A high pressure material testing system (max. pressure: 140 MPa, temperature range: −80 ∼ 90 °C) was developed to investigate the testing method of material compatibility for high pressure gaseous hydrogen. In this study, SSRT and fatigue life test of JIS SUS304 and SUS316 austenitic stainless steel were performed in high pressure gaseous hydrogen at room temperature, −45, and −80 °C. These testing results were compared with those in laboratory air atmosphere at the same test temperature range. The SSRT tests were performed at a strain rate of 5 × 10−5 s−1 in 105 MPa hydrogen gas, and nominal stress-strain curves were obtained. The 0.2% offset yield strength (Ys) did not show remarkable difference between in hydrogen gas and in laboratory air atmosphere for SUS304 and SUS316. Total elongation after fracture (El) in hydrogen gas at −45 and −80 °C were approximately 15 % for SUS304 and 20% for SUS316. In the case of fatigue life tests, a smooth surface round bar test specimen with a diameter of 7 mm was used at a frequency of 1, 0.1, and 0.01 Hz under stress rate of R = −1 (tension-compression) in 100 MPa hydrogen gas. It can be seen that the fatigue life test results of SUS304 and SUS316 showed same tendency. The fatigue limit at room temperature in 100 MPa hydrogen gas was comparable with that in laboratory air. The room temperature fatigue life in high pressure hydrogen gas appeared to be the more severe condition compared to the fatigue life at low temperature. The normalized stress amplitude (σa / Ts) at the fatigue limit was 0.37 to 0.39 for SUS304 and SUS316 austenitic stainless steels, respectively.
PARAMETRIC OPTIMISATION OF PULSED – TIG WELDING PROCESS IN BUTT JOINING OF 304L AUSTENITIC STAINLESS STEEL SHEETS
