Abstract
AbstractShips and offshore structures may be operated in areas with seasonal freezing temperatures and extreme environmental conditions. While current standards state that attention should be given to the validity of fatigue design curves at subzero temperatures, studies on fatigue strength of structural steel at subzero temperatures are scarce. This study addresses the issue by analysing the fatigue strength of welded steel joints under subzero temperatures. Although critical weld details in large welded structures are mostly fillet‐welded joints, most published data are based on fatigue crack growth rate specimens cut out of butt‐welded joints. This study analyses fillet‐welded specimens at −20°C and −50°C against controls at room temperature. Significantly higher fatigue strength was measured in comparison to estimates based on international standards and data from design codes even at temperatures far below the allowed service temperature based on fracture toughness results.
Highlights
Due to the large unexploited oil and gas reservoirs in Arctic regions, there has been a significant increase in ship traffic in Arctic regions; oil rigs and wind turbines have been increasingly set up in areas with seasonal freezing temperatures
It should be remarked that the fatigue strength for a probability of survival Ps = 97.7% at N = 2 · 106 of the S235 transverse stiffener lies below the reference fatigue strength of FAT80 due to the relatively high scatter of this test series
The fatigue strength of the S500 cruciform joints is lower than the corresponding S235 weld detail; this might be related to the more convex fillet weld shape of the S500 cruciform joints, which can be seen from the macrographs
Summary
Due to the large unexploited oil and gas reservoirs in Arctic regions, there has been a significant increase in ship traffic in Arctic regions; oil rigs and wind turbines have been increasingly set up in areas with seasonal freezing temperatures. These structures, and their materials, must be designed to meet these environmental conditions. It is known that lower temperatures change the material properties of steel and their welded joints, the resulting effects are poorly understood so far; this is especially true for fatigue behaviour at subzero temperatures.[1]. Data for structural steels subjected to temperatures relevant for Arctic conditions are especially scarce and—except for Bridges et al[3] and Li et al,[8] who tested longitudinal stiffeners and cruciform joints, respectively—all mentioned studies are based on tests with butt‐welded joints
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