Low-Temperature Tensile Strength of J55 and P110 Tubular Steels and an Elastic Consistency Check of a Scaled Tubular Model

This study reports the tensile strengths of J55 and P110 tubular steels at low temperatures and assesses the consistency of the geometry, loading, and material inputs in an existing single-tube Abaqus/Explicit model. Ten tensile tests were conducted at five chamber temperatures from −60 to 20 °C, with one specimen per grade–temperature condition. Force and extensometer measurements were recorded at a crosshead speed of 3 mm/min after at least 30 min of thermal conditioning. Between 20 and −60 °C, J55 yield strength increased from 403 to 436 MPa (8.2%) and ultimate tensile strength from 609 to 718 MPa (17.9%). The corresponding P110 values increased from 876 to 952 MPa (8.7%) and from 984 to 1057 MPa (7.4%). For the documented 1000 mm model, a 120 kN axial force gives an analytical nominal stress of approximately 551 MPa and an elastic elongation of 2.71 mm. The model contains a single set of temperature-dependent plasticity inputs obtained by processing experimental curves for both steels. This combined set does not provide separate constitutive descriptions of J55 and P110. Its initial plastic stresses are all above 551 MPa, so the nominal calculation assesses elastic consistency only. The results document the measured strength changes and the scope of the existing model; independent validation is still required for grade-specific plastic deformation and fracture predictions.