High temperature carburizing process of 18CrNiMo7-6 steel in controlled atmosphere

doi:10.13251/j.issn.0254-6051.2022.04.040

Abstract

Abstract: Based on the heat treatment process requirements of heavy load gear for locomotive, pseudo-carburizing process was carried out on 18CrNiMo7-6 steel within temperature range of 920-1050 ℃. The microstructure and mechanical properties of the tested steel after conventional carburizing and high temperature carburizing at different temperatures were compared. Combined with the process simulation results of Aichelin computer aided simulation design software, high temperature carburizing process was developed, and the high temperature carburizing process of the 18CrNiMo7-6 steel gear was carried out, and the microstructure and properties of the gear were compared with those of the conventional carburizing gear. The results show that the comprehensive mechanical properties of the 18CrNiMo7-6 steel are decreased after pseudo-carburizing at different temperatures and time, compared with that before heat treatment, but the comprehensive mechanical properties of the 18CrNiMo7-6 steel can be significantly improved by controlling the cooling process after carburizing. Increasing carburizing temperature and carbon potential can greatly improve carburizing efficiency. The carburizing efficiency of the 18CrNiMo7-6 steel gear is increased by about 65% at the temperature of 1050 ℃. Compared with the conventional carburizing gear, the microstructure, comprehensive mechanical properties and single-tooth bending fatigue strength of the gear are not decreased after high temperature carburizing.

Key words: 18CrNiMo7-6 steel, transformation behavior, high temperature carburization, mechanical properties, single-tooth bending fatigue

CLC Number:

TG156.3

Chen Qiang, Chen Linfang, Yang Minghua. High temperature carburizing process of 18CrNiMo7-6 steel in controlled atmosphere[J]. Heat Treatment of Metals, 2022, 47(4): 231-239.

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