深海潜水調査船耐圧殼用高靭性高張力鋼の溶接に関する研究(第 1 報)

概要

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For prcssure hulls of Deep Submergence Vehicle (DSV) operating in seas of 2000m depth, the most important point is the maximum load carrying capacity under the minimum weight. For this reason, spherical shell made of high strength steel is adopted for pressure hulls. Spherical shape is an optimum shape for external hydrostatic pressure loading and the most suitable steel for this shape is HT100 steel (5 Ni-Cr-Mo-V quenched and tempered steel with a yield strength of 90kgf/(mm)^2). However, in the application of HT100 steel to spherical pressure hulls, there are some difficult problems from the view point of fabrication; that is, (1) quenching and tempering procedure of hemisphere. (2) welding procedure of two hemispheres and penetrate joints. Then heat treatment conditions and TIG welding conditions were investigated. The results obtained are summarized as follows : (1) The quenching cooling rate of HT100 is needed over 3℃/sec for satisfying required property. (2) The mean quenching cooling rates of hemisphere (thickness : 60mm, diameter 2320mm) are 5.7∿6.2℃/sec. Then it is possible to fabricate hemisphere by hot forming method. (3) It is necessary to preheat over 100℃ for preventing cold crack. (4) The cooling rate (at 540℃) of weld metal is required over 20.5℃/sec for guarantee 90kgf/(mm)^2 proof stress.
社団法人溶接学会の論文
1981-02-05