Study On The Optimization Of Activating Flux And The Microstructure Properties Of 2A12 Aluminum Alloy A-TIG Welding

In order to optimize the welding process and improve the welding performance of2A12 aluminum alloy,the effects of different kinds and combinations of activating agents on the welding properties of 2A12 aluminum alloy were tested by A-TIG welding method.In this study,one or more mixtures of Mn O2,Ti O2,Cao,Si O2,Al2O3,Mg O,Na F,Na Cl,Ca F2,Ca Cl2,Al F3,Al Cl3 and other compounds were selected as the activator in this study.According to the literature,the active agent formula and experimental scheme were reasonably arranged,and the experiment was carried out in strict accordance with the set parameters,and the optimal TIG welding process was determined.The ppearance,internal defects and metallographic structure of the weld were observed.The penetration(depth width ratio),microhardness,welding quality,mechanical properties and chemical composition of the weld were tested.Finally,the test results were analyzed and the conclusion was summarized.The results show that:(1)according to the arrangement of factors,the best TIG welding process of 2A12 aluminum alloy is welding current 110 A,welding speed is 100 mm / min,and current waveform is sine wave;the order of three factors is welding speed > current waveform > welding current,but there is no significant difference among the three factors.(2)The welding seam formed by single oxide activator is relatively straight and smooth,while that formed by single halogen compound activator is relatively rough with black products on the surface.The high melting point of single oxide activator is mainly due to the formation of high current density and surface heat energy in the center of the weld pool by adding a layer of high electronic impedance zone in the peripheral area of the molten pool,thus increasing the weld penetration;at the same time,due to the cation effect in the activating agent,the surface tension gradient of molten pool liquid body is changed(from ne gative to positive),so that the molten pool which originally flows outward and upward changes to the direction However,the melting point of single halogen compound activator is relatively low,and the activating agent absorbs the surrounding electrons du ring evaporation,which makes the arc concentrate,thus increasing the weld penetration.The mechanism of increasing the penetration is slightly different between the two.(3)All the active agents will participate in the formation process of welding seam,the cation in oxide activator plays the main role,and the anion in halogen compound activator plays the main role.(4)Compared with the butt weld without activating agent,the penetration and tensile strength of the butt weld are increased to a certain extent after adding the activating agent;besides the penetration,the thermal stress,inclusions and pores of the weld are important factors affecting the tensile strength of the weld.