Study On AZ91 Magnesium Alloy A-TIG Based On Fly Ash Active Agent

As one of the industrial waste residue with high displacement in China,fly ash has great pollution to the environment,so it is of great significance to comprehensively control and reuse it.Use fly ash preparation to make active agent can waste utilization,turning waste into treasure,saving energy,reducing the cost of active agent and improving the utilization of fly ash.Preparation of composite active agent by using high alumina fly ash and hydrofluoric acid.AZ91 magnesium alloy and the A-TIG welding was carried out to study the fly ash composite active agent.The optimum welding process parameters and the optimum coating amount were determined by orthogonal design.The surface of the welded samples and the measurement of the weld penetration with the spreading area was observed by high-definition digital microscope.The micro structures were analyzed by micro hardness tester.The surface of the weld was scanned by scanning electron microscopy.The welding current and voltage acquisition system was used to simulate the distribution of solute in the weld to collect the current and voltage.The temperature field of the welding process is collected by the temperature field acquisition system.The arc force measurement is carried out by using the arc force measuring device.The flowing state of the molten pool is simulated by fluent software.The high alumina fly ash composite active agent is clarified by welding penetration of AZ91 magnesium alloy A-TIG.The experimental results show that:(1)The fly ash composite active agent mainly by Al2O3,AlF3,SiO2,CaAlF5 composition,fly ash composite active agent’s coating amount of 0.2mg/mm2,the weld surface is well formed,the penetration of the weld is 2.36 mm,1.4 times the sample of the inactive agent,the weld aspect ratio is 0.349,which is 1.43 times the sample of the inactive agent,no significant change in weld hardness.(2)The composite voltage of fly ash increases the average welding voltage by 5V,the temperature field of welding increases on average by about 80 ℃-100 ℃,the welding arc force is increased from 9.7 mN to 21.8 mN.(3)The surface tension and temperature gradient of AZ91 magnesium alloy increases with fly ash composite active agent,the active agent makes the content of Bi particles in the weld center more than that of the weld,the combined action of welding heat input and welding arc and the change of molten metal flow in molten bath lead to the increase of weld penetration.