Low Temperature Effects on the Fracture Behavior of Cold-Worked STS 304 Stainless Steel for Membrane of LNG Storage Tank

The temperature dependence of the tensile properties and the fracture toughness of the cold-worked STS 304 stainless steel have been examined in the temperature range of 293 K to 111 K. The tensile strength significantly increases with a decrease in temperature, but the 0.2% yield strength is relatively insensitive to temperature. The total elongation at 193 K abruptly decreases by 50% of that at 293 K, and it decreases slightly at 193 K to 111 K. The strain hardening exponents at low temperatures are about four times as high as that at 293K. Initiation fracture toughness (Jc) and tearing modulus (Tmat) tend to decrease with a decrease in temperature. The Jc values exhibit an inverse dependency on the effective yield strength (σflow) at all the test temperatures. Fractographic examination revealed that the critical stretch zone width (SZWc) at room temperature was about three times as large as that at 111 K. This indicates that the variation in fracture toughness according to temperature corresponds to the decrease in SZWc with decreasing temperature.