Tempering (odpuszczanie) - heat treatment that is used for previously hardened steal. The target is to remove hardening stresses and the change of physical properties of hardened Steel (most of all the increase the impact resistance of Steel The treatment is based on heating until 1509 to 650°C keeping in this temperaturę and than cooling. As the result of this treatment the martensite that is the stmcture of hardened Steel is disintegrated for a very smali grains