Two methods of hardness determination for modern materials by an automatic indentation

Abstract

By method of an automatic indentation of various type and structural state materials (37 materials) it is established that the values of hardness determined by a technique of International Standard H_IT=0,418 F_max/h_c² and with use of work W_c, executed enclosed force F_max on replacement by an indenter of a material in contact area of print H_Wc=0,125 W_c/h_c³, not always coincide. Distinction between them ΔH=H_IT - H_Wc grows in process of increase of values relative outcontact elastic deformation ε_es and hardness H_IT of a material. On the basis of the received experimental data the explanation of this effect according to which presence of difference ΔH and its value are determined by elastic properties of a material, first of all - value relative outcontact is offered to elastic deformation ε_es of a material which, in turn, is defined by the contact modulus of elasticity E* and a structural state of a material. These three factors in aggregate supervise value of material hardness. By results of the analysis of dependence of absolute hardness values H_IT and value of difference ΔH from values ε_es and H_IT the investigated materials the map of structural states in coordinates _es - H_IT is constructed. The map contains 4 areas, in each of which materials with the certain type of a structural state, limits relative outcontact elastic deformation ε and levels of hardness settle down. The map allows identifying unknown structural state of a material.