Microstructure characterization and mechanical properties of 2.25Cr-1Mo steel pipes using pulsed current GTAW

Abstract

The 2.25Cr-1Mo pipe was designed to withstand high pressures and temperatures in a variety of industries, including steam boiler pipes,offshore oil drilling, power generation, and petrochemicals. 2.25Cr-1Mo is a good choice for fusion welding and forming. Pulsed current GTAW providesthe advantage of joining thin sections with low heat input, leading to less deformation and warpage than TIG welding. It also allows for better weld pool management, enhanced weld penetration, and improved weld quality with less distortion and warpage. It also allows for better weld pool control, enhanced weld penetration, and improved weld quality. The goal of this research is to use a design of experiments technique to optimize process parameters and describe the microstructure and mechanical properties of 2.25Cr-1Mo pipes welded with pulsed current GTAW (DOE). The Taguchi method is used to choose the L9 (34) orthogonal array (OA) for four factors (pulse current (PC), background current (BC), pulse frequency (PF), and pulse on time (PO)) at three different levels on 2.25Cr-1Mo steel pipe joints. The pulsed current GTAW method is used to obtain the optimal combination for increased weld strength. To find the best process parameters for 2.25Cr-1Mo steel pipes, researchers used an analysis of variance (ANOVA). 220 A Pulse current, 120 A background current, 8 Hz pulse frequency, and 60 %pulse on are shown to be the best parameters for 2.25Cr-1Mo steel. Microhardness, Tensile, and Impact tests are done and compared to the parent material's properties. Some bainitic packets at the weld zone have finer lath structures, whereas others have coarser lath structures. The fracture morphology shows tear ridge, cleavage facets, and ductile dimples where failure occurs at the weld zone and it indicates ductility failure.