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Abstract
Maraging steel 250 grade plates of 10 mm thickness were welded in single pass using a laser-arc hybrid welding (LHW) setup comprising 3.5 kW CO2 laser and synergic pulse metal inert gas (MIG) welding power source at a welding speed of 1 m/min. The influence of single-pass welding on the bead characteristics, microstructure, and mechanical properties was investigated. The size and volume fraction of reverted austenite was effectively reduced in the fusion zone. Moreover, the width of the heat-affected zones (HAZ) was reduced and the microhardness results did not show significant softening in the HAZ after post weld aging. Tensile testing of the welds in transverse direction showed 97.3% weld efficiency. The fusion zone exhibited KIc fracture toughness of 77.4 MPa√m which was affected by the distribution pattern of reverted austenite. The study vividly brings out the process advantages of LHW for accomplishing thick section welds of maraging steel in single pass with narrow groove and lesser filler wire consumption.
ACKNOWLEDGMENTS
The authors are thankful to Mr E. Anbu Rasu, ARCI for his assistance in carrying out the laser hybrid welding experiments and mechanical testing. Thanks to Dr Gururaj Telasang, ARCI, for his valuable inputs and support in characterization. Dr Suresh Babu, ARCI, Mr M. Govindaraju, NFTDC, Hyderabad and colleagues in AMTL, Hyderabad are acknowledged for their help in carrying out tensile tests and fracture toughness tests. Thanks to Dr. Ravi Bathe, ARCI, for his help during various stages of manuscript preparation. The authors also thank Mr. G. V. R. Reddy, ARCI, for his help with scanning electron microscopy.