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The Research of Coupled Arc AA-TIG Welding

Author: ZuoLiQin
Tutor: FanDing；HuangYong
School: Lanzhou University of Technology
Course: Materials Science
Keywords: AA-TIG welding Coupling arc Best welding process specifications Surface tension temperature coefficient Arc contraction
CLC: TG444
Type: Master's thesis
Year: 2010
Downloads: 44
Quote: 1
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Abstract


In recent years, the activity of TIG welding technology has made great development, but this welding process is still prevalent coating process' complex types and formulations of the active agent development time is too long, and the introduction of the active agent is not easy to accurately control shortcomings. For these deficiencies, by changing the introduction of the active agent, a novel active TIG welding. Recent studies have shown that activating TIG welding, oxygen and other active elements can change the weld pool surface tension temperature coefficient for carbon steel, stainless steel and other steel is the main mechanism of the active agents increased weld penetration. TIG welding arc auxiliary activity, that AA-TIG welding (Arc assisted Activating TIG Welding) single welding torch welding basis, using double the torch welding coupling arc AA-TIG welding. The entire welding process the auxiliary arc and main arc welding, two welding arc mutually independent, process parameters and the action was not the same. The auxiliary arc welding using a certain ratio of Ar CO2 active hybrid protective gas, to replace the coating of the active agent through the weld puddle with a high temperature reactive atmosphere contacting the surface of the bath to produce a thin oxide film, while the main arc TIG welding. Using arc welding gas mixture of Ar CO2 activity protected under the introduction of active elements oxygen, welding current value is smaller, so named for the auxiliary arc; welding workload completed by the another ordinary TIG welding, due to the higher value of the welding current naming The main arc. Coupling arc is a new form of an arc to ensure that smaller spacing arising from the interaction of the two welding arc. Experiment two tungsten TIG welding guns and welding assembly of certain parameters, when the tungsten electrode spacing of less than 3 mm, two welding arc coupled as a whole, the surface of the weld in the welding process can only form a molten pool. Such a welding method can be obtained penetration significant increase in the weld, which is a new kind of applied to a variety of steel active welding method. This selection of SUS304 austenitic stainless steel (0Cr18Ni9) as the base material, as the the auxiliary arc of activity mixed shielding gas, CO2 Ar studied welding current, welding speed, tungsten electrode spacing, activity CO2 content of the gas and the main process parameters such as the coupling arc impact of AA-TIG weld penetration weld width and penetration increase the surface forming a good weld welding process specifications. Optimum welding parameters 1Omm thick base material may not open groove once penetration. Process test results also showed that CO2 gas is mixed in the auxiliary arc to protect the gas content of weld penetration increases greater impact. Coupling arc AA-TIG weld penetration under the optimum welding parameters, significant increase in deep and narrow weld. Compared with ordinary TIG welding, the penetration ratio increased by 1.9 times, while weld penetration reached more than 1.6 times the single arc AA-TIG weld penetration, welding efficiency has improved significantly, weld. Observed microstructure analysis of of active CO2 gas AA-TIG weld microstructure, mechanical properties testing and analysis of the tensile properties of the coupling arc AA-TIG weld, corrosion resistance, hardness and impact toughness changes. Changes in the chemical composition of coupling arc AA-TIG weld and weld tensile fracture surface analysis by electron microprobe and a scanning electron microscope analysis. The test results show that the addition to the weld impact toughness certain decline, the coupling arc AA-TIG weld the performance and the chemical ingredients are coupled arc TIG welding little difference. To this end the guarantee under the premise of weld penetration increased to strictly control the content of CO2 gas, in order to reduce the adverse effects of oxygen on the weld. , Increased penetration mechanism, the first through the analysis of the arc shape and the welding voltage, studied the influence of the arc characteristics of the depth of penetration increase; Secondly, through the electronic probe testing of oxygen and carbon element content and morphology, analysis of oxygen surface tension mechanism. The results again verify the arc contraction and increase of the arc voltage is not the depth of penetration increase is mainly due to oxygen as active elements can change the stainless steel bath surface tension temperature coefficient is the main mechanism for coupling arc AA-TIG weld penetration increase. Coupling arc wide application range of AA-TIG welding method can be used not only to a variety of mixed gas as the active welding shielding gases, and in a variety of steel products in the application can be fully automated production, such as energy-efficient features, is a potentially development and application of the value of new welding technology.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > Arc welding
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