Improving Hardness and Wear Resistance of Sparingly Alloyed High-Strength Steels for Production of Items Operating under Conditions of Intense Abrasive Wear

This article discusses the structural factors influencing the hardness of steel, as well as the methods of improving the hardness and wear resistance of inexpensive sparingly alloyed high-carbon steels suitable for operation under conditions of abrasive wear and high contact stresses. The mechanism of increasing the hardness by multiple (cyclic) deep cold treatment of martensite hardened high carbon steels is analyzed. It has been demonstrated that fourfold deep cold treatment (with cooling to –70°C) of rolls from cheap low alloy 170Cr2V steel increased their hardness from 58–59 HRC to 67–68 HRC, exceeding the specifications of the best foreign analogs. Quenching with rapid electric heating is described. It has been found that quenching of steel products with rapid electric heating by high frequency current (HFC), power frequency currents (PFC), and passing current makes it possible to increase their hardness by 2–4 HRC in comparison with quenching by relatively slow furnace heating. At the same time, the more dispersed the initial structure of ferrite–cementite mixture and the finer the cementite plates, the higher is the increased in hardness upon quenching with rapid electric heating. The influence of extra low tempering on steel hardness has been analyzed, and it is demonstrated that, in order to achieve high hardness, it is desirable to apply extra low tempering of high carbon martensite quenched at 100–140°C, which promotes creation of carbon nano-heterogeneity and makes it possible to additionally increase the hardness of low alloy high-carbon steels by 1.5–2.0 HRC.