (Mg), copper (Cu), manganese (Mn), silicon (Si), iron (Fe), chromium (Cr), titanium (Ti), other individual elements, and other elements total. All must be within AMS 2014 limits for the specific alloy.

3. Mechanical properties: Tensile strength, yield strength (0.2% offset), elongation in the specified gauge length, and (for plate thicknesses above a certain level) reduction of area. Values must be within AMS or ASTM range — not just above the minimum, but also below the maximum where both limits exist.

4. Lot or heat number matching: The lot number on the MTC must match the physical marking on the material. For aluminum plate, this is typically roll-coded on the surface. For bar, it may be an end stamp or bundle tag.

5. Mill source qualification: For AMS materials, the producing mill must be on the prime's approved manufacturer list (AML) or the customer-approved qualifier list (QAL). An aluminum bar from a mill that is not on the AML is non-conforming regardless of how good the chemistry is.

6. Certificate format: CMTR (Certified Mill Test Report) from the producing mill is required, not a distributor-issued CoC. The CMTR must be traceable to the specific production lot.

---

The Approved Source Requirement: A Distributor's Biggest Challenge

For aerospace aluminum, the approved source requirement is the most challenging aspect of the distribution business. The prime contractor (Boeing, Airbus, Lockheed, Raytheon, etc.) specifies which mills are approved to produce material for their program. This list — the AML — typically includes major aluminum producers (Novelis, Constellium, Arconic, UACJ, Aleris) and excludes smaller mills or mills without aerospace quality certifications.

A distributor who sources aluminum from a non-approved mill cannot sell it into the aerospace supply chain, regardless of the mill's quality or the material's actual chemistry. This restriction is enforced at the fabricator's incoming inspection: the MTC is reviewed, the mill is identified, the AML is checked, and material from non-approved sources is rejected.

The implications for distributors:

• Know which mills are approved for the prime contractors your fabricator customers serve
• Maintain relationships with approved-source mills and prioritize their supply for aerospace-destined stock
• When sourcing from new mills, confirm approved source status before purchase — do not assume conformance
• Be transparent with customers about the mill source; customers will check

---

Traceability Through Processing: Sawing, Slitting, and Cutting

When a distributor processes aluminum — sawing plate, cutting bar to length, slitting coil — the traceability chain must survive the processing step.

For plate: the roll-coded heat number on the plate face may be partially or fully removed by saw cuts. Each cut piece must be marked with the heat number before it leaves the saw. Methods: paint pen, scribe (for non-cosmetic surfaces), or label attachment. The processing record must document the original lot, the pieces cut, and the piece identification assigned to each cut piece.

For bar: the lot number stamp on the bar end is removed by the saw. Same marking requirement: each cut piece must be re-marked. For small-diameter bar where stamping is impractical, lot-based labeling on bags or bins is acceptable as long as individual pieces are not separated from their labeled container before use.

A distributor who cannot demonstrate that every piece leaving their facility has a traceable connection to a specific lot and MTC is exposing themselves and their customers to traceability disputes.

---

How TestCert Helps Aluminum Distributors

TestCert extracts and validates aluminum MTC fields in the same framework as steel certificates. Alloy designation, temper, all chemistry elements per the AMS or ASTM composition table, and mechanical properties are extracted and compared against the specification limits for the correct alloy and temper combination. For aerospace material, the producing mill is flagged if not on the configured approved source list.

For distributors processing aluminum — cutting plate or sawing bar — the lot tracking module maintains the link from the original incoming lot to every cut piece allocated to every customer order. Supplementary traceability records document which pieces from which lots went to which customers.

When an aerospace fabricator's incoming inspection team asks "can you confirm the mill source for lot 12345?" the answer is a query and a response in seconds — with the original mill MTC, the mill name, and the approved source status all available immediately. That response speed is the kind of service that gets a distributor onto the aerospace preferred supplier list and keeps them there.

See how aluminum distributors use TestCert to meet aerospace certification requirements — book a demo at testcert.io.