Study Of Dynamic Fracture Toughness And Structure Of 10Ni5CrMoV Steel MIG Horizontal Position Welding Joint

10Ni5CrMoV steel is an important ship building steel made in china. The MIG horizontal position welding applied to 10Ni5CrMoV steel is a new process that some shipyard is researching. Study of dynamic fracture toughness and structure of 10Ni5CrMoV steel MIG horizontal position welding joint is a significant work for judging its mechanical properties and advancing welding process.In this paper the Charpy impact energy and the dynamic tear (DT) energy of welding metal, fusion line and 2mm from fusion line was measured in different temperature. The microstructure and fine structure was investigated. The fracture appearance of Charpy impact specimens and DT specimens was investigated. The elements of oxides in weld metal and fusion line is analyzed with EDS. The macrostructure of welding joint was investigated. The hardness distribution of welding joint was measured.The result shows: dynamic fracture toughness of 10Ni5CrMoV steel MIG horizontal position welding joint is excellent. The oxides in weld metal and fusion line are the particles that will cause nucleation of acicular ferrite to occur and a lot of acicular ferrite in weld metal and fusion line should be one of the important reason of a excellent low temperature dynamic fracture toughness of weld metal and fusion line.