J. Lewandowski et alii, Frattura ed Integrità Strutturale, 48 (2019) 10-17; DOI: 10.3221/IGF-ESIS.48.02 10 Focussed on “Crack Paths” Fatigue crack growth in welded S355 specimens subjected to combined loading J. Lewandowski, D. Rozumek, Z. Marciniak Opole University of Technology, Poland janusz210@wp.pl d.rozumek@po.opole.pl, http://orcid.org/0000-0003-2866-2041 z.marciniak@po.opole.pl, http://orcid.org/0000-0001-7071-4488 G. Lesiuk Wrocław University of Science and Technology, Poland grzegorz.lesiuk@pwr.edu.pl http://orcid.org/0000-0003-3553-6107 R. Brighenti University of Parma, Italy roberto.brighenti@unipr.it, http://orcid.org/0000-0002-9273-0822 ABSTRACT. The paper presents the results of experimental fatigue tests performed on welded S355 specimens subjected to combined bending and torsion loading. In order to analyse how the fillet joints’ shape and the load ratio affect the crack growth, we selected two kinds of fillet shape: concave and convex, and two load ratios, namely R = -1, 0. Rectangular specimens with stress concentrators in the form of the external two-sided blunt notches and fillet welded joint were tested. The test results were compared to experiments conducted on solid specimens without welds. KEYWORDS. Welding; Combined loading; Fatigue crack; Microhardness. Citation: Lewandowski, J., Rozumek, D., Marciniak, Z., Lesiuk, G., Brighenti, R. Fatigue crack growth in welded S355 specimens subjected to combined loadings, Frattura ed Integrità Strutturale, 48 (2019) ww-zz. Received: 15.11.2018 Accepted: 20.12.2018 Published: 01.04.2018 Copyright: © 2019 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. INTRODUCTION any kinds of research are devoted at describing the behaviour of crack growth in structural component [1-6] and joints [7-10]. Fatigue crack growth in welded joints is still a very attractive engineering problem, because of the occurrence of various types of crack initiators, such as geometrical and microstructural notches or residual M