Research On Arc Characteristics,Microstructure And Mechamical Properties Of Weld Bead By Fly Ash Active Flux TIG

Fly ash is a major waste solid from coal-fired power plants,the comprehensive utilization of fly ash,waste change for profit,has become an important technical and economic policies of China.It is an important means to solve the conflict between environment pollution of power production and lack of resource in our country.As we know,the composition of fly ash such as SiO₂,Al₂O₃ and alkali metal oxide can be used as active flux.In order to improve the efficiency of TIG welding and reduce the cost of active flux,we use fly ash as active flux and study its effect on welding arc and weld seam.Firstly,real time acquisition system of welding arc characteristics and welding thermal cycle,arc diameter measuring and arc force test device were made.The variation of current voltage,welding thermal cycle,arc diameter and arc force of coated fly ash was analyzed.Then the effects of SiO₂ and Al₂O₃ mixed powder on weld morphology,microstructure and welding arc were studied.On the basis of the influence of active flux on characteristics of welding arc,then expound the active agent mechanism of fly ash.At last,the morphology,microstructure and properties of Q235 steel weld were studied by using fly ash as active flux.The experimental results shows:The weld penetration depth of the high alumina fly ash is2.61mm,which is 1.7 times of no active flux and the weld penetration depth of the high silicon fly ash is 3.19mm,which is 2.1 times of no active flux.Coating fly ash active flux can increase welding arc voltage,electric arc,weld temperature and electric arc.Under the combined action of heat and force,the weld penetration depth increases.SiO₂ in fly ash plays a major role in the weld penetration and the refinement of microstructure.However,the pure SiO₂ active flux is not good in weld formation and the presence of Al₂O₃ can play a role in improving weld formation.The mechanical properties and corrosion resistance of high alumina fly ash and high silicon fly ash are better than those without active fluxs,and the latter is particularly prominent.Q235 as the base metal,coating high alumina fly ash and high silicon fly ash have good weld.