Induction Surface-Hardened 45C8 Carbon and EN47 Spring Steels for Wear-Resistant Applications

This study investigates the induction hardening characteristics and wear performance of 45C8 carbon steel and EN47 spring steel. Optical microstructures of hardened steels revealed that martensite formed due to the quenching (faster than critical cooling) involved in induction hardening. The grain size of hardened EN47 steel was finer, and hardness was higher than that of carbon steel due to its higher carbon content and alloying elements. The depth of the hardened layer in both steels was almost equal (~1.1 mm). Slurry erosive wear tests were carried out using a slurry pot tester to characterize the steel’s induction hardening. The slurry erosion resistance, assessed by cumulative mass loss, of the hardened EN47 spring steel was higher than the carbon steel due to its high hardness and toughness. Predominantly, the craters, microcutting, and plowing eroded the material for unhardened steels, while indentations and pullouts were also responsible for the material removal from the hardened steels. From the fractographic analysis, the ductile mode of erosion for unhardened steel and mixed (ductile + brittle) erosion mode for hardened steel can be established.