Selection and Application of the Optimal Surface Engineering Method to Restore the Properties of Rolling Equipment Elements that Have Been Reduced Due to Violations of Surface Grinding Technology

Abstract

The methods of influence on the material using different energy sources are considered. The role of friction in several technological processes is emphasized. The technological process of heat treatment is proposed, which allowed to restore the properties of rolled rolls that were lost due to incorrect grinding conditions. Application of the proposed technological process has shown that: 40X steel can be hardened to martensite in oil, water, and in a 10 % aqueous solution of NaCI salt, but with different results (i); the most effective hardening mode for 40X steel rolls is quenching with cooling in a 10 % aqueous solution of NaCI salt and subsequent high-temperature tempering, which is ecessary to remove dangerous residual stresses (ii); the structure of the surface working layer of 40X steel rolls, after the selected optimal heat treatment regime, consists of fine-needle martensite and a small amount of Cr carbides (iii); closer to the core of the rolls, in addition to martensite, there are areas of troostite-bainite structure (iv); the resulting structure of the rolled rolls is capable of ensuring their efficient and long-term operation, but under optimal conditions, when the rolls' heating temperatures do not exceed 200 °C, and the proposed temperature conditions are recommended for both operation and routine maintenance associated with periodic restorative grinding of the working surfaces of the rolled rolls (v).