Impact fracture energy of structural steel welds constructed at low ambient temperatures

• Feasibility of welding at low climatic temperatures was assessed.
• Low ambient temperature welding significantly affects the impact fracture energy of the HAZ.
• The impact fracture energy of the welds can be guaranteed for use in cold regions.

Welding at low atmospheric temperatures is frequently needed for the construction of steel structures in cold regions. In this work, the Charpy impact test in parallel with metallurgical observation was carried out to evaluate the low temperature impact fracture energy of structural steel welded joints constructed at low ambient temperatures. The impact fracture energy at low temperatures of structural steel joints welded at room temperature was also investigated for comparison. Standard V-notch Charpy impact specimens were prepared and tested under dynamic loading condition. The effects of low climatic temperatures during welding on the low temperature impact fracture energy of structural steel welded joints were explored based on the absorbed energies and the microstructures, from which the feasibility of welding in cold weather was assessed. Referring to the results, significant drop of the low temperature impact fracture energy at the heat affected zone occurs due to the rapid cooling effects. Nevertheless, it is confirmed that the impact fracture energy of structural steel welded joints constructed at low ambient temperatures can be guaranteed for use in cold regions provided that proper precautions such as the use of low-hydrogen electrodes and suitable thermal control are taken during the welding process.