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Welding procedures for fatigue life improvement of the weld toe
Volvo Construction Equipment AB.ORCID iD: 0000-0002-5290-6619
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. (KTH Weld Mechanics Group)ORCID iD: 0000-0003-4465-9299
Volvo Construction Equipment AB.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. (KTH Weld Mechanics Group)ORCID iD: 0000-0003-4180-4710
2016 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 60, no 3, 573-580 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents the results of an experimental study of gas metal arc welded, GMAW, cruciform joints made of common construction steel S355. The hypothesis is that smooth undercuts in as welded conditions can give enhanced fatigue properties similarly as post treated welds. Undercuts are generally seen as a defect or imperfection. Welders try to avoid these and repair them when they occur, which result in increased production lead time. Post weld improvement methods i.e. grinding or high-frequency-impact treatment (HFMI) as fatigue-enhancing post-treatment methods enforce amongst other effects a certain smooth undercut-shaped groove in the treated weld toe region. The obtained shallower weld toe transition reduces the geometrical notch effect and increases fatigue strength. This paper presents a study whereas welded specimens with a weld toe geometry similar to what is obtained by weld toe grinding or HFMI-treatment, has been produced, fatigue tested and analyzed. The improvement of the fatigue strength is comparable to post-weld treated specimens. It has proven to be an efficient way to achieve high-quality welds without introducing any additional operations in production, thus enabling weight reduction using cost-effective methods.

Place, publisher, year, edition, pages
Springer Publishing Company, 2016. Vol. 60, no 3, 573-580 p.
Keyword [en]
Weld toes, Weld shape, Fatigue improvement, Fillet welds, GMA welding
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering; Solid Mechanics; Production Engineering
Identifiers
URN: urn:nbn:se:kth:diva-188224DOI: 10.1007/s40194-016-0309-9ISI: 000379434400016ScopusID: 2-s2.0-84966378339OAI: oai:DiVA.org:kth-188224DiVA: diva2:934610
Funder
VINNOVA
Note

QC 20160610

Available from: 2016-06-09 Created: 2016-06-09 Last updated: 2016-08-12Bibliographically approved
In thesis
1. Fatigue properties of cut and welded high strength steels: Quality aspects in design and production
Open this publication in new window or tab >>Fatigue properties of cut and welded high strength steels: Quality aspects in design and production
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This doctoral thesis concerns fatigue of welded structures. Welding is one of the world’s most common joining methods and it is frequently used in several structural applications in many fields. Some examples are construction vehicles, loader cranes, trucks, busses, forestry and agricultural machines, bridges and ships. Since these structures are subjected to repeated loading, fatigue is the most common cause of failure.

A novel numerical algorithm has been developed which assesses the welded surface and calculates and quantifies weld quality parameters and the presence of defects which are critical in fatigue applications. The algorithm is designed for implementation in serial production. It will provide robust and reliable feedback on the quality being produced, which is essential if high strength steels are utilized.

Two welding procedures which can increase the weld quality in as welded conditions have been assessed. These procedures utilize welding in different positions and pendling techniques, which can be accomplished using the existing welding equipment. It was found that by using these methods, the fatigue strength can be increased compared to normal weld quality.

Furthermore, two fatigue assessment methods ability to account for increased weld quality in low cycle and high cycle fatigue applications has been studied. One of these methods showed sufficient accuracy in predicting the fatigue strength with small scatter and also account for increased weld quality.

When implementing thinner high strength steels, the overall stress level in the structure increase. Therefore, other locations such as the steel cut edges may become critical for fatigue failure unless they are not designed and manufactured with the same quality as the welded joint. The influence of surface quality on cut edges was studied and the fatigue strength was estimated using international standards and a fatigue strength model for cut edges.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2016. 56 p.
Series
TRITA-AVE, ISSN 1651-7660 ; 2016:21
Keyword
Welding, Fatigue assessment, Cutting, Weld quality, Fatigue design, Fracture Mechanics
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-188225 (URN)978-91-7729-027-8 (ISBN)
Public defence
2016-08-26, F3, Lindstedtsvägen 26, Stockholm, 09:00 (English)
Opponent
Supervisors
Projects
WIQLIGHTSTRUCTONWELD
Funder
VINNOVA
Note

QC 20160613

Available from: 2016-06-13 Created: 2016-06-09 Last updated: 2016-06-13Bibliographically approved

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Åstrand, ErikStenberg, ThomasBarsoum, Zuheir
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