Fracture Toughness of Modern 9% Nickel Cryogenic Steels
Fracture Toughness of Modern 9% Nickel Cryogenic Steels
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断裂%20韧性%20的%20现代%209%%20镍%20低温%20钢
DOI：
10.1007/978-1-4613-9871-4_47
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
S. J. Wiersma
中科院分区：
文献类型：
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作者：
R. Stout;S. J. Wiersma
液化天然气储罐必须含有 11IK 的高度易燃气体，并具有足够的安全边际。 9% 镍钢已在 50 多个液化天然气储罐中使用十多年，从未出现过故障。气体研究所赞助了一项国际合作项目，以展示 9% Ni 钢抵抗断裂萌生和阻止扩展的能力。一个项目考虑了通过降低杂质水平来增强过去 15 年所获得的性能。统计研究表明，通过将 P 和 S 含量降低到 0.005% 以下，可大幅提高生产炉次的缺口韧性。与 ASTM 77K 下 27J 夏比冲击力的最低要求相比，在最近的生产中很容易达到超过 100J 的水平。 GRI 项目的其他阶段研究了 77K 温度下 35 至 200J 夏比炉加热 9% Ni 的止裂能力，包括焊接效果。在 40J 韧性水平下，25mm 厚的板可以阻止 100mm 长的裂纹，但在 250J 夏比韧性水平下，25mm 板可以阻止超过 750mm 长的裂纹。止裂的一个重要因素是这些相对较薄的储罐压力计的表面层吸收大量能量。虽然焊缝平面缺陷和焊缝热影响区的性能变化可能对焊接接头产生不利影响，但储罐中使用的奥氏体焊缝金属优异的断裂韧性可以补偿这些影响。
Storage tanks for liquefied natural gas must contain a highly flammable gas at 11IK with an ample margin of safety. The 9% nickel steels have served in more than 50 LNG tanks without failure for over a decade. The Gas Research Institute has sponsored an international cooperative program to demonstrate the capabilities of 9% Ni steels to resist fracture initiation and arrest propagation. One project has considered the enhancement of properties attained in the past 15 years by lowering impurity levels. A statistical study has shown the large gains in the notch toughness of production heats made by reducing P and S contents below 0.005%. In contrast to the ASTM minimum requirements of 27J Charpy at 77K, levels over 100J have readily been attained in recent production. Other phases of the GRI program have studied the crack arrest capacity of 9% Ni heats ranging from 35 to 200J Charpy at 77K, including the effects of welding. At 40J toughness level, 25mm thick plates can arrest cracks 100mm long, but at 250J Charpy, 25mm plates could arrest cracks over 750mm long. An important ingredient of crack-arrest is the large energy absorption by the surface layers of these relatively thin storage tank gages. While weld planar flaws and property alteration in the weld heat-affected zone may have adverse effects on welded joints the excellent fracture toughness of the austenitic weld metal used in tanks compensates for these effects.