Ultrasonic Impact Treatment For Surface Hardening Of The Aero-engine Material In718

Author:  R. Hessert, J. Bamberg, W. Satzger, T. Taxer
Source:  Conf Proc: ICSP-10 Tokyo, Japan 2008
Doc ID:  2008102
Year of Publication:  2008
ABSTRACT In order to satisfy stringent requirements regarding reliability, minimum weight, high performance, cost-effectiveness and long-term durability, the components of modern aircraft engines must tap the full potential of the materials used. For this reason, there has been a growing interest in work hardening processes applied to the surface layers of highly-stressed components with particular attention drawn towards the optimisation of established techniques such as shot peening and deep rolling as well as the development of new methods. Such a new method is the ultrasonic impact treatment (UIT). UIT is predominantly used in the manual post-weld processing of steels. In addition to the intrinsic local and low loading treatment, UIT is cost-effective and easy to control such that it may be suitable for a wide range of applications. The objective of this work is to describe the potential of applying UIT to the high-strength nickel base alloy IN718. In order to characterise the hardened surface layer, surface roughness measurements and Xray residual stress analyses were taken including experiments to evaluate the thermal stability of selected samples. The results obtained were compared to shot peened and deep rolled surfaces. It was discovered that the UIT technique produces deep surface layer work hardening. The hardening depths and surface roughnesses are similar to that obtained by deep rolling. Therefore all the specific advantages of UIT can be extended to the surface hardening of aero engine components. KEYWORDS Ultrasonic impact treatment, surface treatment, work hardening, residual stresses, IN718

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