Indentation hardness test, performed with either 3 gf or 9 gf loads, preceded the development of microhardness testers using traditional indenters. In 1925, Smith and Sandland of the UK developed an indentation test that employed a square-based pyramidal indenter made from diamond. They chose the pyramidal shape with an angle of 136° between opposite faces in order to obtain hardness numbers that would be as close as possible to Brinell hardness numbers for the specimen. The Vickers test has a great advantage of using one hardness scale to test all materials.The first reference to the Vickers indenter with low loads was made
Leeb rebound hardness test a Brinell indentation on the same material is ~3 mm (hardness value ~400 HBW 10/3000), with a standard-compliant measuring time of ~15 seconds plus the time for measuring the indentation. 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.: 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