A supplier reports HRC hardness for a carbide insert. Can we compare it with an HRA requirement?

Do not treat an informal HRC-to-HRA conversion as a compliant result. First confirm what was actually tested and which method the order requires. Ask for a corrected report if the scale was transcribed incorrectly, or the required testing and authorized disposition if a different test was performed.

Identify the specified scale and actual test method

Compare the order, material specification and report line by line. Identify the hardness scale, method designation and edition, specimen identity, test date and stated acceptance rule. A number without its scale is incomplete for this purpose. Also check that the certificate refers to the carbide insert rather than to the steel carrier or another component in the assembly.

Ask the issuing laboratory whether HRC is the actual measured scale or a reporting error. Do not correct the document yourself, even if the value seems familiar. The issuer should provide a traceable revision stating what changed and why. Retain the original report with the corrected version so the acceptance history remains intelligible.

The hardness-testing guide covers the general measurement topic. This case is the narrower mismatch between ordered evidence and supplied evidence, not a request to choose whichever scale produces a convenient-looking number.

Explain why a converted figure may not satisfy the contract method

ASTM's public B294-17 scope describes cemented-carbide testing on the HRA scale. That historical edition is context, not an instruction to substitute it for the method and edition governing this order. The laboratory and specification owner must identify the applicable current requirement before deciding whether the submitted result meets it.

ASTM's hardness-conversion guidance describes conversions as approximate and dependent on the material covered. A calculation therefore does not create an actual test on another scale. Do not use a steel conversion chart or an unqualified online calculator as proof that a carbide result complies with an HRA requirement.

If the contract expressly allows an alternative, identify the written allowance and its conditions. If it does not, ask the authorized technical reviewer whether a deviation can be considered. The supplier's confidence in the material does not itself change the buyer's acceptance method or the scope of the report.

Request a compliant test report rather than an informal conversion

Request a report that identifies the specimen, production lot, method, scale, results and acceptance basis. Where new testing is necessary, agree the specimen selection and disposition before consuming or altering parts. Keep any untested stock distinct from tested samples, and avoid implying that one corrected document establishes every other material requirement.

If the required test cannot be performed on the available specimen as supplied, ask the laboratory and specification owner to propose an appropriate documented route. That is a technical decision, not a reason to invent a converted result. NIST's metrology guidance is relevant background for assessing the measurement evidence and its suitability.

When discussing replacement or repeat-order inserts, retain the resolved requirement in the controlled specification. Close the discrepancy as a reporting correction, accepted deviation or completed compliant test. Those outcomes are different, and the purchasing record should not reduce all of them to “hardness accepted” without explaining which evidence supported release.