Abstract
This research article reports the metallurgical and mechanical properties of pulsed current gas tungsten arc welded AISI 4340 and AISI 304L by autogenous technique. This article investigates the detailed structure-property relationship of the weldments using optical and scanning electron microscopy techniques. Microstructure studies corroborated the formation of martensite at the weld zone and heat affected zone of AISI 4340, which contributed to higher hardness and strength at room temperature. Tensile studies inferred that the failure occurred at the parent metal and in the weld region when operated at ambient and high-temperature conditions (600 °C), respectively. The average tensile strength of the welded joint was found to be 708 MPa, 308 MPa in the ambient temperature and elevated temperature, respectively. Charpy V-notch studies revealed that the average impact energy of the weldments was found to be 6.2 J, due to the presence of martensitic structure at the weld. The outcomes of the study attested the use of autogenous- pulsed current gas tungsten arc welding, eliminating the need for filler wire, which is cost effective welding technique for joining these dissimilar metal combinations.

Key words
aeronautical steel, austenitic stainless steel, pulsed current, microstructure, mechanical characterization

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