How to Read a Casting Material Test Report (MTR) — Ultimate Cheat Sheet
A Material Test Report (MTR) — also called a Mill Test Report or Works Certificate — is your primary quality assurance document when sourcing castings from China. This guide teaches you exactly what to check, what the numbers mean, and how to spot problems.
Anatomy of a Casting MTR
A standard casting MTR contains these sections:
Header Information
| Field | What It Tells You | Red Flag |
|---|---|---|
| Foundry name & address | Who made it | Vague or missing |
| Order/contract number | Which order this batch belongs to | Missing — can't match to your PO |
| Part number & description | Which part in your order | Mismatch with your part |
| Heat/lot number | Unique identifier for traceability | No heat number |
| Cast date | When it was poured | Date mismatch with delivery |
| Quantity | Parts per heat | Quantity less than ordered |
| Specification | Standard the material must meet (e.g., ASTM A216 WCB) | No specification listed |
Chemical Composition
Measured by Optical Emission Spectroscopy (OES). Every element is listed as actual value vs. specification limit.
For GB/T 1591 Q355 steel, a typical MTR shows:
| Element | Spec Min | Spec Max | Actual Value | Pass? |
|---|---|---|---|---|
| C | — | 0.20 | 0.17 | ✓ |
| Si | — | 0.55 | 0.38 | ✓ |
| Mn | 0.90 | 1.60 | 1.32 | ✓ |
| P | — | 0.035 | 0.018 | ✓ |
| S | — | 0.035 | 0.012 | ✓ |
| CEV | — | 0.44 | 0.39 | ✓ |
Key things to verify: (1) All actual values are within spec limits, (2) Carbon equivalent (CEV) is acceptable for welding, (3) Phosphorus and sulfur are low (high P/S affects toughness), (4) The actual values are reasonable for the specified grade — if actual C is 0.17% and spec is 0.20% max, it's correct for WCB.
Mechanical Properties (Tensile Test)
Tested on a separately cast test bar (per the casting specification). Must meet minimum values:
| Property | What It Measures | Typical Spec (WCB) |
|---|---|---|
| Tensile Strength (UTS) | Maximum stress before breaking | ≥ 485 MPa |
| Yield Strength (YS) | Stress at permanent deformation | ≥ 250 MPa |
| Elongation (EL%) | Ductility — how much it stretches | ≥ 22% |
| Reduction of Area (RA%) | Ductility in cross-section | ≥ 35% |
Hardness Test
Measured in Brinell (HB) or Rockwell (HRC). Most castings specify a Brinell range, e.g., "143–187 HB" for ASTM A216 WCB.
Common Specs You'll See from Chinese Foundries
| Spec | Material | Tensile Min | Yield Min | El Min |
|---|---|---|---|---|
| GB/T 11352 HT250 | Grey iron | 250 MPa | — | — |
| GB/T 14408 QT500-7 | Ductile iron | 500 MPa | 320 MPa | 7% |
| GB/T 2100 ZG15Cr13 | Martensitic SS | 620 MPa | 450 MPa | 16% |
| ASTM A216 WCB | Carbon steel | 485 MPa | 250 MPa | 22% |
| ASTM A351 CF8 | Austenitic SS | 485 MPa | 205 MPa | 35% |
| ASTM A351 CF8M | Austenitic SS | 485 MPa | 205 MPa | 35% |
What to Check Every Time
- ☐ Heat number on MTR matches the heat number stamped/marked on the casting
- ☐ All actual chemistry values are within spec limits
- ☐ All mechanical properties meet minimum requirements
- ☐ Specification matches what you ordered (don't accept HT250 when you specified WCB)
- ☐ Heat treatment condition matches (annealed, normalized, quenched & tempered, etc.)
- ☐ Test bar location is specified (top, side, or separate cast per standard)
- ☐ Certificate is signed/dated and not expired (some specs require retest after 12–24 months)
Traceability: The Heat Number is Your Key
The heat number connects your physical casting to the MTR. Every casting in a shipment should be stamped or tagged with the heat number. This means:
- If one part fails in service, you can trace back to the entire heat/lot
- If a defect is found, the foundry can investigate the melt records
- Quality claims are validated by matching heat numbers
Frequently Asked Questions
What is a Material Test Report (MTR)?
An MTR documents the chemical composition and mechanical properties of a specific batch of metal, certifying the material meets the specified grade and is traceable to a heat/lot number.
What is a heat number?
A heat number is a unique identifier for each batch of molten metal. Every casting from that melt carries the heat number, enabling full traceability back to raw materials, melting conditions, and test results.
What is CEV (Carbon Equivalent Value)?
CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15. It predicts weldability. CEV <0.40 is good; CEV >0.50 may require preheat. Most foundry MTRs include it.
Can I use a casting with MTR values above the spec minimum?
Yes, as long as it's within the specification range — and it's actually better (higher strength). What you can't accept is values outside the range (below minimum for mechanical properties, above maximum for chemistry).
Need Help Verifying Casting MTRs?
We review MTRs as part of our quality control service. Upload your MTR and we'll verify compliance, flag any issues, and advise on acceptance within 24 hours.
Get MTR Review →