The dissimilar joints of AZ61 and ZK60 magnesium alloys were obtained by tungsten inert gas arc(TIG)welding and activating tungsten inert gas arc(A-TIG)welding processes.Microstructure characterization shows that,the ...The dissimilar joints of AZ61 and ZK60 magnesium alloys were obtained by tungsten inert gas arc(TIG)welding and activating tungsten inert gas arc(A-TIG)welding processes.Microstructure characterization shows that,the fineα-Mg equiaxed dendrite crystals contained Mg17Al12 and MgZn2 particles in the fusion zone.The average size of theα-Mg grains in the fusion zone was refined to 19μm at welding current of 80 A,which resulted in the largest tensile strength of 207 MPa.The tensile strength and the width of the beam of the A-TIG welded AZ61/ZK60 joints showed strong dependence on the amount of TiO2.However,the inhomogeneity of the heat-affected zone near different base metals presented no significant effect on the mechanical properties of the welded joint.展开更多
A new hybrid welding process was successfully used to join aluminum alloy and stainless steel. In the MIG welding-brazing process, the lower thermal conductivity of steel can cause dramatic change of temperature gradi...A new hybrid welding process was successfully used to join aluminum alloy and stainless steel. In the MIG welding-brazing process, the lower thermal conductivity of steel can cause dramatic change of temperature gradient on steel surface, while the auxiliary TIG arc can change this phenomenon by heating the steel side. The auxiliary TIG improved the wettability of molten metal, resulting in the molten metal spreading fully on upper surfaces, front and back surface of steel, forming a sound brazing joint; the content of Cr and Ni elements in IMCs layer was increased, which can enhance the quality of the layer; and the microstructure of IMCs layer also was improved, increasing the bonding strength with the weld seam. The average tensile strength of the joint obtained with auxiliary TIG arc（146.7 MPa） was higher than that without auxiliary TIG arc（96.7 MPa）.展开更多
A mathematical model is established on the basis of the physical characteristic of the negative resistance arc when a low current of 0—50 A is applied in pulsed TIG welding. The simulation model converted from the ma...A mathematical model is established on the basis of the physical characteristic of the negative resistance arc when a low current of 0—50 A is applied in pulsed TIG welding. The simulation model converted from the mathematical model is run in MATLAB environment, and the discussion is focused on the way the peak current ranging from 29 A to 50 A and the time constant of arc in the span of 0.003—0.006 s influence the simulating results and the dynamic characteristic. The simulating data are close to that of welding experiments and correspond to the theoretical conclusion.展开更多
基金Project(51771160)supported by the National Natural Science Foundation of ChinaProject(2018JJ4048)supported by the Provincial and Municipal Joint Fund for Natural Science of Hunan Province,China
文摘The dissimilar joints of AZ61 and ZK60 magnesium alloys were obtained by tungsten inert gas arc(TIG)welding and activating tungsten inert gas arc(A-TIG)welding processes.Microstructure characterization shows that,the fineα-Mg equiaxed dendrite crystals contained Mg17Al12 and MgZn2 particles in the fusion zone.The average size of theα-Mg grains in the fusion zone was refined to 19μm at welding current of 80 A,which resulted in the largest tensile strength of 207 MPa.The tensile strength and the width of the beam of the A-TIG welded AZ61/ZK60 joints showed strong dependence on the amount of TiO2.However,the inhomogeneity of the heat-affected zone near different base metals presented no significant effect on the mechanical properties of the welded joint.
文摘A new hybrid welding process was successfully used to join aluminum alloy and stainless steel. In the MIG welding-brazing process, the lower thermal conductivity of steel can cause dramatic change of temperature gradient on steel surface, while the auxiliary TIG arc can change this phenomenon by heating the steel side. The auxiliary TIG improved the wettability of molten metal, resulting in the molten metal spreading fully on upper surfaces, front and back surface of steel, forming a sound brazing joint; the content of Cr and Ni elements in IMCs layer was increased, which can enhance the quality of the layer; and the microstructure of IMCs layer also was improved, increasing the bonding strength with the weld seam. The average tensile strength of the joint obtained with auxiliary TIG arc（146.7 MPa） was higher than that without auxiliary TIG arc（96.7 MPa）.
基金National Natural Science Foundation of China (No 59975068) Natural Science Foundation of Tianjin (No993602911)
文摘A mathematical model is established on the basis of the physical characteristic of the negative resistance arc when a low current of 0—50 A is applied in pulsed TIG welding. The simulation model converted from the mathematical model is run in MATLAB environment, and the discussion is focused on the way the peak current ranging from 29 A to 50 A and the time constant of arc in the span of 0.003—0.006 s influence the simulating results and the dynamic characteristic. The simulating data are close to that of welding experiments and correspond to the theoretical conclusion.
