Hardness of Metallic Instruments
A new ASTM International standard describes a hardness test method based on measurement of indentation depth into test material. The instruments covered in the new standard, developed by ASTM’s committee on mechanical testing (E28), are used by the oil and gas, transportation, and machinery and tooling industries.
These instruments referenced in the standard, which will soon be published as E3246, are generally portable and cover an application range not served by instruments standardized in other test methods.
According to ASTM International member Tom Ott, the main advantage of the new standard is that the technique described allows indentation depth hardness testing when there is only access to one side of the test material. Additionally, the capability for the tool to be implemented in a portable device can be brought to a part that is too large or heavy to be tested by other conventional indentation hardness testers.
“Until now, most portable hardness test materials either required access to both sides of the part to be tested, or determined the hardness based on a measurement other than indentation depth,” says Ott. “Determining hardness by indentation depth is perhaps the most robust way to determine hardness because the user is directly measuring an amount of the plastic deformation of material under test.”
Ott notes that the new standard will help reduce waste by providing the ability to test items and maintain quality control without wastefully destroying them to test and confirm quality.
Ott says that the mechanical testing committee is looking for laboratories and organizations that use instruments conforming to this standard to participate in a round-robin study to expand the precision and bias statement now present in the standard. All interested parties are welcome to join the committee.
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