Study On Surface Strengthening Of 45 Steel By EDM

With the deep research of EDM technology, it is used widely today. Because EDM has the unique process principle, it is also being used for surface strengthening successfully and favorable benefit has been obtained.EDM machine has become requisite equipment in the workshop of tools and moulds. If the electric-material can be strengthened by using ordinary EDM machine, it will have good potential applications and economical value on the condition of underdevelopment economic in our country.In this paper, experiments of surface strengthening process were made with silicon crystal as electrode material and 45 steel as substrate material on DM7132 precision forming machine. And the element distribution, morphology, performance and the microstructure of strengthening-layer as well as the strengthening mechanism have been studied. Through the analysis of experiment data, the law of influence of strengthening layer and surface quality has been studied under different process parameters such as peak current, pulse width, pulse interval and processing period.By means of detection and analyses of the X-ray diffraction and EPMA, strengthening layer contains Silicon, Ferro and Carbon. The content of Silicon and Ferro is much more than that of substrate material and it is also distributed gradient from the surface to substrate of workpiece. The electrical discharge strengthening is not only a process of electrode's overlaying on the surface of workpiece, but also a complicated physicochemical alloying and metallurgy process of the elements coming from the electrodes, workpiece and the ions coming from the medium in the condition of high temperature and pressure.Experiments of micro-hardness, wearing resistance and corrosion resistance show that all properties are much higher than those of the workpiece material.Experiment and analysis shows that if proper processing conditions and processing time are selected, a certain depth of strengthening-layer can be obtained, which has higher hardness, wearing resistance and corrosion resistance. And surface quality of workpiece will be improved.