POLDI hardness tester, as well as Brinell hardness tester, may be used for all forgeable iron and steel types with the exception of austenitic steels, e. g. steel with 25 % Ni, steel with 14 % Mn, corrosion-resistant Cr Ni steel, non-magnetic steel, etc. Each calibrated steel piece can be used for about 40 tests Load is applied by a hammer blow on the specimen and a standard test bar in linear direction through ahardened steel ball of 10 mm dia. The impact load on both is the same. The extent of indentation on thespecimen and the test bar depends on their hardness. The two diameters of indentations on test bar andspecimen are measured by a magnifier supplied along with the tester. The hardness of the specimen can bedetermined, by referring got the chart supplied with the machine.