APPLICATION OF BARKHAUSEN NOISE MEASUREMENTS FOR THE EVALUATION OF SURFACE INTEGRITY OF COMPONENTS: SOME CASE STUDIES
G. V. Prabhu - Gaunkar*, and Robert M. Fix** * Department of Metallurgical Engineering & Material Science, Indian Institute of Technology, Powai, Mumbai-400 076, India ** American Stress Technologies Inc., 61, McMurray Road, Pittsburgh, PA 15241, USA
Surface micro - structure and residual stress pattern can have important consequences on the performance of components subjected to fatigue loading and to corrosive environments. Barkhausen Noise (BN) measurements can be used as an effective tool to monitor the near surface residual stresses in Ferromagnetic materials and to detect micro - structural inhomogenities produced during processing or service exposure of components. The BN measurements consists of monitoring electrical pulses produced as a result of the magnetic domain wall movements produced in the material under testing. The intensity of the BN signals depends on the stress levels and micro - structure of the material. Successful application of the method requires stress response calibration curves determined on a material having processing history, micro - structure and chemical composition identical to that of the component surface. The paper gives case studies on application of BN measurements for the evaluation of the surface integrity of typical components such as Gears and welded joints involving residual stress and micro - structural variations.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 3, pages 1647 - 1654 Publisher:Ashgate Publishing Company
NDTnet
