Mill test report: EN 10204 types and receiving checklist
Read a mill test report correctly, know what a 3.1 or 3.2 certificate promises, and catch a mismatched or incomplete MTR before it reaches a build.
A buyer or supplier quality engineer decides whether an incoming shipment of bar stock or plate can go into a build, and a mill test report is usually what that decision rests on. A correct read lets good material go to the line the day it arrives. A missed heat-number mismatch or an outdated specification revision puts unverified material into a build.
What is a mill test report?
A mill test report, or MTR, is the document a metal producer issues with a shipment. It records the specification, the heat or lot number, the chemical composition and the mechanical test results for that material, giving the buyer evidence that the batch meets what the purchase order or drawing calls out.
A certificate of conformance is shorter. The supplier states that the parts meet the order and may not show the measurements behind that statement. An MTR carries the actual numbers, and a certificate of conformance can point back to one to support its claim.
What do EN 10204 types 2.1, 2.2, 3.1 and 3.2 mean?
EN 10204:2004 sets four inspection document types. Types 2.1 and 2.2 are the manufacturer's own statement, with 2.2 adding test results that can come from the mill's general production instead of your specific lot. Types 3.1 and 3.2 report tests run on your delivered product, validated by an inspector independent of manufacturing, with 3.2 adding a second, outside signature. EN 10204:2004.
EN 10204 inspection document types
Matrix with four rows, one per EN 10204 inspection document type (2.1, 2.2, 3.1, 3.2), and columns for test basis, who validates the document, and typical use. Type 2.1 has no test results, just the manufacturer's statement of compliance, with no independent validation. Type 2.2 has non-specific test results, which can come from the mill's general production rather than the delivered lot, issued by the manufacturer with no independent validation. Type 3.1 has specific test results from the delivered product itself, validated by the manufacturer's authorized inspection representative who is independent of manufacturing. Type 3.2 has the same specific test results, validated by both that representative and a second party, either the purchaser's authorized representative or an official inspector.
| Type | Test basis | Who validates | Typical use |
|---|---|---|---|
| 2.1 | No test results, just a statement of compliance with the order | Manufacturer (no independent validation) | Low-risk commodity material where a specification match on paper is enough |
| 2.2 | Non-specific test results, which can come from the manufacturer's general production and not necessarily the delivered lot | Manufacturer (no independent validation) | Material where some test evidence helps, but lot-specific testing isn't required |
| 3.1 | Specific test results from the delivered product itself | Manufacturer's authorized inspection representative, independent of manufacturing | Aerospace, defense and pressure-equipment orders that call out a 3.1 report |
| 3.2 | Specific test results from the delivered product itself | Manufacturer's authorized inspection representative, plus the purchaser's authorized representative or an official inspector | Orders or rules that require the purchaser's or an official inspector's witness, such as pressure-equipment material from a mill without a certified materials QA system |
Only types 3.1 and 3.2 report tests run on the delivered lot itself, and only 3.2 adds a second, independent signature.
A purchase order or drawing calls out the type you need. Flag a 2.2 report against an order that called for 3.1 or 3.2 as a nonconformance at receiving. The tests behind a 2.2 report may have run on a different heat.
Selling into the EU?
Under the Pressure Equipment Directive, the equipment manufacturer shall obtain the material manufacturer's documentation for every material. For the main pressure-bearing parts of category II, III and IV equipment, that documentation shall take the form of a certificate of specific product control, which in practice means an EN 10204 3.1 or 3.2 report with results from the delivered material. Directive 2014/68/EU, Annex I, point 4.3. Where the material manufacturer's quality system has been certified by an EU competent body after a specific assessment for materials, its certificates are presumed to meet this point. In Germany, material manufacturers usually get that assessment under AD 2000-Merkblatt W 0, an industry code rather than law, and then issue EN 10204 3.1 certificates. A 3.2 report, with an inspector's second signature, is typically needed only where the mill lacks that certification. AD 2000-Merkblatt W 0 (edition 2023-08).
When does a test report need validating, not just checking?
Whenever you use a supplier's test report to accept material, AS9100 8.4.2 expects a process to check the reported values against the requirements. Where your customer or your team has identified raw material as a significant operational risk, such as a critical item, AS9100 8.4.2 goes further and requires a process to validate the accuracy of the reports themselves.
Checking every value against the specification's limits is the baseline. Validating accuracy usually means sending samples from incoming lots to an independent lab on a set schedule, weighted toward the riskiest material and supplier pairs, and comparing the lab's results with the mill's numbers. Cite the requirement by its AS9100 clause and recheck the reference when IA9100 replaces AS9100D.
In the United States
DFARS 252.225-7009 requires that specialty metals in an item delivered under a covered DoD contract be melted or produced in the United States, its outlying areas, or a qualifying country, and the requirement flows down through subcontracts. DFARS 252.225-7009(b) and (e). The clause doesn't name the mill test report as required evidence, but the melt line on that report is the usual proof. Before you accept specialty-metal stock against a covered contract, confirm the report names the country where the heat was melted, or for powder-derived metal where it was atomized, sputtered or consolidated, and that the country is the United States, a US outlying area or a qualifying country. A rolling or forging country doesn't count. DFARS specialty metals covers the qualifying-country list and the exceptions.
How do you read and check a mill test report?
Match the heat or lot number on the report to the number stamped, tagged or painted on the physical material. Then confirm the specification and revision match the purchase order, and check that every reported chemistry and mechanical value falls inside that revision's limits.
The figure below walks through each field on a typical report, using plainly illustrative numbers, not the limits of any real specification.
Reading a mill test report
Annotated table of the seven fields on a typical mill test report, each with a plainly illustrative example value, what to check that field against, and the most common defect found in that field. The fields are the heat or lot number, chemical composition, mechanical properties, specification and revision, heat treatment condition, the melt and country of origin line, and the certifying statement with signature.
| Field | Illustrative example value | What to check | Common defect |
|---|---|---|---|
| Heat or lot number | Heat 4A19K2 | Matches the number stamped, tagged or painted on the physical material | Heat number on the tag doesn't match the report, or is missing |
| Chemical composition | C 0.05%, Mn 1.10%, Cr 17.50% | Every reported element falls inside the limits of Specification X, Revision C | One or more elements outside the specification's range, or limits printed for the wrong grade |
| Mechanical properties | Yield 240 MPa, tensile 570 MPa, elongation 40% | Meets Specification X's and the purchase order's minimums, including impact or toughness values if required | A rounded or marginal value with no test method named, or a required property left off the report |
| Specification and revision | Specification X, Revision C | Matches the revision named on the purchase order and drawing, since limits can change between revisions | An older or newer revision than the purchase order specifies, unnoticed |
| Heat treatment condition | Solution annealed | Matches the condition the specification and drawing call for | Condition stated generically instead of the actual process and temperature |
| Melt and country of origin line | Melted in Country X; rolled in Country Y | The melt country matches the country your contract or a flowed-down clause requires | Melt line left blank, or only a rolling or shipping country given |
| Certifying statement and signature | "This is to certify..." with a named signer and title | Shows a name and title, and for a 3.1 or 3.2 report, identifies the authorized inspection representative | Unsigned report, a generic stamp with no name, or a signature block that doesn't match the mill's usual format |
Most mill test reports carry the same handful of fields; the specification revision and the melt line are easy to miss at receiving.
Check the specification revision as carefully as the numbers on the report. A report citing an older revision can carry different chemistry or mechanical limits than the revision named on this purchase order, and a number that passes the old revision can fail the new one.
A report with no signature, a stamp instead of a name and title, rounded values with no test method named, or a heat number that doesn't match the tag on the material is worth a second look before it moves past receiving inspection. Hold the lot, ask the supplier for the correct report, and if the paperwork can't be fixed, test the material itself before you accept it.
What about certificates issued by a distributor?
A distributor buys metal from a mill and doesn't melt it. EN 10204 expects a distributor to pass on the mill's original inspection document, or a copy, without changing it, identified so it can be traced to the material you received. EN 10204:2004. Aerospace distributors certified to AS9120B work under their own traceability requirements as well.
A distributor certificate with no mill report attached, or one that names a heat number nothing else on the shipment matches, is a common way a build ends up waiting on paperwork that should have arrived with the material. Your team can open each request as a task and hand it to Scout Agent, who follows up with the supplier by email and phone.
Why can't chemistry alone prove where the metal was melted?
Chemical composition tells you the alloy, not the country where it was melted. A mill in one country and a mill in another can each produce material that passes the same specification with nearly identical chemistry, so a lab report on the metal can't confirm or contradict a claimed melt location.
Melt and country of origin depend on the mill's own paper trail, and no receiving test can stand in for it. Treat a country claim with no supporting paper trail as a gap to close at receiving, before the material goes into a build.
What belongs on the purchase order?
Name the exact specification and revision on the order, since limits can change between revisions and the material grade alone doesn't fix them. State the inspection document type you require, such as an EN 10204 3.1 or 3.2, instead of leaving the type up to the mill or distributor.
If a contract or customer requirement sets a country-of-melt or country-of-production rule, put that requirement on the order too, so a supplier confirms it before shipping rather than after you reject the lot at receiving. An order that names only a grade leaves the mill free to ship whatever inspection document it normally issues for that grade, which may be less than your quality system or your customer's contract requires. Carrying that evidence forward into your own raw-material traceability record is easier when the requirement was on the order from the start.
Questions teams ask
Can a 2.2 report substitute for a 3.1 when a drawing calls out 3.1?
No. A 2.2 report's test results can come from the mill's general production instead of your heat, so it doesn't meet a 3.1 or 3.2 requirement. Get a 3.1 report backed by tests on your heat, reject the shipment, or take it to your material review board for a deviation your customer approves.
Does a mill test report expire?
EN 10204 sets no expiry date, but specifications get revised. A report citing an old revision against a purchase order calling a newer one is a mismatch to resolve, the same as a wrong grade would be.
Who signs an EN 10204 3.2 certificate?
The manufacturer's authorized inspection representative, who is independent of manufacturing, signs it, and so does either the purchaser's authorized representative or an inspector designated by the official regulations, depending on what your contract requires. EN 10204:2004.
Can a supplier issue its own certificate instead of forwarding the mill's report?
No, not when your purchase order or quality system calls for the mill's report. A supplier's own certificate doesn't replace it; it's a certificate of conformance, which a mill test report can support.
If your team keeps chasing missing or mismatched mill reports from mills and distributors, talk to our team about handing that follow-up to Scout Agent.
This article is general information, not legal or tax advice. Check how the rules apply to your business with your legal or tax advisor.
Sources (6)
- EN 10204:2004, Metallic products — Types of inspection documents (DIN EN 10204:2005-01)
- AS9100D, Quality Management Systems — Requirements for Aviation, Space, and Defense Organizations
- AS9120B, Quality Management Systems — Requirements for Aviation, Space, and Defense Distributors
- DFARS 252.225-7009, Restriction on Acquisition of Certain Articles Containing Specialty Metals
- Directive 2014/68/EU of the European Parliament and of the Council on the harmonisation of the laws of the Member States relating to the making available on the market of pressure equipment
- AD 2000-Merkblatt W 0 (edition 2023-08), Materials for pressure vessels — General principles for materials