Microstructure of VC layer prepared by TD salt-bath vanadizing on 40Cr steel surface

doi:10.13251/j.issn.0254-6051.2020.07.036

Abstract

Abstract: In order to prolong the service life of gear steel, 40Cr steel was selected as substrate material to prepare the VC (vanadium carbide) vanadizing layer by TD (thermal diffusion) salt-bath vanadizing. The thickness of the VC layers formed by vanadizing in salt-bath at 900-1050 ℃ for 6 h was measured, and the microstructure, phases and hardness of the VC vanadizing layers were analyzed by metallographic microscope, scanning electron microscope, X-ray diffraction and Vickers indenter. The results show that the thickness of the VC layers on 40Cr surface is 5-50 μm, and the treatment temperature difference causes migration of the vanadizing layer microstructure in different degrees. The vanadizing layers are mainly composed of VC phase and a small amount of α-Fe phase, and the VC grain growth has two preferential orientations of VC(111) and VC(200). The preferential orientations are weakened with the increase of treatment temperature, and the surface hardness of the substrate is improved in different degrees by the vanadizing layers.

Key words: 40Cr steel, TD salt bath vanadizing, VC layer, microstructure, phase

CLC Number:

TG161

Lei Fengrong, Li Hui. Microstructure of VC layer prepared by TD salt-bath vanadizing on 40Cr steel surface[J]. Heat Treatment of Metals, 2020, 45(7): 177-182.

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