Paper Title:

Characteristics of High Frequency Peening Methods and their Effects on the Fatigue Strength of Welded Details

Periodical Key Engineering Materials (Volumes 348 - 349)
Main Theme Advances in Fracture and Damage Mechanics VI
Edited by J. Alfaiate, M.H. Aliabadi, M. Guagliano and L. Susmel
Pages 429-432
DOI 10.4028/www.scientific.net/KEM.348-349.429
Citation Imke Weich et al., 2007, Key Engineering Materials, 348-349, 429
Online since September, 2007
Authors Imke Weich, Thomas Ummenhofer
Keywords Crack Initiation, Fatigue Strength, High Frequency Impact Treatment (HiFIT), Peening, Residual Stress, Ultrasonic Impact Treatment (UIT), Weld Improvement Methods
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Abstract

Research has been initiated on the effects of high frequency peening methods on the fatigue strength. These methods combine an improvement of weld toe profile with an initiation of compressive residual stresses and surface hardening. The effects of two techniques, High Frequency Impact Treatment (HiFIT) and Ultrasonic Impact Treatemnt (UIT) are compared. Laser measurements of the weld seam prove that both methods increase the overall weld toe radii. Further, residual stress measurements verify the introduction of compressive residual stresses at least up to a depth of 1 mm. The values meet the yield strength combined with an increase of the surface hardness. These material mechanical effects cause an increased crack resistance. Crack detection methods prove that the material mechanical effects yield to a retarded crack initiation. Experimental results show that these effects lead to a significant increase of the fatigue strength and reduced slopes of the SN-curves.