Electrical and magnetic techniques for monitoring arc behaviour during VAR of INCONEL1 718: Results from different operating conditions

Novel instrumentation and computer modelling are described which have been developed to detect and interpret current flows and magnetic fields during VAR. Results from different operating conditions during VAR of 20″ diameter ingots of INCONEL 718 at Special Metals Wiggin Ltd., Hereford are presented and discussed with reference to macrostructural findings. It is shown that the results support the viability of the measurement techniques, and that the techniques are capable of detecting subtle changes in arc behaviour. Freckles were formed under one set of experimental conditions, and it is shown that the distribution of the radial location of the arc centre (obtained from the magnetic field analysis) may help to explain this.