Eutectic resolidification and ultrafast self-quenching of the microstructure in the surface layer of high-speed steel by scanning electron beam treatment

• Published in: Vacuum 2025-01, Vol.231, p.113765, Article 113765
• Main Authors: Wei, Deqiang, Mo, Zhenzhao, Lu, Jian, Li, Xinkai, Weng, Yitao, Ren, Xulong, Hu, Chaofan
• Format: Article
• Language: English
• Subjects: Eutectic resolidfication; M2 high-speed steel; Microstructure; Scanning electron beam; Self-quenching
• ISSN: 0042-207X
• DOI: 10.1016/j.vacuum.2024.113765

Improving the service life and efficiency of high-speed steel (HSS) tools remains a formidable challenge. Herein, scanning electron beam (SEB) was employed to modify the surface of M2 HSS. Results revealed that SEB induced eutectic resolidification and ultrafast self-quenching of microstructure in surface layer of HSS. The melted layer exhibited a microstructure comprising martensite, residual austenite, dispersed finely rod-like MC and lamellar M2C eutectic carbides along grain boundaries. Martensite and eutectic carbide grid structure significantly enhanced the hardness and wear resistance of surface layer. Compared to substrate, the microhardness of SEB sample was elevated by more than threefold, reaching 914.7HV0.2, which exceeded the hardness (828.6HV0.2) of conventional quenching treatment. Notably, the wear volume of SEB sample had been reduced to 0.54 × 10−11 m3, resulting in a wear resistance that was 3.8 times greater than that of quenched sample. •An efficient surface modified method for M2 high-speed steel was presented.•Microstructure of M2 high-speed steel was investigated following scanning electron beam.•The mechanism of eutectic resolidification and self-quenching has been elucidated.•SEB sample demonstrates a 3.8-fold enhancement in wear resistance compared to the quenched sample.