The Role and Classification of Hardness Blocks in Hardness Tester Testing

In the process of hardness testing, standard hardness blocks are indispensable. So, what is the role of hardness blocks, and how are they classified?

I.Hardness blocks mainly play three roles in hardness testing: calibrating hardness testers, enabling data comparison, and training operators.

1.During the long-term use of a hardness tester, changes may occur in the machine’s sensors or mechanical structure. Therefore, we use standard blocks marked with known hardness values to verify or adjust the accuracy of the hardness tester. Each hardness block is labeled with a hardness value; testing with the hardness block before formal detection can calibrate the indication value of the hardness tester, eliminate instrument errors, ensure that the measurement data meets standard requirements, verify the performance stability of the hardness tester, and quickly determine whether the hardness tester is in normal working condition.

2.Through the calibration of hardness blocks with unified specifications, the comparability of test results can be achieved between different hardness testers and different inspectors. By providing standard references with known hardness values, the testing standards under different hardness testers and different measurement scenarios are unified.

3.Standard hardness blocks are also commonly used in personnel training in laboratories or factories to improve operational proficiency.

Their hardness values are calibrated by authoritative institutions, featuring traceability, accuracy, and stability. The material of hardness blocks is similar to that of the workpiece to be tested (such as metal, plastic, etc.), which can match different hardness measurement methods (Brinell, Rockwell, Vickers, etc.).

II.The classification of hardness blocks is mainly based on different hardness scales, material types, and ranges of hardness values. The common types are as follows:

1. Classification by Hardness Measurement Method

This is the most commonly used classification method, corresponding to mainstream hardness tester types:

Rockwell Hardness Blocks (HRC, HRB, etc.): Compatible with Rockwell hardness testers, used for routine hardness testing of metal materials.

Brinell Hardness Blocks (HBW): Compatible with Brinell hardness testers, suitable for measuring metals with low hardness or materials with coarse grains.

Vickers Hardness Blocks (HV): Compatible with Vickers hardness testers, featuring high precision, and can measure thin workpieces, small parts, and surface-hardened layers.

Shore Hardness Blocks (HS): Compatible with Shore hardness testers, mostly used for hardness testing of large workpieces or immovable equipment.

Leeb Hardness Blocks (HL): Compatible with Leeb hardness testers, suitable for on-site and non-destructive testing scenarios.

2. Classification by Material

Metal Hardness Blocks: Including carbon steel, alloy steel, stainless steel, copper alloy, etc., covering the testing needs of most industrial metal workpieces.

Non-metal Hardness Blocks: Such as plastic, rubber, and ceramic hardness blocks, which are compatible with the hardness measurement of non-metallic materials.

3. Classification by Accuracy Grade

Standard Grade (Grade 1): Used for calibrating hardness testers, with high numerical accuracy and traceability to national metrological standards.

Working Grade (Grade 2): Used for daily testing comparison and verifying instrument stability, meeting the needs of routine production testing.

When purchasing hardness blocks, it is necessary to match the type of hardness tester, the hardness range of the workpiece to be tested, and the accuracy requirements. Calibration should follow the principles of “same standards, same conditions, and standardized operation” to ensure the accuracy and traceability of the measured values.