We carry out Hardness Testing in field with the morden portibal equipments based on principal of LEEB's HARDNESS TESTING METHOD.
Short discription of this method is as below :
IN SITU HARDNESS TESTING
Technically, this principle of measurement is implemented by means of an impact body which has a spherical tungsten carbide tip and which is impelled onto the test surface by spring force. The speeds after and before the impact are each measured in a non-contact mode. This is done by a small permanent magnet within the impact body which generates an induction voltage during its passage through a coil. With this voltage being proportional to the speed. The Leeb hardness value, HL, is calculated from the ratio of the impact and rebound speed.
Conversion tables stored in the instrument allow to measure the hardness in standard scales (HV, HB, HS, HRC, HRB, N/mm2) and displayed in desired scale on the screen of the equipment. These modern rebound hardness testing equipment, therefore, offer a fast, reliable and economical alternative to conventional bench-top hardness testers.
Hardness testers using Leeb's method operate in a slightly different manner as compared to standard testing methods like Vickers, Rockwell or Brinell. The hardness is indirectly measured via the loss of energy of a so-called impact body. A mass is accelerated to the surface of the test object and impinges on it at a defined speed, i.e. kinetic energy. The impact creates a plastic deformation of the surface, i.e. an indentation, due to which the impact body loses part of its original speed or energy. It will lose more speed by creating a bigger indentation and, thus, at softer material.