This portable method is mainly used for testing sufficiently large workpieces (mainly above 1 kg).
When using the dynamic Leeb principle, the hardness value is derived from the energy loss of a defined impact body after impacting on a metal sample, similarly to the Shore scleroscope. The Leeb quotient (vi,vr) is taken as measure of the energy loss by plastic deformation: the impact body rebounds faster from harder test samples than it does from softer ones, resulting in a greater value 1000×vr/vi.When using a magnetic impact body, the velocities can be deduced from the voltage induced by the body as it moves through the measuring coil. The quotient 1000×vr/vi is quoted in the Leeb rebound hardness unit HL.
Depending on the probe (“impact device”) and indenter (“impact body”) types that vary by geometry, size, weight, material and spring force, diverse impact devices and hardness units are distinguished, e.g.:
• Equotip impact device D with hardness unit HLD
• Equotip impact device G with hardness unit HLG
Generally, impact device types are optimized for certain application fields. This is similar to using various indenter geometries and test loads in Rockwell (e.g. HRA, HRB, HRC), Brinell and Vickers. Leeb hardness results in HL are often converted to the traditional hardness scales HRC, HB and HV mainly for convention reasons between supplier and customer.
• American standards:
ASTM A956 “Standard Test Method for Leeb Hardness Testing of Steel Products”
ASTM E140 - 12be1 "Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness"
• International standards:
ISO/DIS 16859-1 "Metallic materials - Leeb hardness test - Part 1: Test method"
ISO/DIS 16859-2 "Metallic materials - Leeb hardness test - Part 2: Verification and calibration of the testing devices"
ISO/DIS 16859-3 "Metallic materials - Leeb hardness test - Part 3: Calibration of reference test blocks"