Estudo das propriedades mecânicas e tribológicas do aço ABNT M2 submetido aos tratamentos térmicos e criogênico

Abstract

Rapid steels are commonly used for tool making and are used under severe conditions, have high hardness, good wear resistance and high toughness. For this, it is important to study innovations in thermal treatments such as cryogenics. Recent studies bring this new treatment that uses extremely low temperatures, since in the range of - 80ºC to -190ºC occurs the transformation of the retained austenite in martensite and the precipitation of fine carbides. In this way, the combination of conventional heat treatments together with cryogenic treatment plays an important role in improving the quality of mechanical components. For this reason, the present work aims to compare the performance of the combination of quenching, tempering and cryogenic varying the parameters of time, temperature and quantity of treatments to investigate which aspects influence the mechanical and tribological properties of ABNT M2 high speed steel. The methodology used in the study was experimental research, where the samples were austenized at 1180ºC and quenched in oil, cryogenictreated at -181ºC during 24h with a ramp of -0.5ºC/min and the tempering was done at 550ºC for 2h. After that, were done the mechanical tests of hardness, microhardness, abrasion and charpy and the metallographic tests of optical microscopy and scanning electron microscopy to analyze the material’s microstructure and fracture. The steel that received double cryogenic treatment before double tempering obtained the best improvement in in their mechanical and tribological properties.