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Assessment of microstructure and mechanical properties of keyhole plasma arc welded similar butt joint of AISI 304 H austenitic stainless steel

Keyhole Plasma Arc Welding (K-PAW) was employed to weld 6 mm thick SS 304 H plates. The x-ray radiography results confirmed that a sound keyhole weld was obtained for the given parameters without any defects and full penetration was achieved in a single pass. Microstructural studies revealed that weld was solidified as Ferrite—Austenite (FA) mode, and 6%–7% of delta ferrite was found in the weld. The presence of δ ferrite makes the weld least susceptible to hot cracking and sensitization. Mechanical properties tests proved that keyhole plasma weldment exhibited good strength and toughness due to the formation of finer grains and narrow heat-affected zone and meet out the minimum criteria for boiler components.