RESEARCH PAPER Fatigue behavior of spot-welded joints in air and under corrosive environments Part I: Materials, specimen and test results in air Dominique Thierry 1 & Flavien Vucko 1 & Gerald Luckeneder 2 & Bastien Weber 3 & Laurence Dosdat 3 & Thomas Bschorr 4 & Klemens Rother 5 Received: 18 February 2016 /Accepted: 13 June 2016 # International Institute of Welding 2016 Abstract The main aim of the project was to evaluate the influence of combined effects of fatigue loading and exposure to cyclic corrosion testing on the corrosion and the fatigue resistances of coated thin sheet steel joined by spot welding. Seven types of steel including cold rolled mild steels, high- strength steels, and press-hardened steels (PHS) were selected and provided by steel suppliers for fatigue strength evaluation of resistance spot welding (RSW) assemblies. Panels were joined using conventional resistance spot welding in both lap-shear and T-peel designs. Joined samples were painted by e-coating following the industrial process. Metallographic characterization of the steels revealed that microstructures and metallic coating composition and thickness were as expected. Cross-section of spot welds showed good quality and typical evolutions of hardness. Tensile tests performed on reference samples (non-exposed to corrosion) showed tensile which were obviously configuration and material dependent. For each configuration, three replicates were tested and did not show significant scatter. The results were and will be used to evaluate the influence of corrosion on tensile strength of the joined samples. Fatigue tests were performed Bin air^, mean- ing without corrosion exposition, leading to typical SN-lines. The results will be used to evaluate the influence of corrosion on the fatigue resistance of the joined samples. Keywords (IIW Thesaurus) Resistance spot welding . Fatigue strength . Corrosion tests . Static loading . Steels NOMENCLATURE Symbols, Abbreviations a, b Regression parameters (linear regression) BM Base material C Fatigue capacity CRS Cold rolled steel d Nugget diameter (in millimeter) ^ F Maximum force level of load range (in newton, kilonewton) ^ F ⋆ Projected load level (in newton, kilonewton) HAZ Heat-affected zone HSS High-strength steel HV0,5 Vickers hardness (Test load 4,903 N) IF Interfacial failure k Slope exponent of Basquin equation K Risk factor at confidence limit LS Lap-shear specimen N Cycles n Number of specimen in sample N avg Average cycle number for projection of fatigue capacity N f Cycles to failure PF Plug failure PHS Press-hardened steel PIF Plug interfacial failure Recommended for publication by Commission XIII - Fatigue of Welded Components and Structures * Klemens Rother klemens.rother@hm.edu 1 Institut de la Corrosion, 220 Rue Pierre Rivoalon, 29200 Brest, France 2 voestalpine Stahl GmbH, voestalpine-Straße, 4020 Linz, Austria 3 Arcelor Mittal Maizières Research SA, Voie Romaine BP 30320, 57283 Maizières-lès-Metz Cedex, France 4 GSI mbH NL SLV, Schachenmeierstraße 3, 80636 Munich, Germany 5 Munich University of Applied Sciences, Dachauerstr. 98b, 80335 Munich, Germany Weld World DOI 10.1007/s40194-016-0366-0