This study reports on microstructure evolution and mechanical properties of weld joints of two ASTM A335 P92 steels with varying chromium and tungsten content influenced by heat treatment. Physical simulation samples for fine-grain and intercritical heat-affected zones were done using the Gleeble® 3500 equipment. A peak temperature of 900°C (intercritical zone) and 950°C (fine-grained zone) simulated different heat-affected zones. After physical simulation, the test samples underwent two heat treatment schedules: post-weld heat treatment (PWHT) and normalisation, followed by tempering. The results show that the two steels had similar martensite microstructure. The microstructure further exhibited the presence of M23C6 carbides along the grain and lath boundaries. The P92-B steel had the highest hardness values after heat treatment except at FGHAZ + PWHT condition, which had a lower hardness value (271.9 ± 5.0 HV0.5). In this condition (FGHAZ + PWHT), P92-B steel had a higher Charpy toughness value (180J), slightly higher than the base metal (178J) due to fully formed martensite microstructure. ICHAZ + heat treatment, P92-B steel had the lowest toughness values (74J for r-PWHT and 83J for PWHT), but these values were higher than the minimum toughness value of 47J of the weld joint required for hydro-testing of the vessels. The study revealed no marked significant differences between the two steels. The heat treatment method (r-PWHT) is applicable in the industry for Type IV crack mitigation of the weld joint.

Many industries rely heavily on the availability and reliability of complex structural and functional components to execute operations efficiently. However, failure of components during service occurs due to exposure to unfavourable operating conditions, causing wear and tear of these components. The damage will result in costly downtime and potential safety hazards. Repairing, remanufacturing and refurbishing these complex parts is critical. Restoring broken structures into operation ensures the smooth operation of the industry, thus preventing losses. Conventionally, repairing parts poses a challenge. However, Wire-arc additive manufacturing (WAAM), which employs the welding principle, has revolutionised component repairing or remanufacturing. This paper reviews the literature on manufacturing complex parts, repair, remanufacture and refurbishment of broken structural and functional parts using WAAM technology. This paper also highlights the various strategies and techniques currently used to improve the quality of WAAM 3D printed parts. The study further covers the immense potential of WAAM in revolutionising the remanufacturing and repair of components. The review study has provided a roadmap for future research and development to take full advantage of this new cutting-edge manufacturing technology.

A Deform^TM-3D analysis was used to illustrate the effect of strain rate on isothermal deformation (forging) of X20CrMoV121 steel. The simulation process was conducted at an isothermal temperature of 850 °C and varying the strain rates of 1.9 s^-1, 2 s^-1 and 3 s^-1. The results of temperature, strain and stress distribution at various strain rates were reported. The strain/stress distribution exhibited a heterogeneous distribution, indicating inhomogeneity during hot forging. It was also shown that the deformation inhomogeneity decreased with the increase in the strain rate. The results are comparable to experimental publications, indicating that Deform^TM-3D is an effective tool for finite element analysis of hot deformation processes.