An experimental investigation into the mechanical properties of austenitic A4‐70 (EN 1.4401) and duplex DX109 (EN 1.4462) stainless steel bolts at elevated temperatures is presented. A total of 52 tensile coupon tests were conducted, comprising 24 steady-state (isothermal) tests at temperatures ranging from 25 °C to 1000 °C, and 28 transient-state (anisothermal) tests at stress levels spanning 0%–80% of the ultimate tensile strength at room temperature. The key temperature-dependent material properties were derived from the steady-state and transient-state tests and compared with the design values specified in EN 1993‐1‐2 and the existing test data in the literature. The test results indicate that the current design values for the 0.2% proof strength, the strength at 2% total strain and the ultimate tensile strength are somewhat unconservative for A4‐70 stainless steel at temperatures above 700 °C, primarily due to the loss of the benefit of cold work. The EN 1993‐1‐2 strength reduction factors are generally conservative for DX109 stainless steel across the full temperature range. Based on these findings, two sets of grade-specific material property reduction factors are proposed for A4‐70 and DX109 stainless steel bolt grades. The two-stage Ramberg-Osgood model included in EN 1993‐1‐2 is shown to accurately capture the stress-strain behaviour of both bolt grades at room and elevated temperatures.
Zhang et al. (Fri,) studied this question.