Metallurgical study on laser-mag hybrid welding of HSLA-590 steel

Abstract

The Laser-Arc hybrid welding of HSLA-590 steel has been studied using 2.4kW CO2 laser and 350A MAG welding machine. In this paper, the leading process, MAG current, welding speeds were investigated. The results show that arc leading hybrid welding is better than laser leading hybrid welding from the result of experiments. MAG welding current of 120∼180 ampere is the effective arc parameter to get better welds in 2kW CO2 laser hybrid welding. The acceptable distance DLA between Laser and Arc is also important parameter that is decided by observing the welding process and the cross section of welds. Gap tolerance and groove angle are also investigated in the experiments.Microstructure, cooling curve of HAZ and Hardness of welds under different hybrid welding conditions were studied. The cooling curve of HAZ was measured. The cooling time (cooling from 800°C to 500°C) affects microstructure of welds and grain size in HAZ. The average grain size in HAZ was measured. The results showed the hybrid welding was u...