1977 Volume 46 Issue 3 Pages 158-165
5083 aluminum alloy plate of 50 mm thickness was welded by high current MIG process. Then, Charpy impcat test was performed on base and weld metal at both room temperature and -196°C. In Charpy test, load-time curves were photographed and crack initiation energy and crack propagation energy were obtained from these curves.
Charpy impact values in the weld metal had lower values at -196°C than at room temperature and each value tended to decrease at both temperatures when a value of a parametery increased. The values ofy=0 and 100% represent the fusion boundary and center of the weld metal, respectively. Both crack initiation energy and crack propagation energy decreased also when the parametery increased.
Mg content dissolved in the weld metal which had been obtained by X-ray diffraction technique decreased when the parameter y increased. At the center of the weld metal the dissolved Mg content near the specimen surface was less than near the root of the weld metal. The change of the dissolved Mg content affected the crack initiation energy. That is, the crack initiation energy increased approximately linearly when the dissolved Mg content increased.
Fractographs fractured at room temperature showed dimple patterns. On the contrary, quasi-cleav-age like structure was mainly observed on the fracture surface tested at -196°C and many sub-cracks were also observed.