Alternative Mechanical Surface Treatments: Microstructures, Residual Stresses & Fatigue Behavior

Author:  Igor Altenberger
Source:  Conf Proc: ICSP-8 Sept. 16-20, 2002 Garmisch-Partenkirchen, Germany
Doc ID:  2002055
Year of Publication:  2002
Author Igor Altenberger* Department of Materials Science & Engineering, University of California, Berkeley, CA, USA *Now at: Institute of Materials Technology, University of Kassel, Kassel, Germany Abstract In comparison to the most widely used mechanical surface treatment shot peening, common alternative methods such as deep rolling and less common methods such as laser shock peening, ultrasonic shot peening, water peening or various burnishing methods have been introduced into practical applications only rarely, or for highly specialized components, or are just on the verge from laboratory research into larger scale applications. However, in the future it is expected that these so called "alternative" mechanical surface treatment methods will be more widespread owing to superior benefits for materials' behavior, improving process technology and dramatically decreasing costs. The basic principles of all mechanical surface treatments are well known: In all cases a localized elastic-plastic deformation in near-surface regions leads to the formation of compressive residual stresses and severe microstructural alterations (usually associated with intense work hardening), enabling the thus strengthened near-surface regions to withstand higher resistance against fatigue crack initiation and propagation. Moreover, in some cases, additional effects may give rise to further fatigue life/strength enhancement such as surface smoothening or deformation-induced phase transformations. At closer look, near surface properties and thus fatigue behavior might be distinctly different for different surface treatment methods. It is the objective of this contribution to shed some light on these basic effects and to propose some basic guidelines for the utilization of 'optimized' treatments from a materials science perspective.

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