Microstructures and Properties of T1 High-Speed Steel Modified by In Situ Fe-Cr-Ti-C-N Nanocomposite Inoculants

A Fe-based nanocrystalline inoculant is designed and prepared via in situ synthesis based on material thermodynamics, where mechanical grinding in a ball grinder and heating in a vacuum tube furnace are important steps. The microstructure and mechanical properties of T1 high-speed steel (T1 HSS) with and without addition of the inoculant are investigated using high-resolution transition electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Vickers hardness testing (VHT). The Cr7C3 particles in the inoculant near the grain boundary of the Fe3W3C phase serve as a base for martensite and M6C heterogeneous nucleation, thereby increasing the nucleation rate and refining the matrix structure. The T1 HSS with the added inoculant exhibits superior hardness, impact toughness, and wear resistance after tempering treatment compared with the uninoculated control, where the hardness increases from 62.3 to 65.7 HRC with inoculation. Furthermore, the wear rate decreases from 0.0704% to 0.0551%, and the impact energy of T1 HSS after inoculation increases from 36.75% to 22.0638 J cm(-2) under the same experimental conditions.

Automated summary

By adding a Fe-based nanocrystalline inoculant to T1 high-speed steel, the microstructure and mechanical properties of T1 HSS can be improved, leading to increased hardness, impact toughness, and wear resistance. This is achieved by refining the matrix structure and increasing the nucleation rate using Cr7C3 particles near the grain boundary of the Fe3W3C phase, resulting in a decrease in wear rate and an increase in impact energy.