LNG FPSO 화물창 재료의 상온 및 극저온 기계적 성질

초록

SPB-type CCS (Cargo containment system) is taken into account appropriate for LNG FPSO. For the three materials of Al 5083-O alloy, SUS304, and 9% Ni steel, extensive tensile tests are carried out at room, intermediate low (-100˚C), and cryogenic (-163˚C) temperatures. To identify the differences of mechanical properties between base and weld parts, two types of specimens, base and weld metal specimens, are prepared. This paper suggests variation of elastic moduli, initial yield strengths based on 0.2% offset method, engineering tensile strengths, and true tensile strengths/corresponding strains. All material show a tendency to increase initial yield and tensile strengths according to the temperature decrease, meanwhile variation of elastic moduli is not as remarkable as strength variation. The largest and smallest increase ratios of the initial yield strengths according to temperature reduction are shown in SUS304 and Al 5083-O alloy, respectively. On the other hand, SUS304 and 9% Ni steels show largest and smallest increase ratios of tensile strength according to temperature reduction. Initial yield strengths of 9% Ni steels among the considered materials are the largest ones at all temperature levels, but any visible improvement of true tensile strains is not witnessed.