Mechanical properties of normal strength mild steel and high strength steel S690 in low temperature relevant to Arctic environment

• Investigate the mechanical properties of the mild steel at Arctic low temperature.
• Investigate the mechanical properties of S690 at Arctic low temperature.
• Determine the minimum cooling time for tensile tests in the cooling chambers.
• Propose formulae for mechanical properties of S690 at Arctic temperature.
• Propose formulae for mechanical properties of mild steel at Arctic temperature.

The development of Arctic oil and gas fields requires low temperature high strength steel materials that can resist critical loads in extreme environments. This paper investigates the mechanical properties such as stress–strain curves, elastic modulus, yield strength, ultimate tensile strength, and fracture strain of normal mild steel and high strength S690 steel to be used in low temperatures relevant to arctic environment. Tensile tests are carried out on steel coupons at different temperatures ranging from −80 °C to +30 °C in a cooling chamber. The influences of the low temperatures on the mechanical properties of mild steel and high strength steel are compared and their differences are discussed. Regression analyses are also carried out on the test data to develop empirical formulae to predict the elastic modulus, yield strength, and ultimate strength of the steels at ambient low temperatures. Finally, design formulae are recommended and their accuracies are further confirmed by the test data including those from the literature.