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The special designed HSLA (High Speed Low Alloy) Steel is most commonly used in Naval Steel Structures and aircraft structures due to its indigenous properties. The aim of this paper is used to investigate the effect of shielding gases in the Gas Tungsten Arc Welding process. DMR 249A [HSLA] plates were welded by GTAW by using helium and argon as shielding gas with a flow rate of 16 L/min, the interpass temperature is 140 degree Celsius and the heat input is less than 1.2KJ/min where the impact toughness, Tensile and micro hardness was studied with different shielding gas and the metallurgical properties were analysed in the base metal, heat affected zones and weld zones. A detailed study has been carried out to analyze the elements using Scanning Electron Microscopy and Energy Dispersive Spectroscopy (EDS) analysis. The properties of the high speed low alloy steel carried out reveals a better mechanical properties suitable in naval applications.

Fly ash is a light byproduct produced when pulverized coal is burnt in suspension-fueled furnaces in power plants. Separating the recovered fly ash from the exhaust gases. Due to its distinct physical and chemical properties, it is utilized in a wide variety of industrial and building applications. These applications include the production of cement and concrete, the stabilization of liquid waste, and hydraulic mining backfill. Fly ash has the potential to enhance the physical and mechanical properties of aluminum castings, as well as reduce their costs and increase their densities, all while lowering their prices. This research investigated the effect of fly ash incorporation on the mechanical properties of the aluminum casting alloy ZA8. Investigated were the cast and heat-treated varieties of unreinforced ZA8 and its metal matrix composite of 15% ferrous, 20% nickel, 10% fly ash, and 10% magnesium carbide.

Utilizing a scanning electron microscope, research was conducted on the formation of fatigue microcracks in a cast AF620 alloy. The results of fatigue microcrack propagation under escalating levels of stress indicate that the interdendritic or grain boundaries of Al grains are crucial for microcrack propagation. In Al78Zn25 regions, fatigue fractures frequently form within the grains, but if the stress concentration is high enough, they can also form at the base of the crevice on the grain boundaries. The fatigue fracture propagates in a wave-like pattern under a microscope. It was proposed that the length of the crack and the rate of formation of fatigue microcracks could be correlated to ascertain the opening displacement at the tip of the crack.

Mild steel and AISI 304 L have gained widespread usage across diverse industries, such as naval vessels, boilers, aviation, and automobile sector, due to their ready availability and distinct attributes. Fusion welding techniques have been employed to join this alloy, which is known for its specific qualities. The strength of welded joints is directly proportional to a certain percentage of the strength exhibited by the base materials. However, the welding process becomes intricate when dissimilar steels need to be joined. In such cases, achieving consistent and reliable welding become a challenge. Therefore, meticulous attention is required in the selection of electrodes, filler wires, and other operational parameters, such as current, voltage, and shielding gas. Among the solid-state joining methods, FW (Friction Welding) stands out as an excellent approach to achieving robust joints. This technique ensures strong joint formation.

Aluminum alloy AA2024 stands out as a widely utilized age-hardening alloy in aircraft applications worldwide. Despite its superior weldability in comparison to its 6000-series counterparts, AA2024 still reveals vulnerability in the welded joint. Specifically, in the T6 condition, the joint strength is only about 40% of the strength exhibited by the base metal. Faced with this challenge, design engineers often resort to selecting thicker base metal plates due to notable disparities in strength values, particularly concerning yield strength. AA2024 alloy is welded using low heat input electron beam welding. This weld is eliminated all demerits in other fusion welding process. However, heat affected zone is always a weaker region in all the fusion welding process. Post weld heat treatment process, namely, solution treatment and artificial ageing was performed to dimmish the width of weaker region.