How to Read a Mill Test Certificate (MTC)

A Mill Test Certificate (MTC), sometimes called a material test report or inspection certificate, is the document that proves a specific batch of steel meets the chemical and mechanical properties its grade claims. It is not paperwork for its own sake — it is the traceable link between the heat that was melted in our furnace and the part sitting on your factory floor.

Heat number and traceability

Every MTC starts with a heat number, unique to the melt the material came from. This number should also appear stamped or tagged on the physical material (or the bundle/pallet it ships in). If the heat number on your delivery doesn’t match the certificate in hand, stop and ask — that’s the first and most important check.

Chemical composition

A table of elements (C, Si, Mn, P, S, Cr, Ni, Mo and others depending on grade) with the actual measured percentage for that heat, verified against the standard’s specified range — not a generic range copied from a datasheet. This is what confirms the material is genuinely the grade it’s labelled as.

Mechanical properties

Yield strength, tensile strength, elongation and, where relevant, hardness — each tested on a sample from that specific batch, not a typical/nominal value. These figures are what your design calculations should actually be checked against for critical applications.

Standard reference and certification level

Look for the specification the material was tested to (ASTM A484, EN 10204, etc.) and the certificate type — a 3.1 certificate under EN 10204 means the test was witnessed and validated by an independent function within the manufacturer, which is the level we issue as standard on request.

If you ever receive material without a matching MTC, or need a certificate re-issued for your own compliance records, contact our documentation desk — every heat we produce is retained on file.