Study on the R6 Selection 2 Curve for Pressure Vessel Steel in Low-Temperature Environments at Gas Field Stations

To assess the safety of pressure vessels at natural gas stations in high-altitude regions, a study was conducted to select three types of container shell materials: Q245R, Q345R, and Q370R. Tensile tests were carried out at three temperatures: 0[Formula: see text]C, [Formula: see text]C, and [Formula: see text]C. The low-temperature failure evaluation diagram was established according to the R6-Rev4 standard. The results show that, within the temperature range of 0[Formula: see text]C to [Formula: see text]C, the strength of all three materials increases as the temperature decreases, while the low-temperature plasticity remains largely unchanged and the low-temperature toughness is good. The Selection 2 curve is more representative of the material characteristics than the Selection 1 curve and tends to approach the Selection 1 curve as the temperature decreases, indicating a reduction in safety performance.