摘要
本文用金相显微镜、X射线衍射仪、电子探针及精密天平研究了离于硫氮碳共渗化合物层的形成动力学、组织结构以及硫、氮、碳分布。试验表明,离子硫氮碳共渗试样表面上形成疏松多孔状的硫化铁(FeS),其厚度和增重量与处理时间的平方根成正比关系。次表面化合物层主要由γ′-Fe_4N和ε-Fe_(2～3)(N,C)组成。45钢540℃×6h离子硫氮碳共渗时,次表面层化合物组成从外到内是按照γ′_多+ε_少→γ′_少+ε_多→γ_多+ε_少→γ′_少+ε_多顺序分布。在离子硫氮碳共渗层中,硫主要集中在表面疏松层中和次表面化合物层与表面疏松层之间的界面处;氮的最大浓度出现在次表面化合物层最外侧上;碳浓度峰值,短时共渗,在次表面外侧上,而延长共渗时间,其峰值朝内移动,并出现两个峰值。
This paper deals with the forming dynamics, the structure and the distributon of sulphur, nitrogen, carbon in the compound layer formed in the ion-sulfonitrocarburizing process by means of the metllographic micro-scope, X-ray diffraction analysis, electron-microprobe and a precise balance. The experiment showed that a loose and porous iron sulphide (FeS) is formed in the outmost surface, the thickness and the added weight of which are directly proportional to the square root of the process time.The inner compound layer of the specimen is composed mainly of γ'-Fe4N and ε-Fe_(2-3)(N, C). In the course of ion-sulfonitrocaburizing of 45 steel at 540℃×6h, the inner compound layer of the specimen is distributed in accordance with the order of γ'_(more)+e_(less)→γ'_(less)+ε_(more)→γ'_(more)+ε_(less)→γ'_(less)+ε(more). In the layer of ion-sulfonitrocarburizing, the sulphur is concentrated on the porous outmost surface and the boundary between the inner compound layer and the porous outmost surface of the specimen, and the highest nitrog en content appears at the outmost portion of the inner compound layer of the specimen, and the highest carbom content lies in the outmost portion of the inner compound layer of the specimen when the ion-sulfonitrocarburizing time becomes shorter, while the highest carbon content does not lie in the outmost portion of the inner compound lay of the specimen,with its peak value moving inward and two peak values are appeared as the ionsulfontirocarburizing time increases.
