The mill test certificate (MTC) is your proof of what you bought. In a market where 202 sometimes gets sold as 304, it's the single most important document in a stainless steel order — and it only helps if you know how to read it.
What a mill test certificate is
An MTC is the document, issued against the steel's heat (or cast), that records its actual chemical composition and mechanical properties and certifies it against a standard such as ASTM A240 or IS 6911. It ties a specific batch of steel to test results you can check.
EN 10204 certificate types
| Type | Name | Certified by | When you want it |
|---|---|---|---|
| 2.1 | Declaration of compliance | Manufacturer, no test results | Low-criticality / non-structural |
| 2.2 | Test report | Manufacturer, non-specific test data | General use |
| 3.1 | Inspection certificate 3.1 | Manufacturer's authorised inspector, actual heat results | The standard you should expect for genuine stainless |
| 3.2 | Inspection certificate 3.2 | Independent third party plus manufacturer | Critical or regulated work |
The fields to check on a 3.1
- Heat / cast number — ties the certificate to your specific batch.
- Grade & standard — e.g. 304 to ASTM A240 / IS 6911.
- Chemical composition — C, Cr, Ni, Mo, Mn and others, in percent.
- Mechanical properties — tensile strength, yield, elongation, hardness.
- Dimensions, manufacturer name and date.
How to use it to catch mis-grading
The chemistry exposes substitution. 304 carries 8–10.5% nickel; 316 adds 2–3% molybdenum; 202 has low nickel (~4%) propped up with high manganese. If a sheet sold as '304' shows ~4% nickel and high manganese on the certificate, it is 202 — and the MTC just saved you from a costly mistake.
Why we issue a 3.1 on every consignment
Every order from us ships with an EN 10204 3.1 mill test certificate traceable to the heat number, and we welcome third-party inspection. It's the simplest way for you to verify you got exactly the grade you paid for.
Quick answers
What is an EN 10204 3.1 certificate?
It is an inspection certificate validated by the manufacturer's authorised inspector that records the actual chemical and mechanical test results for that specific heat of steel, certified against a standard. It is the level of documentation you should expect for genuine stainless steel.
What's the difference between a 3.1 and a 3.2 certificate?
A 3.1 is certified by the manufacturer's own authorised inspector; a 3.2 adds independent third-party verification. 3.1 covers most commercial work, while 3.2 is used for critical or regulated applications.
How can a mill test certificate tell 202 from 304?
By the chemistry. 304 shows 8–10.5% nickel; 202 shows low nickel (around 4%) and high manganese. If material sold as 304 lists ~4% nickel on the certificate, it is actually 202.