Sallaba, FinnFinnSallabaRolof, FranziskaFranziskaRolofEhlers, SörenSörenEhlersWalters, Carey LeroyCarey LeroyWaltersBraun, MoritzMoritzBraun2022-02-252022-02-252022-02-23Metals 12 (3): 385 (2022)http://hdl.handle.net/11420/11767The formation and propagation of cracks occur through irreversible dislocation movements at notches, material defects, and grain boundaries. Since this process is partly thermally controlled, the resistance to dislocation movements at low temperatures increases. This slows both fatigue initiation and fatigue crack propagation. From recent experimental data, it can be seen that fatigue crack growth is accelerated below the fatigue transition temperature (FTT) that correlates with the ductile-brittle transition temperature (DBTT) found by well-known fracture mechanics tests, i.e., Charpy impact, fracture toughness, and CTOD. Hence, this study investigates the relation between FTT and DBTT in S500 high-strength steel base material and welded joints at low temperatures using fatigue crack growth, fracture toughness tests as well as scanning electron microscopy. From the tests, an almost constant decrease in fatigue crack propagation rate is determined with decreasing test temperature even below the DBTT. At −100 °C, the fatigue crack propagation rate is about half of the rate observed at room temperature for both base material and weld metal.The formation and propagation of cracks occur through irreversible dislocation movements at notches, material defects, and grain boundaries. Since this process is partly thermally controlled, the resistance to dislocation movements at low temperatures increases. This slows both fatigue initiation and fatigue crack propagation. From recent experimental data, it can be seen that fatigue crack growth is accelerated below the fatigue transition temperature (FTT) that correlates with the ductile-brittle transition temperature (DBTT) found by well-known fracture mechanics tests, i.e., Charpy impact, fracture toughness, and CTOD. Hence, this study investigates the relation between FTT and DBTT in S500 high-strength steel base material and welded joints at low temperatures using fatigue crack growth, fracture toughness tests as well as scanning electron microscopy. From the tests, an almost constant decrease in fatigue crack propagation rate is determined with decreasing test temperature even below the DBTT. At −100 °C, the fatigue crack propagation rate is about half of the rate observed at room temperature for both base material and weld metal.en2075-470120223Multidisciplinary Digital Publishing Institutehttps://creativecommons.org/licenses/by/4.0/arctic conditionsweldment fatiguetemperature dependence of material fatiguefatigue and fracture mechanics testing at low temperaturesfatigue and fracture transitions temperaturesdirect-current potential drop methodscanning electron microscopyfracture toughness testingstructural steelTechnikIngenieurwissenschaftenJournal Article2022-02-2410.15480/882.419010.3390/met1203038510.15480/882.4190Lee, Jae MyungJae MyungLeeJournal Article