Study on Microstructural Characterization, Mechanical Properties and Residual Stress of GTAW Dissimilar Joints of P91 and P22 Steels

Abstract

This article deals with the dissimilar joining of two different grade Cr-Mo steel (2.25Cr-1Mo: P22 and modified 9Cr-1Mo: P91) for power plant application. The dissimilar butt-welded joint was produced for conventional V groove design by using the gas tungsten arc welding (GTAW) process with the application of an ERNiCrMo-3 Ni-based super alloy filler. A microstructure characterization was performed to measure the inhomogeneity in the microstructure and element diffusion across the interface in a welded joint. The experiments were also performed to evaluate the mechanical properties of the dissimilar welded joint in as-welded (AW) and post-weld heat treatment (PWHT) conditions. An acceptable level of the mechanical properties was obtained for the AW joint. After PWHT, a significant level of the element diffusion across the interface of the weld metal and P22 steel was observed, resulting in heterogeneity in microstructure near the interface, which was also supported by the hardness variation. Inhomogeneity in mechanical properties (impact strength and hardness) was measured across the weldments for the AW joint and was reduced after the PWHT. The tensile test results indicate an acceptable level of tensile properties for the welded joint in both AW and PWHT conditions and failure was noticed in the weak region of the P22 steel instead of the weld metal.

Numerical Simulation and Experimental Verification of Residual Stress in the Welded Joints of Weldolet–Branch Pipe Dissimilar Steels

“…Huang et al [ 21 ] used SYSWELD software to carry out numerical simulation and experimental verification of the temperature field, HAZ microstructure evolution, residual stress and post-weld deformation of S355JR-316L dissimilar metals. Sauraw et al [ 22 ] achieved the joining of P91 and P22 steels using a gas tungsten arc welding (GTAW) process, and measured the microstructural inhomogeneity and element diffusion across the interface of the welded joint. At the same time, the mechanical properties of the welded joints under as-welded and post-weld heat treatment conditions were evaluated on the basis of experiments.…”

Dissimilar Dual Phase-Low Carbon Steel Joints by the GMAW Process Subjected to Impact Load

“…Dissimilar joints are designed based on system requirements, since some irregularities can occur, such as the unmixed zone (laminar layer of base metal which has melted and resolidified in situ during the welding process) [3] between the electrode and the base materials due to the variation in chemical composition, diffusion of alloying elements that can generate an increase or loss of hardness in the interface between the bead of weld and the base material, or a non-homogeneous microstructure in the weld bead that can generate cracking due to the mixture of two different alloys. Failures could also be generated in the HAZ due to the gradient of the coefficient of thermal expansion that would increase the residual stresses at specific points [4].…”

Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation

“…Extremely attractive from the point of view of FSW industrial applications is the possibility of using the characteristic properties of various engineering materials by making dissimilar joints, especially from materials that are difficult to weld by conventional fusion welding processes [9][10][11]. For this purpose, it is necessary to overcome technological difficulties caused by significant differences between the materials to be joined in terms of structure, atomic bonds and physico-chemical properties (e.g., melting points, mechanical properties, coefficients of conductivity and thermal expansion) [12][13][14]. A particularly serious problem when joining metals is the formation of intermetallic compounds [15,16] that reduce the plastic properties of joints.…”