Parameters of wear resistance of surfacing steels for restoration of stamps

Abstract

Summary: Problem. Stamps of hot deformation work in very harsh conditions, characterized by: high operating stresses, the levels of which approach the yield strength of die steels; high heating temperatures; cyclic action of stresses from alternating forces at deformation; thermal stresses, which are determined by the conditions of heating and cooling of the dies; chemical interaction, especially manifested in the process of pressing and stamping. The purpose of this work is to analyze the calculated criteria of the intensity of wear to predict the wear resistance of alloy steels and to show their suitability for the assessment of wear resistance under high temperatures and cyclic stresses for working sections of die tools and rolling rolls used in machining hot metal. Estimation of the calculated values of the effect of temperature on the fracture toughness according to the criteria of J. Malkin and A.S. Tetelman showed the following for alloy steels with metastable austenite. Since for the conditions of molecular-mechanical wear of the working sections of the dies, the coefficient of wear resistance is K ≈ KС2, the increase in the КС when using steels with metastable austenite will change the ratio. At close values of the contact pressure in the friction pair, the formation of the critical length crack increases with the increase of the effective surface energy. Thus, the fracture toughness rates (KC, J, δC), and hence the wear resistance, of secondary hardening steels and steels with metastable austenite are higher than those of martensitic alloy steels and instrumental ones. The following have been shown – the residence time of the metal in the area of plastic deformation is about an order of magnitude less than the total duration of the contacting areas of the friction pair; – the coefficient of variation of wear indicators decreases with increasing proportion of meta-stable austenite in the original structure of the weld metal; – friction heat resistance of economically alloyed alloy steels of the C-Cr-Mo-Ti system is above the similar characteristics of the welded metal type 35V9X3F.