Ab initio calculation study on the site of hydrogen in Al–Zn–Mg alloys was performed to clarify the mechanism of hydrogen segregation, aiming to understand the mechanism for hydrogen embrittlement in Al–Zn–Mg alloys. In order to determine stable structures with hydrogen at grain boundaries as well as inside the grain, atomistic models of Al matrix, Al/Al and Al/MgZn₂ boundaries containing a hydrogen atom were constructed, and their total energies as well as stable structures were calculated by the ab initio method. We defined and estimated the formation energy of hydrogen and compared the stability of segregated hydrogen in Al matrix, Al/Al and Al/MgZn₂ boundaries. We found that hydrogen has a tendency to segregate in Al/MgZn₂ boundaries, η1, η4, η2 (notation used by J. Gjønnes and Chr. J. Simensen) in this order. This is in accord with the thought that hydrogen is prone to be trapped on a semicoherent boundary, which was previously concluded from experimental results.

The thickness of the product to be formed by the shear spinning of sheet metal is governed by the sine law, which means plane strain mode. Since the thickness of the walls which is formed by this process becomes zero theoretically, it is not possible to produce a cylindrical shape. On the other hand, the die-less shear spinning technology using an elastomer of general-purpose, has been developed recently. The bar tool with hemispherical tip is used on this process. The blank sheet is mounted on the elastomer at first, and they are rotated on the spinning lathe. In accordance with the NC program, the bar tool, while pushing the tip for the elastomer surface to an effectual depth, and is driven to squeeze the flat surface around the product. The strain generated by this operation is independent from the sine law. It means that it is possible to manufacture a cylindrical shape, despite this process is the shear spinning type. Some of forming experiments have been carried out to make a product with cylindrical shape using aluminum alloy sheet 5052. As a result, the cylindrical shape of three times or more the height of the diameter was made successfully.

The experiments such as corrosion mass loss and polarization curve test have been carried out to obtain corrosion behavior of Ti in a mixture of 10 mass% hydrogen peroxide and 10 mass% ammonia solutions. The polarization resistance curve by differentiating the experimental polarization curve told us that the corrosion system has shown the fast reaction properties and its corrosion rate was largely influenced by existence of oxide film on the titanium. It was found that an estimation of corrosion rate using the characteristics on the polarization resistance curve is in good agreement with that of the corrosion mass loss measurement.