Assessment of the possibility of increasing the carburizing temperature of PYROWEAR 53 steel

Abstract

PYROWEAR 53 steel is a special carburizing steel used mainly for the production of machine parts for the aviation industry. Machine parts are surface-strengthened in the carburizing process and subsequent heat treatment (hardening, freezing, and low tempering). The carburizing temperature recommended and used in industrial practice is 921 °C. After saturating the surface layer with carbon, it is recommended to reheat for hardening and cooling in oil. This work assessed the possibility of increasing the carburizing temperature and hardening the layer immediately after saturating the surface layer with carbon, after cooling to the recommended hardening temperature of 913 °C. The carburizing process was carried out using the LPC (low-pressure carburizing) FineCarb technology. The condition for increasing the carburizing temperature was to maintain the required grain size of the prior austenite—G6. This study examined the tendency to grow the austenite grain and determined the highest austenitization temperature ensuring the required grain—G6. At this temperature, the carburizing process then heat treatment were carried out in accordance with the requirements of manufacturers of machine parts for the aviation industry. The microstructure of the layer, its phase composition, the content of retained austenite, the value of residual stresses and surface hardness, and its changes at depth were determined.