Study On Double-wire Welding Of Dissimilar Materials Between Copper And Steel

A study on the technique concerning double-wire butt welding of copper (T2) - steel (Q235) dissimilar metal sheet is conducted in this paper. Problems including cracks easily occurred in connection of copper-steel dissimilar metal, as well as Cu-side issues such as difficult to weld, etc. are solved through the combination of Cu and Fe wires and adjustment deflecting distance to copper side. When 01.2mm copper wire is applied to the master engine, with the voltage of 26.8V, current of 304A, without involving pulse, while 01.2mm steel wire to the slave engine, involving plus pulse, voltage of 24V, current of 136A, the welding speed and deflecting distance to copper side are expected to reach 65cm/min and 2mm respectively, shaping soundly the welding seam with excellent cracking resistance, without pores, inclusions, cracks, non-fusion involved.Also, tensile strength and hardness tests are conducted towards the copper - steel welded joint. The experimental results show that: the tensile strength of copper - steel double-wire welding joint may reach 220MPa, with the fracture location of Cu-parent metal side in the heat-affected zone and hardness of weld zone ranging between 102～107HB. With SEM, EDAX, optical microscope and other analytical tools employed, an analysis on the organizational structure of welded joints and contents of Cu and Fe in different areas is made. As shown in the results that, Fe content in the weld zone reaches 22.78～26.75%, existing in the form of (α+ε) two-phase solid solution.Analog computation, in addition, is carried out under the temperature field based upon the technique, thus have obtained the temperature distribution at different moments, with thermal recycle curve at both vertical and horizontal sampling points worked out via calculation. Also involved in the paper are discussions on the influence of deflecting distance to copper side on the temperature field, and the fusion of Cu-parent metal, as well as experimental verification of analog results through infrared temperature-test technology, with the result reached in better agreement with the actual data.