Effect of axial misalignment on the microstructure, mechanical, and corrosion properties of magnetically impelled arc butt welding joint

A GGG40 ductile iron pipe and E355+N alloy steel pipe were successfully welded using the magnetically impelled arc butt method. The influence of axial misalignment on the macroscopic morphology, microstructure, mechanical properties, and corrosion properties of welded joints was then systematically studied. The results showed that axial misalignment affected the morphology of the welded joint, causing the welded joints to become distorted, where the greater the axial misalignment, the more serious the joint distortion. The microhardness change trends of all specimens under different axial misalignments were similar. The maximum microhardness value was obtained at the center of the weld, and the maximum value was in the range of 354.2 and 387.1 HV. The presence of axial misalignment caused significant changes in the tensile properties of the specimen. As the axial misalignment increased, the ultimate tensile strength gradually decreased. When the axial misalignment was between 0 and 1 mm, the ultimate tensile strength of the specimen decreased slightly. When the axial misalignment reached 2.5 mm, the ultimate tensile strength dropped about 219 %. With slight axial misalignment, the specimen underwent ductile fracture in the ductile iron pipe base metal area. By contrast, when the axial misalignment reached 2.5 mm, brittle fracture occurred in the weld seam area. The corrosion performance of the specimens varied less under different axial misalignments. The corrosion potential was between 883.35 and 908.61 mv, and the corrosion current density reached 2.52–3.28 μA/cm2, and the corrosion performance was between two base metals. [Display omitted]