A mill test certificate — MTC — is the identity document of a steel shipment. If you buy steel and cannot read one, you are trusting the seller's word for everything that matters. Here is what each section is telling you.
EN 10204 3.1 means the certificate is issued by the manufacturer's own authorised inspection representative, independent of the production department. If a "certificate" arrives with no mill letterhead, or with a trader's letterhead and no traceable heat number, it is not a 3.1 certificate.
The table lists elements as percentages by weight. Compare them against the grade limits in the standard — for 304 stainless, chromium 17.5–19.5 %, nickel 8.0–10.5 %, carbon ≤ 0.07 %. Two values deserve special attention: carbon (weldability) and sulphur plus phosphorus (cleanliness). Values near the limit are legal but worth noting if the material will be formed heavily.
Yield strength, tensile strength and elongation, measured on test pieces from the actual heat or coil. For structural grades, check that the yield meets the minimum for the thickness you bought — yield requirements drop as thickness rises, and a certificate for thin plate does not prove thick plate.
The heat (or coil) number is what links the paper to the metal. It should be stencilled, stamped or tagged on the material itself. On a multi-heat shipment, every bundle should be identifiable. If the numbers on the material do not match the certificate, stop and query before cutting anything.
It does not certify surface finish, flatness tolerance, or packaging quality — those are covered by the inspection standard (ASTM A480, EN 10051 and so on) and by the order itself. A clean MTC and a dented coil can coexist; that is why certificates and inspection are complements, not alternatives.
Send the grade, the size and the quantity — you get a costed quotation within two working days.