Study On The Activating Flux CMT Welding Technology

Carbon-dioxide arc welding had widely applications in the automotive and other fields, but its relatively shallow penetration and obvious welding spatter in rivet welding limited its application in the automotive manufacturing. By the feature of extremely stable arc, low heat input and spatter-free, CMT (Cold Metal Transfer) welding process mainly used in welding sheet metal or super thin plate, dissimilar metal welding, overlay welding and so on. But the characteristics of the smaller weld penetration with CMT welding process, limited its application in the plate welding. In recent years, the activating flux welding has been widely studied, and had great progress.In this paper; we carried out a systematic study of the activating flux CMT welding.Characteristics for the CMT welding process, we determined the unitary welding factors. Using the orthogonal experimental method, we determined the optimal experimental welding parameters. Through the experiments, we developed the welding process plan of this research.We chose nine materials, including Fe2O3, Al₂O₃, and MgCO3 and so on, as the active agents in the activating flux CMT welding. Proposed single and multi-component active agents processing and mixing methods, ensure the active agents to have stable performance and reproducible results. Studied the feasibility program of the Alcohol instead of acetone as the activating flux welding emulsifier, improved the welding conditions.By single Active agent test, we studied the effects of single active agent of the weld penetration, and weld formation and other aspects. From the experimental process and results, we found single-component active agent B₂O₃, SiO₂ and Al₂O₃ significantly increased the weld penetration, and the active agent B₂O₃ and SiO₂ had the worsening trend of the weld formation.By compared the study of the CO₂ and Ar gas protection activating flux welding, we found their arc atmosphere quite different. Due to the characteristics of CO₂ gas, the arc compressed and had a concentration heat. Active agents had an important impact on both physical process of the arc electrode gas ionization and electron emission. Active substances reduced the Ionization voltage, and stabled the welding arc. In activating flux CMT welding, the active agents increased the weld penetration account for the result of arc compression and surface tension. B₂O₃ and SiO₂ had the most significant effects on weld penetration increasing, and it related to the large resistively of the two elements of B and Si.Compared the advantages and disadvantages of various test methods; and we used the uniform design formula to design the active agent ratio with the actual situation. Analyzed and determined the experimental factors and the number of experimental levels, which the prescription uniform design required, and generated a U₁₂ (12⁵) uniform design table. By the uniform experiment we found that, B₂O₃, SiO₂ and Al₂O₃ had a major role in the active agent recipe. Through further experiments, we established a best basis formula PF0. Finally, from the simulation welding tests on the automotive parts, we got a process with weld penetration increased by 20% or more and a stable process, and a good weld formation. The results showed that the activating flux CMT welding had an important significance application prospects and research value.