Issue 42

M. Peron et alii, Frattura ed Integrità Strutturale, 42 (2017) 205-213; DOI: 10.3221/IGF-ESIS.42.22 205 Local strain energy density for the fatigue assessment of hot dip galvanized welded joints: some recent outcomes M. Peron, S.M.J. Razavi ,F. Berto, J. Torgersen, F. Mutignani Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology (NTNU), Richard Birkelands vei 2b, 7491, Trondheim, Norway. mirco.peron@ntnu.no, javad.razavi@ntnu.no, filippo.berto@ntnu.no , jan.torgersen@ntnu.no A BSTRACT . Since in literature only data about the effect of the hot-dip galvanizing coating on fatigue behavior of unnotched specimens are available, whereas very few for notched components and none for welded joints, the aim of this paper is to partially fill this lack of knowledge comparing fatigue strength of uncoated and hot-dip galvanized fillet welded cruciform joints made of structural steel S355 welded joints, subjected to a load cycle R = 0. 34. The results are shown in terms of stress range Δ σ and of the averaged strain energy density range W  in a control volume of radius R 0 = 0.28 mm K EYWORDS . Hot-dip galvanized steel; High cycle fatigue; Fillet welded cruciform joint; SED. Citation: Peron, M., Razavi, S.M.J., Berto, F., Torgersen, J., Mutignani, F., Local strain energy density for the fatigue assessment of hot dip galvanized welded joints: some recent outcomes, Frattura ed Integrità Strutturale, 42 (2017) 205-213. Received: 15.07.2017 Accepted: 31.07.2017 Published: 01.20.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION orrosion is one of the main issue affecting metallic materials such as iron and steel, and several technique to prevent corrosion are available in literature, especially surface treatments. Among all, hot-dip galvanizing has been widely used, with great successes in a large amount of worldwide applications. Hot-dip galvanization involves the coating of the base material with a zinc layer and several works investigate the influence of different bath composition on mechanical properties [1, 2] and the effect of this protective film on static and fatigue behavior. Whilst tensile properties are not greatly affect, except for the yield stress, fatigue strength is reported to be reduced when the coating thickness exceed a threshold value [3], calculated employing the Kitagawa–Takahashi diagram. Moreover, Bergengren and Melander [4], found an increase in the detrimental effect on fatigue life increasing the zinc layer thickness, but, nevertheless, contrasting results were obtained by Browne et al., [5], and Nilsson et al., [6], that did not find any correlation in terms of loss of the fatigue strength due to the coating thickness. Furthermore, hot-dip galvanization is still an attractive topic, as proved by several recent studies, such as [7-10]. However, the works just mentioned refer to unnotched specimens and very few results are available for notched components. In fact, at the best of author’s knowledge the only data available in literature for notched components are due to Huhn and Valtinat [11], that examined S 235 JR G2 plates with holes and bearing-type connections with punched and drilled holes. Besides this lack of C