9
2.4 Leeb Hardness Testing Principle
It is defined as the quotient of an impact body’s rebound velocity over its impact velocity,
multiplied by 1000. Harder materials produce a higher rebound velocity than softer
materials. For a specific group of material (e.g. steel, aluminum. etc.). Leeb hardness value
represents a direct relationship to its hardness properties. For ordinary metal, conversion
curves of hardness HL versus other standard static hardness (HB, HV, HRC, etc.) are available,
enabling you to convert HL into other hardness values.
3 Preparation
3.1 Instrument Preparation and Inspection
Verification of the instrument is performed by using a standard calibrated
test block. The error and repeatability of displayed value should be within the
regulation of Appendix table 2. The instrument and impact device must be
calibrated using a standard hardness block prior to first usage or having reset
the instrument system.
Press
key, meanwhile pressing down the key to power on the
system. Then the user calibration screen shows as left below.
Test for 5 points on the standard
hardness block. It would display the
average measured value after
measuring 5 times. Press
key to change to its nominal value.
Press
key to confirm the
calibration finally. Or press the
key to cancel the calibration.
Range of adjustment:
±
30HL.
The measurement parameters, including the material setting, the
hardness scale and the impact direction can’t be changed during calibration.
3.2 Impact Device Selection
Refer to Appendix Table 1 and Table 3 for selection of impact device.
Note
：
For Verification, Take 5 tests around the test block and get your
average. This average value should be within the acceptable tolerance of the
test block value. If this value exceeds the allowable tolerance of the test block, a
calibration should be performed.