Triple-Wire High Speed GMAW Butt Joint Welding Process Of Marine E Grade Steel

Shipbuilding industry is a strategic industry, which provides major equipments to national defense, marine exploitation. And welding technology is one of the key technologies about shipbuilding. High-speed, high-efficient multi-wire welding is current domestic and international research focus. This paper launched the influence of multi-wire GMAW to marine grade E steel welded joint performance and quality. And this research can provide technical support of high-efficient, high-quality multi-wire welding to ship-build enterprises.This paper built the three-wire butt welding test platform. Studied the single-/twin-/triple-wire welding process, and the microstructure . Besides, basing on tensile strength of welded joints, hardness measurement and -40℃V-notch impact test , the paper studied the relationship between microstructure and mechanical properties of welding joints .The results showed that: (1) About build-up welding, the single-/twin-/triple-wire welding efficiency ratio approximately meet 1:2:3. The microstructure of triple-wire welding is similar to single/ twin-wire welding. In addition, when the linear energy of triple-wire welding are 42500J/cm,34000J/cm,28333J/cm, the hardness and microstructure did not change significantly. (2) Get the fine butt welding parameters. The single-/twin-/triple-wire welding efficiency ratio approximately meet 2:5:8. (3) The microstructure of triple-wire welding is: pro-eutectoid ferrite +P+ granular bainite + acicular ferrite in weld seam; P+F in fine grain zone and coarse grain zone; block F and small P in two-phase region.(4) The tensile strength of triple-wire welding was 560MPa, and the fracture occurred at the base metal; the impact toughness was 44J at -40℃; Impact fracture morphology mainly quasi-cleavage fracture, and contained a small amount cleavage and dimple fracture. These mechanical meet the welding procedure qualification standards (NB/T 47014-2011).