Leeb vs UCI hardness testing: method and scale

Start with the measured response

Leeb and ultrasonic contact impedance (UCI) use different physical measurements. The two brief descriptions below help you recognize the method discussed in a lesson.

Sources: Proceq: the Leeb principle; Proceq: UCI measurement principle.

Separate the method from the displayed scale

For one concrete example, Proceq’s Leeb D specifications list HLD separately from conversion scales that include HV and HRC. A displayed scale can therefore differ from the instrument’s native measurement scale.

ASTM A1038’s public scope describes UCI as comparative hardness testing with results reported on common hardness scales. A familiar scale label alone does not identify the physical method used.

ASTM E140 explains that hardness conversions are approximate and depend on the material. Keep the conversion basis visible in your study notes; a converted value is not automatically interchangeable with a result obtained by another test.

Sources: Proceq Leeb D: native and conversion scales; ASTM A1038-26: public UCI scope; ASTM E140: public conversion guidance.

Try two fictional study captions

Imagine a lesson supplies these two captions without readings or equipment details. Write down what each tells you, then underline what is still unknown.

• Card A: “Leeb device; converted HV displayed.”
• Card B: “UCI probe; HV displayed.”

Check your explanation and plan your training

Both captions identify a displayed scale, but they name different methods. Neither supplies the exact device or probe, material, applicable conversion information or governing requirement. A shared label alone does not establish equivalent testing or component acceptability. This exercise helps you read a lesson; it is not an operating procedure.

Try explaining each method in your own words, then label method and scale separately in your next study example. Continue with test variables, conversion limitations and reporting.

NDT Academy’s Hardness Testing course covers Brinell, Rockwell, Vickers, Knoop and portable Leeb/UCI methods. Compare the syllabus with your employer’s equipment and training plan. Formal instruction and course assessment do not replace equipment-specific practice or award personnel certification.