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Double-sided fiber laser-arc hybrid welding was used to join 45 mm thick high strength steel over a wide range of parameters in order to investigate the efficiency of the process. Air gap size, I- and Y-groove type preparation, pulsed and cold metal transfer pulsed arc modes, arc-laser setup, and travel speeds were compared, and in all cases, sufficient filler material was provided to fully fill the gap. The welds were investigated using high speed imaging and cross-sectional analysis to identify penetration depths, morphology, and imperfections. Larger joint air gaps were found to contribute most to weld penetration depth. Surprisingly, increased line energy decreased penetration efficiency in most cases. The laser-arc interdistance was also investigated, revealing an arc size and melt flow dependency for achieving higher penetration depth for a leading arc. It was found that, although penetration can be optimized, solidification cracking can be a limiting factor in the application of deep penetration hybrid welding for thick steel section joining. [ABSTRACT FROM AUTHOR]

For many years, the oil and gas industry has utilized superduplex stainless steels due to their high strength and excellent corrosion resistance. Wire arc additive manufacturing (WAAM) was used with superduplex filler wire to create walls with different heat input. Due to the multiple heating and cooling cycles during layer deposition, brittle secondary phases may form such as intermetallic sigma (σ) phase. By inspecting deposited walls within wide range of heat inputs (0.40–0.87 kJ/mm), no intermetallic phases formed due to low inter-pass temperatures used, together with the high Ni content in the applied wire. Lower mechanical properties were observed with high heat inputs due to low ferrite volume fraction, precipitation of Cr nitrides and formation of secondary austenite. The walls showed good toughness values based on both Charpy V-notch and CTOD (crack tip opening displacement) testing. [ABSTRACT FROM AUTHOR]