Ultrasound effect on electrospark cementation process

Abstract

The process of carburizing is well-studied and is one of the traditional processes of the thermochemical treatment of steel. The process has disadvantages such as high energy consumption, long exposure time, complicated processing of large products and surfaces. Electrospark deposition with a carbon electrode is proposed as an alternative process. The carburizing extent and the working layer depth can be increased when the process is used in the ultrasonic vibration field. A resonant vibration introducing circuit with a standing wave generated in the specimen tested is implemented to identify the influence of specific ultrasonic wave areas on the hardened layer formed. The highest carbon saturation of the surface layer was found in the standing ultrasonic wave oscillation node area, where cyclic stretching and compression of the medium contribute to the excess phases release. The carbon in the martensite estimated by the c/a ratio was 0.78% by weight. The highest cementite layer depth and transition zone size are in the ultrasonic wave antinode area, where the highest dynamic medium particles displacement is observed under the influence of vibrations. It is shown that the base metal structure component dispersiveness is responsible for the increased hardened layer depth. © Published under licence by IOP Publishing Ltd.