Lamellar Tearing of 5083 Aluminum Alloy and Its Welds(Materials, Metallurgy, Weldability)

概要

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An investigation has been made into the lamellar tearing of 5083 aluminum alloy and its welds at-196℃ by means of fractography. This alloy has rolling texture structure and highly directional grain boundaries. For the longitudinal direction specimen, laminated fracture with many subcracks occurs. The subcracks occur along the flat grain boundary by rolling process, and the main crack is transgranular fracture independent of β phase precipitation. For the short transverse direction specimen, lamellar tearing occurs, which shows terrace and wall type's fracture. When β phase hardly precipitates, the fracture morphology shows transgranular fracture, and relatively insoluble compounds and inclusions are present at the bottom of dimple in the terrace area. When β phase precipitates at the grain boundary continuously, the fracture morphology shows intergranular fracture. In the case of non-recrystallization structure, lamellar tearing of terrace and wall type occurs in spite of intergranualr fracture. On the implant weld test of short transverse direction specimen, the fracture of welds shows lamellar tearing, which occurs in the heat affected zone so far 100μ from weld bond area. The fracture morphology shows intergranular fracture mainly, but microcracks by eutectic melting increased with increasing of weld heat input.
大阪大学の論文