Hybrid Laser-GMA Welding of High-Strength Steel Grades

Abstract

Abstract The results of investigations on hybrid laser + gas metal arc (GMA) welding of butt joints of different fine-grained and thermomechanically rolled steel plates 5.0 mm thick are presented in the article. The hybrid welding tests were carried out on steel grade Domex 700MC, Domex 960, and Domex 1100. The experimental stand for hybrid welding consisted of the laser welding head and also the arc GMA torch. Butt joints of Domex 700MC plates were hybrid welded applying a metal cored wire Stein Megafil 742B (Charpy V: 80 J at −20°C). In turn, the butt joints of Domex 960, and Domex 1100 steel plates were hybrid welded applying a metal cored wire Stein Megafil 1100M (Charpy V: 55 J at −20°C). The quality of the test joints was analyzed by means of visual inspection and cross-section observation. In turn, the mechanical properties were evaluated by means of a static tensile test of the welded joints and also impact toughness of the weld metal. The results showed that the hybrid welding can provide a proper shape of weld even at altering gap between the butt surfaces of the groove and also at distinct shift of the electric arc to the laser beam spot. Results of tensile tests showed that the hybrid welded joints of Domex 960 and 1100 have the strength at similar levels of approximately 1,140 MPa, which is significantly higher compared to the joints of Domex 700MC at approximately 820 MPa. In turn, the weld metal of the Domex 700MC steel exhibited the highest impact toughness at a mean value of 139 J/cm2, whereas the test joints of Domex 960 showed lower impact toughness at approximately 122 J/cm2. Surprisingly, the lowest impact toughness was determined for the joints of Domex 1100, despite the same wire being applied for the Domex 960.