Technical note

How to read a material test certificate for wear castings

15 July 2026 6 min read

Test certificates arrive with most wear castings and are filed without being read. That is a missed opportunity, because the certificate is the only direct evidence you have about what was actually poured and how it was treated.

What a certificate should contain

Heat number, matching the marking on the casting itself
Chemical analysis. The actual measured values, not the specification range copied out
The standard and grade claimed, for example ASTM A128 Grade B-3
Hardness results with the scale and where on the casting they were taken
Heat treatment record. The cycle applied, not just the word "treated"
Dimensional conformity against the drawing revision

A certificate quoting only specification ranges rather than measured values tells you nothing about your castings. Measured figures per heat are the whole point.

Checking manganese steel against ASTM A128

For austenitic manganese steel the two figures worth checking first are carbon and manganese. Grade A calls for 1.05–1.35% carbon and 11.0–14.0% manganese. Other grades shift those ranges and may add chromium or molybdenum.

A useful sanity check is the manganese-to-carbon ratio, which should sit around 10:1. Significantly below that and the casting is more prone to carbide formation and embrittlement.

Then look at hardness. As-supplied manganese steel should be around 200–229 BHN. This is the counter-intuitive part: a manganese casting reported at 350 or 400 BHN has probably not been solution treated correctly. It will feel like a better casting and behave like a worse one, because carbides left at the grain boundaries make it brittle exactly where toughness was the reason for choosing the material.

Checking high chrome against ASTM A532

For high chrome irons, check chromium and carbon against the class and type claimed:

Common high chrome grades under ASTM A532
Class / type	Chromium	Carbon	Typical hardness
Class II Type B (15Cr-3Mo)	14–18%	2.4–3.0%	58–64 HRC
Class II Type D (20Cr-Mo)	18–23%	2.0–3.3%	58–63 HRC
Class III Type A (25Cr)	23–30%	2.0–3.3%	56–62 HRC

Molybdenum matters more than it looks. In thicker sections it is what allows the matrix to transform to martensite through the full section rather than only near the surface. A heavy casting in a low-molybdenum grade can meet its surface hardness and still be soft in the middle.

Where hardness was measured

A hardness figure without a location is close to meaningless on a heavy casting. Surface hardness is easy to achieve; through-section hardness is the difficult part and the one that determines how the part behaves once it has worn past the surface layer.

For thick sections, ask where the reading was taken. A reputable foundry will tell you, and for critical work will take readings at more than one depth.

Traceability

The heat number on the certificate should match a marking on the casting. Without that link, the certificate documents some heat, not necessarily the one that produced your part. Traceability matters most when something fails. It is what lets both sides establish whether the material or the application was at fault.

Questions worth asking your supplier

Are the chemistry figures measured for this heat, or the specification range?
Where on the casting was hardness taken, and at what depth?
Was heat treatment done in-house or subcontracted, and is the cycle recorded?
How long are inspection records retained against the heat number?
Can third-party inspection be arranged if our specification requires it?

None of these are awkward questions for a foundry that runs its own heat treatment and keeps its records. We issue chemical, hardness and dimensional results per heat and retain them against the heat number, and we are happy to walk through a certificate with you if anything on it is unclear.

Questions