The Paton Welding Journal, 2013, №01



2013 №01 (09)

2013 №01 (01)

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The Paton Welding Journal, 2013, #1, 47-51 pages  

INCREASE OF FATIGUE LIFE OF WELDED T-JOINTS WITH LACK OF ROOT PENETRATION USING HIGH-FREQUENCY MECHANICAL PEENING

S.A. SOLOVEJ

E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
 
 
Abstract
Represented are the results of fatigue tests of welded T-joints from low-alloyed steels 09G2S, 10KhSND and 15KhSND. Manufacture of such joints embedded a structural lack of root penetration of 3 x 3 mm cross section along the whole length of the welded joint. The purpose of present study is an experimental evaluation of effect of extensive lacks-of-penetration on fatigue life of the welded joints on low-alloyed steels strengthened by high-frequency mechanical peening which used in manufacture of critical welded metal structures. Testing of welded specimens was carried out with zero-to-tension stress cycle at 5Hz frequency. It is shown that the fatigue life of high-loaded T-joints from low-alloyed steels strengthened by given technology and containing extensive structural lacks of root penetration of 3 x 3 mm cross section, is in a range of spread of experimental data for strengthened welded joints made with full penetration. Failure of the specimens at that takes place from the lack of root penetration along the rib and their fatigue life rises up to 10 times in comparison with that of unstrengthened specimens with full penetration. As was stated, the presence of structural lack-of-penetration in the unstrengthened high-loaded T-joints, cross ribs of which do not transfer main load, provides no effect on the fatigue life since formation and propagation of cracks take place on zone of weld metal to base metal transfer. 13 Ref., 4 Figures.
 
 
Keywords: welded metal structures, low-alloyed steels, T-joint, fatigue life, high-frequency mechanical peening, fatigue
 
 
Received:                14.11.12
Published:               28.01.12
 
 
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