Properties Of Dissimilar Welded Joints Research Articles

Microstructure and Mechanical Properties of Dissimilar Ferritic and Austenitic Steel Joints with an Intermediate Inconel-182 Buttering Layer

In this study, microstructure and mechanical properties of dissimilar weld joints between 2.25Cr-1Mo ferritic steel and 316L austenitic stainless steel, with and without an Inconel-182 buttering layer, have been investigated. The buttering layer widths produced on the machined edges of the ferritic steel plate were 3 and 5 mm. The dissimilar weld joints were butt-welded using a SMAW process with Inconel-182 electrodes. The results indicate that the ferritic base metal dilution effects are minimized due to buttering and a more uniform distribution of Fe, Ni, Cr and Nb contents is established over a broad region within the fusion zone. Moreover, a microstructure consisting of combined columnar and equiaxed dendrite with interdendritic Nb-rich particles is developed within the fusion zone as a result of buttering. Mechanical tests show that the average hardness, tensile ductility and impact energy of the weld metal were enhanced with increasing width of the buttering, while tensile strength properties were unaffected. It is observed that fracture surfaces of tensile specimens exhibit ductile features composed of ductile tear ridges with numerous interspersed dimples. However, the dominant fracture mode is noted to change from interdendritic to transdendritic with the use of a buttering layer.

５０５２／２０１７アルミニウム合金摩擦圧接継手接合界面の機械的混合層と機械的性質

The mechanically mixed layer at a weld interface and the mechanical properties of dissimilar welded joints of 5052 aluminum alloy to 2017 aluminum alloy, which were made by using a brake type friction welding machine were examined with different welding conditions. The mechanically mixed layer is formed on the friction process, and it is observed at a weld interface all over. The thickness of the mechanically mixed layer decreased with increasing friction pressure, the mixed layer of the outside of joint became thinner than that at the center. The tensile strength of joints which were made with the friction pressure of above 45 MPa, which had an average thickness of 200 μm in mechanically mixed layer, showed 85% of 5052 aluminum alloy base metal. The breakage occurred at the softened area of 5052 aluminum alloy side. The impact strength of joints, which had an average thickness of 200 μm in mechanically mixed layer, were 70% of 5052 aluminum alloy base metal.