Microstructure and properties of laser hybrid welding joint of AH36 marine steel

Abstract

Abstract AH36 Marine steel 10mm thick was welded by Laser-MIG hybrid welding process, and the structure and properties of the arc zone and laser zone of the Laser-MIG hybrid welding joint were studied respectively. The results show that the width of welding seam and HAZ in arc action zone is obviously larger than that in laser action zone. The microstructure of the weld was mainly acicular ferrite, bainite, martensite and grain boundary ferrite, and the content of martensite and bainite in the laser action area was relatively higher. The microstructure of the coarse grain zone is mainly thick lath martensite, granular bainite and acicular ferrite, and the microstructure of the arc action zone is relatively larger. The microstructure of the fine crystal region is mainly fine ferrite and pearlite. The hardness of arc zone and laser zone is distributed symmetrically in the weld center, the lowest hardness occurs in the weld center, and the high hardness occurs in the weld HAZ. The tensile specimens in the arc zone were fractured near the HAZ and the laser zone was fractured on the base metal far away from the weld. The lowest value of impact absorption work at 0°C in arc action area and laser action area appeared at the fusion line +0.5; the highest value of impact absorption work at 0°C in arc action area appeared at the fusion line +1.0, the fusion line +1.5, and the fusion line +2.0; the highest value of impact absorption work at 0°C in laser action area appeared at the fusion line. The impact absorption at 0°C in the laser action area is higher than that in the arc action area.