The aim of the study was to determine the effect of the circles of damping by using two types of oils ((ASTRALUBE and SHIELD)) as well as the use of central damping of a third oil resulting from the mixing of these two oils on the hardness and tensile strength of the two types of minerals have been chosen and two iron Carbon type (CK 45) and on alloy type (40 X) , where the operation took place by damping these metals to those medias oily three after he was placed in a furnace
dedicated to raise the temperature of each of them to ( 850 ) degrees Celsius and the installation of such class for an hour each and every one Lang .