Examination on the use of acoustic emission for monitoring metal forging process: A study using simulation technique

Physical models for acoustic emission (AE) event rate monitoring were introduced and expressions developed to predict AE event rate activity from such parameters as applied stress, strain and strain-rate. The models were incorporated into a visco-plastic finite-element simulation program, and the acoustic emission signals generated during upset forging and disk forging operations were predicted. The results agreed well with experimental data for these processes, which leads to confidence in the forms and implementations. Simulation results are presented for upsetting operations on a typical C-Mn type steel for various friction and die geometry conditions. The AE model predictions compare well with the available experimental results reported in the literature and demonstrate that AE signatures can be reliably simulated. The signatures predicted for metal forging are fairly insensitive to processing parameter changes which suggests that AE event rate monitoring may not be well suited for monitoring changes in microstructure and friction during forging. Some very initial studies of event spectral analysis have been performed that suggest that AE spectral features may be sufficiently dependent on structure and loading to warrant further examination for application of process monitoring.