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High‐Strength Steels in Welded State for Light‐Weight Constructions under High and Variable Stress Peaks
Author(s) -
Kaufmann H.,
Sonsino C.M.,
Demofonti G.,
Riscifuli S.
Publication year - 2008
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.200806142
Subject(s) - welding , fatigue limit , structural engineering , stress (linguistics) , high strength steel , amplitude , ultimate tensile strength , materials science , engineering , composite material , physics , linguistics , philosophy , quantum mechanics
In design codes (Eurocode, British Standard and others) for the dimensioning of welded joints, no distinction is made between low, medium and high strength steels. Because of a lack of general knowledge about the benefits of high‐strength steels and also because of missing information in design codes, in many cases design engineers still use low or medium strength steels (R p0.2 < 400 MPa) and compensate for high loads under constant or variable amplitude loading or overloads by increasing dimensions. Given this situation, it was deemed necessary to establish criteria for the design of light‐weight welded constructions under high and variable stress peaks using new classes of high strength steels, such as S355N (normalized), S355M (thermomechanically treated), S690Q (water quenched) and S960Q (water quenched), and to perform more reliable evaluations of the fatigue performance of high strength steel structures subjected to complex loading with regard to light‐weight design and economics. For the comparison of the fatigue strengths of the investigated steels the notch factors present were taken into account. Additionally, the real damage sums were determined in order to give recommendations for the fatigue life estimation. Under constant amplitude loading, no significant difference in the bearable local stress amplitudes for the butt welds can be detected for the four investigated steels. Under variable amplitude loading, the butt welded (lower notch factor) high strength steel S960Q has advantages in the case of the normal Gaussian spectrum and in the case of overloads, especially under pulsating loading. For the transverse stiffeners (high notch factor), slight advantages for the high strength steel S960Q exist, only in the case of pulsating overloads. However, the advantages of high strength steels in case of static loading are indisputable. In most of the investigated cases, overloads lead to a benefit in fatigue life.