The Paton Welding Journal, 2019, №02



2019 №02 (05)

DOI of Article 10.15407/tpwj2019.02.06

2019 №02 (07)

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The Paton Welding Journal, 2019, #2, 35-40 pages
 
Journal The Paton Welding Journal
Publisher International Association «Welding»
ISSN 0957-798X (print)
Issue #2, 2019 (March)
Pages 35-40

Methods of evaluation of increase of fatigue resistance in butt welded joints of low-carbon steels after high-frequency mechanical peening

V.A. Degtyarev

G.S. Pisarenko Institute for Problems of Strength of the NAS of Ukraine 2 Timiryazevskaya Str., 01014, Kyiv, Ukraine. E-mail: degtyarev@ipp.kiev.ua

There was investigated an effect of modes of high-frequency mechanical peening on increase of fatigue resistance of butt welded joints of steel St3sp (killed). Different technology of sample preparation for investigation allowed determining that a quantitative contribution in rise of fatigue limit of welded joints of residual compression stresses, deformation hardening of surface layer of a groove formed after peening of a narrow zone of weld fusion with base metal, and change of stress concentration after high-frequence mechanical peening makes 57, 37 and 6 %, respectively. It is shown that there is a correlation between the groove depth and depth of plastically deformed layer of material. The procedure was proposed for determination of the fatigue limits of butt welded joints after different modes of peening on groove depth and plastically deformed layer of material, using the experimental data of microhardness measurement as well as the change of amplitude of working tool oscillation in the investigated range. A depth of groove was determined depending on rate of high-frequency mechanical peening and amplitude of working tool oscillations as well as change of sample fatigue limit due to different technology of their manufacture. It is shown that increase of peening rate independent on the working tool oscillation amplitude promotes decrease of efficiency of improvement of welded joint fatigue resistance and at 0.4 m/min rate the fatigue limit from deformation hardening and total effect of all factors typical for high-frequency mechanical peening rises by 11 and 26 %, respectively. 14 Ref., 4 Tables, 7 Figures.
Keywords: welded joint, fatigue limit, groove depth, rate of high-frequency mechanical peening, plastically deformed layer, microhardness
 
Received: 24.10.18
Published: 11.03.19
 

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