不锈钢低温气体渗碳的C浓度与扩散应力测量与计算  

MEASUREMENT AND CALCULATION OF CARBON CONCENTRATION AND DIFFUSION-INDUCED STRESS IN STAINLESS STEEL AFTER LOW TEMPERATURE GAS CARBURIZING

作　　者：王艳飞[1] 巩建鸣[1] 荣冬松[1] 高峰[1] 

机构地区：[1]南京工业大学机械与动力工程学院,南京211816

出　　处：《金属学报》2014年第4期409-414,共6页Acta Metallurgica Sinica

基　　金：江苏省普通高校研究生创新计划资助项目CXZZ12_0420~~

摘　　要：开展316L奥氏体不锈钢块状试样低温气体渗碳实验,测量渗碳层内沿深度方向的C浓度和应力的大小及分布;基于应力-扩散耦合作用理论,建立渗碳后渗碳层内的C浓度和应力分布的计算模型,利用该模型计算上述渗碳实验后试样沿深度方向的C浓度和应力分布,并将模型计算结果和实验结果进行比较.结果表明,低温气体渗碳后钢在表层产生一层含高C浓度的渗碳层,渗碳层内重现高的压应力,C浓度和压应力均在表面处最大,随着深度的增加而逐渐降低,压力和浓度的大小之间呈直线关系;考虑应力-扩散的耦合作用的扩散计算模型计算得到的C浓度分布和实验测量结果符合的较好,表明扩散引起的应力在低温气体渗碳的C扩散中扮演重要角色;扩散压应力的产生显著增加了C的表观扩散速度,在低温气体渗碳等类似的渗碳或氮的扩散机制研究中,需考虑扩散引起的扩散压应力与扩散之间的相互作用关系.Low temperature gas carburizing has been established as a surface hardening process to improve the wear and fatigue resistance of austenitic stainless steel. In the gas carburizing treatment of stainless steel at low temperature, carbon diffuses into the steel to a depth up to dozens of or even hundreds of micrometers. In industrial practice, it would be useful to establish a model that can predict the carburizing depth from carburizing condition. However, to date a satisfactory model does not exist, and the classic Fick＇s law has been proved to be inaccurate to describe the carbon diffusion during carburation. It has been observed that the insertion of carbon can lead to the evolution of very high compressive stresses in the surface layer of stainless steel. Since it has well established that the stresses induced by diffusion of atoms can in turn affect the diffusion behavior, the high compressive stresses due to carbon diffusion during carburation are supposed to play a role in the further diffusion of carbon. In this work, 316L stainless steel block specimens were gas carburized at low temperature, and the carbon concentration, diffusion-induced stress along the depth direction of specimens were measured. Based on the coupled stress-diffusion theory, a model was built to calculate the carbon concentration and diffusion-induced stress in the specimens after carburizing. Then the calculated carbon concentration and stress distribution were compared to that obtained by above measurement. The results show as follow： （1） After carburizing, a diffusion layer containing high amounts of carbon and compressive stress was formed near the surface of specimens. The concentration and compressive stress were the maximum at the surface, and decreased with increasing depth. There was a linear relationship between the stress and carbon concentration. With increasing carburizing time, the depth and concentration level of the carbon diffusion layer increased. （2） To describe the carbon diffusion during carburation of

关 键 词：低温气体渗碳 316L奥氏体不锈钢 C浓度 扩散应力 

分 类 号：TG156[金属学及工艺—热处理]