Investigation of sound phenomena during quenching process

The purpose of controlling the hardening process by selecting the most suitable quenching parameters is to ensure the required hardness and the residual stresses, particularly in the surface layer of a machine part. The article describes the system designed to capture acoustic emission in different quenching media, which includes the assessment of hardening efficiency during the quenching process itself. Analysis of these acoustic emission signals can give useful information and confirm the differences caused by different quenching conditions. The sound pressure signal, as the variation of time dependent amplitude at different frequencies, is presented by 3D diagrams. Analysis of the quenching results, i.e. cross-sectional hardness of the workpiece and the acoustic emission signals during the process itself, leads to a new approach in the monitoring of the hardening processes.