The Research Of Marine Engineering EQ56?EQ70 SAW And Laser Welding With Filler Wire Procedure

In accordance with marine engineering EQ56,EQ70 steel alloy composition and its performance requirements,we have used three kinds of welding wire and flux produced by ESAB?Oerlikon?Atlantic company respectively,to do welding material deposited metal welding test and compare their mechanical properties,and also have done three kinds of submerged arc welding process respectively.We also have analyzed and compared the influence on the microstructure and mechanical properties of different welding materials in the same heat input conditions,and the influence on microstructure and mechanical properties of different heat input in the same welding materials.Meanwhile,we also have done the research in EQ70 steel narrow gap welding process by laser welding with filler wire,to observe and analyze the microstructure of the EQ70 welded joints,and test its mechanical properties,and also the its welding two different methods were compared.Comparison and analysis of the results showed that for EQ56,EQ70 steel,the welding materials of three kinds of the deposited metal could have good mechanical properties.EQ56 steel submerged arc welding using ESAB OK Flux 10.62 OK Autrod 13.40 flux matching wire,welding voltage between 30 V,welding current is 640 A,layer at a temperature of 160 ? welding process conditions,showed that it could have excellent performance,The columnar crystals of ferrite of grain boundaries has small and narrow width,there is a large number of fine acicular ferrite,but no side bar ferrite appears.Tensile strength is 726 MPa,under the conditions of-40 ? impact energy weld center is 117 J,the impact energy of the fusion line is 59 J,fusion line + 2mm impact energy is 62 J,fusion line + 5mm impact energy is 64 J.EQ70 steel submerged arc flux using ESAB OK Flux 10.62 with OKTubrod15.27 S type wire,under the welding voltage between 35 V,welding current is 680 A,layer temperature 170 ? welding process showed that the welding joints contain a large number of acicular ferrite,a small amount of granular bainite,a handful of non-carbon bainitic,the performance was best.Tensile strength is 837 Mpa,under the conditions of-40 ? impact energy weld center is 91 J,the impact energy of the fusion line is 50 J,fusion line + 2mm impact energy is 62 J,fusion line + 5mm of impact energy is 170 J.At the same welding materials,with heat input from 30KJ/cm increased to 40KJ/cm,EQ56,EQ70 tensile steel welded joints have declined,so did the low temperature impact toughness.The HAZ area appears inevitable softening problem,we must limit the heat input strictly.For EQ70 steel,using CARBOFIL FK 800 narrow gap laser welding with filler wire,those forming of one-side welding is excellent and symmetrical,the amount of deformation is small.The HAZ is very narrow,only about 2mm.The welded joint was not found that the sidewall had no fusion,cold cracks and other defects.The strength of welded joint is high,but the impact toughness of welded joints is only 45 J.the-40 ? impact energy of fusion line + 1mm area is low,only 50 J.From the overall distribution,the regional steel hardness of EQ70 SAW joints are generally lower than the hardness of the narrow gap filler laser welding with wire,however,the average impact energy of the HAZ by SAW is higher than that of the joints' HAZ by narrow gap laser welding with filler wire.