An experimental study on mechanical, fatigue and crack propagation properties of IMO type B CCS materials at room and cryogenic temperatures

초록

IMO type B CCS (cargo containment system) is considered for LNG FPSOs. For the three materials of SUS304, 9% Ni steel and Al 5083-O alloy, regarded as possible candidates for IMO type B CCS, extensive tensile, fatigue, fatigue crack growth rate and CTOD tests were carried out at room, intermediate low (-100°C) and cryogenic (-163°C) temperatures in this paper. All materials show a tendency for initial yield and tensile strengths to increase with decrease in the temperature, while change in elastic moduli is not as remarkable. The largest and smallest increase ratios of the initial yield strengths due to temperature reduction are seen in SUS304 and Al 5083-O alloy, respectively. In fatigue tests, fatigue strengths increase due to the temperature decrease for three materials. The highest increase of fatigue strength due to the temperature decrease is observed in Al 5083-O alloy, while 9% Ni steel shows lowest increase. In fatigue crack growth rate test, SUS304 and Al 5083-O alloy show reduction in crack propagation rate, due to the reduction in temperature, while any visible improvement of da/dN is not witnessed in case of 9% Ni steel. In CTOD test, CTODs tend to decrease in case of SUS304 and CTODs for Al 5083-O alloy increase with reduction in temperature. © 2011 Taylor & Francis Group, London.