Solid State Diffusion Bonding Using Superplasticity of δ/γ Duplex Stainless Steels

概要

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Solid state diffusion bonding of superplastic ferrite/austenite duplex stainless steels with similar and dissimilar ferrous alloys has been studied by means of hot compressive testing at temperatures ranging from 1075 to 1575 K in a nitrogen atmosphere. By using the superplasticity of duplex stainless steels, a good bonding, in which the specimen is fractured in the base metal by room temperature tensile testing, can be obtained in a significantly short time, e.g., the critical time for the bonding at 1373 K under a pressure of 19.6 MPa was 120s in the case of similar bonding of as-hot rolled 25%Cr-7%Ni-3% Mo duplex stainless steels. In the vicinity of the bonding interface, a fine microstructure is observed, indicating dynamic recrystallization due to superplastic deformation. The weldability is hardly deteriorated by increasing the surface roughness up to 100μm or by mixing O_2 up to 0.5% in the N_2 atmosphere, because of easy adhesion or easy breakage of the oxide film formed on the bonding interface. Bonding of the duplex stainless steels with other non-superplastic alloys such as austenitic, ferritic stainless and low carbon steels can also be obtained. By using the superplastic duplex stainless steel sheets as insert materials, non-superplastic steels can easily be joined. The critical bonding time depends largely on the superplasticity of the insert materials.
社団法人溶接学会の論文
1988-10-01