Q490SD型钢焊接接头不同埋弧焊工艺微剪试验OA

Double-wire submerged arc welding has the advantages of high welding efficiency and good weld quality,and is widely used in the manufacturing of pressure structures in large hydropower stations.This paper uses micro-shear tests to study the shear strength and indentation rate of Q490SD steel double-wire submerged arc welded joints under different weld-ing speeds(55 cm/min,60 cm/min,65 cm/min,70 cm/min).Results show that the welded joints of double-wire submerged arc welding have the same plasticity and higher shear strength as those of single-wire submerged arc welding.When the line energy of double-wire submerged arc welding is controlled between 28 and 40 kJ/cm,the quality of the welded joints can meet the standard requirements.Moreover,as the welding speed increases,the grain size in the coarse-grained zone is re-fined from 80.0 μm to 47.6 μm,and the grain size is improved from 4.0 to 5.5.The refinement of grain size and the improve-ment of grain size can simultaneously enhance the toughness and plasticity of the material.Particularly,within this range of line energy,the welded joints with welding speeds of 60 cm/min and 70 cm/min have higher quality if the consistency of welding current and voltage can be maintained.