Mechanical and microstructural properties of SMAW and GMAW welded joints of HY-80 steel

The welding of high strength steels represents a continuous challenge taking into account the great variety of alloys systems, which present stringent requirements of high strength and toughness. Into this context the HY-80 steels largely employed in the Naval Industry are still welded preferentially by the SMAW process, despite its limitations when compared with other welding processes. In order to promote an improvement on productivity, the present work presents a comparative analysis between the mechanical properties of the HY-80 welded joints performed by the GMAW and SMAW processes. Multipass welding by shielded metal (SMAW) arc and gas metal arc welding (GMAW) processes were performed with preheating and inter-pass temperatures of 90 degrees C and 150 degrees C respectively in plates of dimensions 850X150X30 mm in HY-80 steel, in the flat position and average energy welding of 1.29 for SMAW and 1.36kJ/mm for GMAW process. After welding a post weld heat treatment at 600 degrees C for 1 hour was performed, this condition being compared with the as welded condition. Tensile, Charpy-V notch and hardness tests and metallographic examination by scanning electron microscopy were performed for mechanical and microstructural characterization. Additionally, it was carried out a comparative analysis between processes. The results show that it is possible to achieve adequate mechanical properties for all analyzed conditions. Furthermore, it was observed that the productivity provided by the gas metal arc welding process was greater than shield metal arc welding.