Hydrogen charged effects on mechanical properties of 5083 aluminum alloy and its weld metals - (Study on low temperature materials used in WE-NET 12)

The "WE-NET: World Energy Network' project aims to solve global environmental problem to consider clean energy with hydrogen conversion. Since liquid hydrogen has been expected to be an effective energy carrier and clean energy resource in their future use. The project tries to establish the following subjects: 1) developing cryogenic materials that are used in storage tanks and transportation vessels for liquid hydrogen, 2) determining their necessary requirements from materials to design both the tanks and the vessels. Aluminum alloy A5083 is one of possible candidate materials for the liquid hydrogen storage. Since there are a lot of applications of 5083 for Liquid Natural Gas (LNG) storage, such as LNG tanks and LNG ship carriers. We report hydrogen charged effects on mechanical properties of 5083 aluminum alloy and its weld metals. Firstly, the hydrogen content in the 5083 base metal increases from 0.11 ppm to 1.1 ppm after hydrogen charge such as 9.8 MPa, 623K, 79 h. Therefore, there is little effect on hydrogen absorption in the base metal. Secondly, in mechanical properties, although we have found tensile strength and elongation of the welded joint and the weld metal decreased at 4K with hydrogen charge due to heat treatment we can not find any significant effects of hydrogen charge on tensile test and Charpy impact test. We discuss those properties in terms of practical conditions on liquid hydrogen storage.