Electron microscopy characterization for microstructure of Al-bearing high-boron high-speed steel

doi:10.13251/j.issn.0254-6051.2022.07.031

Abstract

Abstract: Microstructure and boron carbide type of Al-bearing high-boron high-speed steel (BHSS) were analyzed by a combination of several microscopy characterization techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The results show that the microstructure of as-cast Al-bearing high-boron high-speed steel is ferrite and network boron carbide, and the type of boron carbide includes Fe₂B (Cr-rich), FeMo₂B₂ (Mo-rich) and Fe₃C (Cr-Mo). After heat treatment, the matrix microstructure is martensite, and the network boron carbide is broken and spheroidized, and the type of boron carbide includes Fe₂B (Cr-rich), (Fe, Cr)₂₃C₆ (Cr-Mo), and FeMo₂B₂ (Mo-rich). The rupture of network boron carbide after heat treatment is due to the decomposition of Fe₃C (Cr-Mo) into (Fe, Cr)₂₃C₆ (Cr-Mo) and FeMo₂B₂(Mo-rich). The crystal structure of boron carbide obtained by TEM analysis is consistent with the conclusion of EBSD.

Key words: high-boron high-speed steel, heat treatment, microstructure, electron microscopy, boron carbide

CLC Number:

TG142.1

Dong Yanchao, Ma Tiejun, Fu Hanguang, Jin Tounan, Yuan Naibo, Jin Tounan. Electron microscopy characterization for microstructure of Al-bearing high-boron high-speed steel[J]. Heat Treatment of Metals, 2022, 47(7): 177-182.

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