Joints Characteristics of Dissimilar Materials Friction Welds (I) : Titanium/AISI 304L Stainless Steel(Mechanics, Strength & Structure Design)

概要

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The inadequate bend ductility of joints results from the combined effects of (FeNiCr)Ti intermetallic phase formation at the joint interface and the development of a locally-hardened region in titanium material immediately adjacent to the bondline. The poor bend testing properties of dissimilar joints are not associated with the residual stress generated during cooling. The plastic strain distribution in dissimilar joints corresponds well with the hardness distribution in as-welded joints. Removal of the locally-hardened region in the titanium substrate via post-weld-heat-treatment markedly improves bend ductility and only marginally decreases tensile strength. The optimum mechanical properties are produced in joints post-weld-heat-treated at 500℃ for one hour. Longer holding times at 500℃ promote the formation of a thick intermetallic layer at the joint interface. When this occurs, fracture during tensile testing shifts from the titanium base material to the joint interface. Provided that development of a locally-hardened region in the titanium substrate is counteracted without the formation of a thick intermetallic layer at the joint interface, friction joining can produce dissimilar titanium/AISI 304L stainless steel joints with satisfactory mechanical properties.
大阪大学の論文