Process of surface micro melting and polishing on 3Cr2Mo steel with scanning electron beam and its effect on the microstructure and properties of hardening layer

摘要

Process of surface micro melting and polishing can reduce surface roughness so as to improve the surface mechanical properties. Process of surface micro melting and polishing on 3Cr2Mo steel is re-searched in this paper and the microstructure and properties of surface hardening layer are analyzed. The results show that surface roughness is reduced by 41.1% and surface average hardness is 724HV after the sample whose surface roughness is 1.472μm is processed by surface micro melting and polishing. The cross-section microstructure is composed of hardened zone, transition zone and matrix. The distribution of cross-section morphology of hardened zone is like "W"; The microstructures of hardened zone are composed of acicular martensite and lath martensite; The microstructures of transition zone are composed of cryptocrystalline martensite, residual austenite, troostite and tempered sorbite; The deepest hardened zone reaches about 520μm; The change of microhardness (650HV～715HV) is not obvious which is 2.26～2.4 times as hard as matrix.