Behavior of High Strength Steel Butt Joints at Arctic Low Temperatures

To study the effect of Arctic low temperatures on the behavior of HG785 high strength steel butt joints, the microstructure observation, hardness distribution tests, and uniaxial tensile tests were performed on the butt joints fabricated by using two types of weld metals with exposure to five ambient and low temperatures. The results show that the butt joints possess a coherent metallographic structure and exhibit good fusion between weld metal and base metal. Only a softening heat affected zone is observed in the weld joint samples under two matching conditions. The butt joint tensile specimens exposed to Arctic low temperatures possess higher strengths compared to those at ambient temperatures. The ductility improvement due to low-temperature exposure for equal-matching welded butt joint is substantial, whilst that for over-matching welded butt joints is negligible. All butt joint tensile specimens fail in a ductile manner. The findings provide a scientific basis for the engineering applications of high strength steel structures in Arctic low-temperature regions.