Understanding Mill Test Certificate Terms for Carbon Steel

The mill test certificate is the single document that proves a carbon steel delivery is what was ordered. Yet every week procurement teams receive certificates with terms they cannot decode – “heat number”, “batch number”, “CEV”, “PCM”, “ladle analysis”, “product analysis”, “heat treatment condition”, “TC certificate type 3.1” – and they either ignore the document entirely or accept it without reading. Both responses are dangerous. A misread certificate can let an under-strength plate enter service, let a counterfeit heat number pass acceptance, or trigger an expensive third-party dispute at port. This guide walks through every common field on an EN 10204 / ASTM A6 / JIS G0416 carbon steel certificate, explains what it means in plain language, and flags the red-flag patterns that indicate the certificate is fake, mismatched, or recycled from another heat. After reading, you should be able to read any mill certificate for hot rolled plate, section, pipe or bar with confidence.

1. MTC vs MTR vs 3.1 vs 3.2 – What is the Difference

Mill Test Certificate (MTC) and Mill Test Report (MTR) are used interchangeably and refer to the same document: a traceable record of the heat or batch. EN 10204 (the European standard adopted globally) classifies metallurgical certificates into four types:

• Type 2.1 – Declaration of compliance with the order, no test results.
• Type 2.2 – Test report based on non-specific inspection, batch-level chemistry and properties.
• Type 3.1 – Test report issued by the mill’s own inspection body, heat-number-traceable.
• Type 3.2 – Test report issued by both the mill’s inspection body and an independent third-party inspector (such as SGS, BV, Intertek, TUV, LR, DNV, ABS).

For export shipments of carbon steel plate, section, pipe, bar and forged fittings, the most common specifications are Type 3.1 and Type 3.2. Pressure vessel plates, bridge plate, ship plate and offshore applications typically require Type 3.2 with an additional class society stamp.

If a buyer asks for “3.1 certificate” and receives a Type 2.2, the goods do not meet the order. If a buyer asks for “MTC” without specifying the type, the mill has wide latitude. Specify the type in the RFQ – it is a critical part of the contract.

2. Anatomy of a Mill Test Certificate

A typical EN 10204 Type 3.1 certificate for hot rolled carbon steel plate contains the following sections:

1. Mill identification – name, address, mill location, ISO 9001 reference
2. Certificate number and issue date
3. Buyer’s order reference and our reference (heat number, coil number, plate number)
4. Product description – grade, specification, form, dimensions, quantity, weight
5. Heat number / Cast number
6. Chemical composition – ladle analysis and product analysis
7. Mechanical properties – tensile, yield, elongation
8. Charpy impact test results if ordered
9. Hardness results if ordered
10. Heat treatment condition code
11. Hydrostatic test or NDT report if applicable
12. Inspection body stamp and signature

Each field is decoded below.

3. Heat Number and Batch Number – The Backbone

The heat number (also called cast number or melt number) is the unique identifier for one batch of molten steel from a single ladle. Each plate in a heat carries the same heat number and the same underlying chemistry. The heat number is the link between the certificate and the steel in the buyer’s warehouse – it allows any later metallurgical failure to be traced back to a specific cast.

The heat number format varies by country and mill. Common examples:

• China mills – 8-digit number e.g. “23456789” or alphanumeric like “2-2345”
• ArcelorMittal – alphanumeric “M123456”
• POSCO – alphanumeric “P12345-6” (last digit identifies the cast sequence)
• JFE – alphanumeric “JFE1234A”

The batch number (also called lot number) is a finer granularity inside a heat – it identifies a specific delivery bundle, plate group, or coil within the same heat. Two plates with the same heat number but different batch numbers share chemistry but may have different mechanical tests if the mill sampled each batch independently.

Cross-check on acceptance: the heat number on each plate’s stencil, on the plate’s certificate, on the bundle strap tag and on the pre-shipment photograph should all match. Any mismatch is a red flag.

4. Chemistry Field – Ladle vs Product

The chemistry section typically reports both ladle analysis (the sample taken from the ladle before pouring) and product analysis (the sample taken from the rolled product itself). The ladle analysis is the primary certification; the product analysis confirms that no significant segregation occurred during solidification and rolling. The standards typically allow slight deviation between the two:

Element	Ladle limit	Product limit (allowable beyond ladle)
Carbon	0.20 max	+ 0.02 (for 0.20 max)
Manganese	1.20 max	+ 0.04
Phosphorus	0.030 max	+ 0.01
Sulfur	0.030 max	+ 0.01
Silicon	0.40 max	+ 0.03

If the reported product analysis is outside the allowable range, the steel does not meet the standard. The reported values are typically in 0.01 percent precision; for high-purity grades the precision may go to 0.001 percent.

5. Mechanical Test Reporting

Mechanical tests on a 3.1 certificate typically report:

• Tensile strength in MPa or ksi
• Yield strength (0.2 percent offset or 0.5 percent total elongation under load) in MPa or ksi
• Elongation in percent over a standard gauge length (50 mm, 80 mm, 200 mm)
• Charpy V-notch impact energy at a specified temperature in Joules or ft-lbf – with average of three specimens and minimum single value
• Bend test pass / fail if ordered
• Hardness results if ordered (see our hardness-testing guide)

Each result is associated with a sample location and direction (longitudinal or transverse) relative to the rolling direction. For plate, transverse samples are the default because they are the weakest orientation. For pipe, longitudinal samples are the default.

6. CEV and PCM – Weldability Indicators

CEV (Carbon Equivalent Value) is calculated from the chemistry and is the most common single number used to assess weldability of carbon steel. The IIW formula is:

CEV = C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15

Typical limits:

Application	CEV max
Mild structural (A36, S275JR)	0.45 typical
Pressure vessel (A516, P265GH)	0.43 max for thick plate
Line pipe (API 5L X65)	0.42 to 0.45 typical
Ship plate (AH36)	0.45 max typical
High-strength (A514, S690Q)	0.50 to 0.65 typical

A higher CEV means the steel is harder to weld without preheat and post-weld heat treatment. The buyer specifies the CEV maximum on the order when the welding procedure requires control of heat input.

PCM (Parameter of Cracking Measure, Ito-Bessyo formula) is an alternative weldability index more sensitive to the lower-carbon end:

PCM = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5 x B

PCM is required for some Japanese line pipe and pressure vessel specifications.

7. Heat Treatment Condition Code

The certificate must declare the heat treatment condition. Common codes for carbon steel are:

• AR – As Rolled (no heat treatment after rolling)
• N – Normalized (heated to 900 deg C and cooled in still air)
• NT – Normalized and Tempered
• Q – Quenched
• QT – Quenched and Tempered
• SR – Stress Relieved (typically 600 deg C for 1 h per inch thickness)
• TMCP – Thermo-Mechanically Controlled Process
• CR – Cold Rolled (for sheet)

For ASTM A36 plate the standard acceptance is as-rolled; A516 Gr.70 plate is normalized by default; A514 plate is quenched-and-tempered; modern line pipe X70/X80 is often TMCP. The certificate must carry the code matching the order – omitting the code or marking AR on a normalized product is a red flag.

8. Inspection Body, Stamp and Signature

On a Type 3.1 certificate, the inspection body is the mill’s own QA department. The stamp shows the mill’s ISO 17025 accreditation number, the inspector’s name and signature, and the issue date. On a Type 3.2 certificate, a second stamp from the third-party inspector is added. Both stamps should be originals (with ink seal) or be verifiable digital signatures where accepted by the contract.

9. Common Red Flags on the Certificate

Most certificate frauds are not sophisticated – they are recycled from another shipment with the heat number edited. Watch for:

1. Heat number on certificate does not match stencil on plate. Always compare.
2. Issue date earlier than order date – the certificate cannot be issued before the goods are made.
3. Chemistry values too good to be true – all elements dead-center the range, no variation within a heat.
4. Mechanical results identical for multiple plates – in practice, two plates in the same heat vary by 5 to 10 MPa.
5. Heat treatment code inconsistent with the steel grade (A514 marked AR, A516 marked QT).
6. Missing CEV when the spec demands it.
7. Charpy at the wrong temperature (e.g. -46 deg C only) but the certificate records “Charpy at 0 deg C”.
8. Third-party stamp but no third-party signature, or stamp from an agency that is not on the buyer’s approved list.
9. Font, layout or logo looks old – check the template version against the mill’s website or recent certificates.
10. Long string of delivery dates vs the certificate date – inconsistent timelines suggest the doc is rebuilt from older data.

A single red flag should trigger additional verification. Three or more red flags mean reject the certificate and ask the mill to re-issue with a fresh heat-matched test.

10. How to Verify a Certificate

Three practical verification steps:

• Online portal – most reputable mills (Tisco, Baosteel, Shougang, Ansteel, SAIL) allow buyer-direct certificate verification on their website by heat number.
• Independent chemistry check – take a third-party sample at port and run OES (Optical Emission Spectroscopy) on a 6 mm coupon. Compare to the certificate. Tolerance +/- 0.02 percent on common elements.
• Independent mechanical check – tensile and Charpy by an ISO 17025 lab. Compare to certificate. Tolerance +/- 10 MPa on tensile.

A well-run buyer’s inspection program costs roughly 0.5 to 2 percent of the order value and saves the cost of one bad heat. For high-criticality orders (boiler plate, pressure vessel, bridge plate, line pipe), the cost is mandatory.

11. EN 10204 vs ASTM vs JIS G0416 Certificates

Different regions issue certificate templates with slightly different field layouts. EN 10204 is the cleanest and most common in international trade. ASTM A6 / A20 / A370 cover similar fields but with US-specific terminology. JIS G0416 mirrors EN 10204. Chinese mills can issue any of the three with their inspection body stamp. The buyer should always specify the certificate standard, not just the steel standard.

12. How to Make the MTC Your Friend

Build these habits into your procurement routine:

1. Always state the certificate type (3.1 or 3.2) on the PO.
2. Always specify the heat treatment condition code that must be reported.
3. Always require CEV reporting if the welded application is critical.
4. Always compare certificate heat number to physical stencil on goods at receipt.
5. Always archive the certificate with the order document for at least 7 years (or per local retention rule).
6. Always verify the mill’s inspection body accreditation (ISO 17025, ISO 9001).

The certificate is the buyer’s defence against under-grade supply. It is the mill’s defence against unfair rejection claims. Treat it as a living document of the deal, not an unavoidable form.

FAQ

Is Type 3.2 always more expensive than Type 3.1?

Yes. Type 3.2 adds the third-party witnessing fee (typically 0.5 to 3 percent of the order value). For critical or high-tonnage orders, Type 3.2 is standard. For low-tonnage general service, Type 3.1 is acceptable when the mill is reputable.

Can a Chinese mill issue an EN 10204 3.1 certificate?

Yes. EN 10204 is adopted by major Chinese mills and their inspection bodies are ISO 17025 accredited. The certificate template and field set follow the EN standard, not a Chinese template.

What does “modular issue” mean on some certificates?

Modular issue means the certificate is split into separate pages – usually one page for chemistry, one for mechanical, one for traceability. The pages are linked by certificate number. Always check that all pages have the same certificate number and heat number.

What if the MTC shows Charpy but the temperature is wrong?

Reject the certificate. The Charpy temperature must be specified in the contract; if the mill tested at 0 deg C and the contract is -46 deg C, the test is invalid. Re-sample and re-test at the correct temperature, witnessed by the third party if applicable.

What is the difference between EN 10204 and DIN 50049?

DIN 50049 was the predecessor to EN 10204 and is now superseded. Certificates issued against DIN 50049 remain valid for older orders, but all new orders should reference EN 10204.

How long is the certificate valid as evidence of compliance?

As long as the goods are in service, plus the local retention period. Many buyers archive certificates for the life of the equipment. The certificate is not “expired” – the steel is what it is.

Request a Quotation

Huaxia-Steel supplies EN 10204 Type 3.1 and 3.2 mill test certificates with every carbon steel plate, section, pipe, bar and forging shipment, fully heat-number traceable, with chemistry, mechanical, Charpy, hardness and CEV reporting exactly as the buyer specifies. Send your grade, specification, certificate type and target port to [email protected] for a complete offer including the certificate sample.