Comparative study between TIG-MIG hybrid and MIG welding of 1.4462 duplex steel joints

Abstract Duplex steels are used for applications that require high strength and ductility combined with good corrosion resistance. An economical welding technology to handle these steels is achieved by combining a MIG and TIG arc process. The aim is to improve welding speed and quality by utilizing a TIG-MIG hybrid welding process to join 1.4462 duplex steel with a thickness of 2 mm. The interaction between the two arcs, caused by the blowing effect, is an enormous challenge, that can be counteracted with a defined torch position and current modulation. For this purpose, a variation of the MIG (pulsed and AC pulsed arc) and TIG process (AC and pulsed DC) took place. The influence of electrical parameters on process stability and material transfer were investigated. For analysis, an evaluation of high-speed recordings (5,000 frames per second) and synchronized measured current / voltage curves (200 kHz) is carried out. Based on a number of selected specimens, a welding procedure test according to ISO 15614-1 are performed to determine the welding seam quality. The test includes the characterization by tensile and hardness testing, macroscopic and microscopic examination. Additionally, the specimens are examined according to ISO 5817.