齿轮渗碳工艺的设计

本文首先介绍了渗碳齿轮热处理中存在的技术问题,而后针对这些技术问题讨论了齿轮渗碳工艺的设计原则。作者认为常用齿轮渗碳是一个混合控制过程。为了强化渗碳过程,渗碳初期要增大相界面渗碳反应速度;中、后期应提高碳在奥氏体中扩散通量。文中还介绍了如何根据表面硬度和其它性能要求,确定渗碳后表面碳含量 C_S;根据 C_S 和渗层厚度,考虑到非平衡渗碳和钢的化学成分选择气氛的控制参数;讨论了变碳势渗碳工艺参数的确定原则及其对渗碳结果的影响。提出了中温渗碳、炉内预冷和热油—空气分级淬火及控制渗层厚度和显微组织等措施以减少齿轮热处理变形。

Design of Carburizing Technique for Gears

The authors introduced some technical problems in the heat treatment of gears carburizing at first,then discussed the designing principles in carburizing technique of gears.In author's opinion,the carburization of common gears is a mix-controlling process and in order to speed it,in the early stage the reac- tive rate in phase boundary should be increased,at the medium and the final stage the diffusion flux of carbon in austenite should be enlarged.The paper also told how to determine the surface carbon content(C_S)of parts after carburizing by the surface hardness and other property requirements.Based on the C_S and case depth,considering non-equilibrium carbttrization and the con- trolling parameter of chemical composition selection of steel.Finally,inve- stigated the principle for determining the process parameters of the two-step carburization and its effect on the result of the carburization.Recommended some steps for diminishing distortion of gear carburizing,such as medium tem- perature carburizing,pre-cool within the furnace,marquenching in the hot oil- air,controlling case depth and the microstrueture et al.