Research Double Wire AC Cross Arc On Additive Manufacturing Process And Performance

Arc additive manufact uring technology is a tech nology that relies o n welding arc to accumulate discrete materials layer by layer to form a three-di mensional entity.Compared with traditi onal casting and stamping process es,it can greatly redu ce production costs,reduce material waste and shorten the de velopment cycle.In o rder to further improve th e production efficien cy of arc additive manufacturing,the production process of wire arc additive manu facturing is constantly developi ng in the direction of automation and intelligence,especially on the bas i s of the original welding,the development of new high-efficiency welding tech nology,from the welding method itself to improve the effici ency of depositing.In response to the demand for high er effi ciency in the industry,a method of using two welding wir es as fillers during depositing and adding altern ating current between the two wires to improve the effici ency of depositing is proposed to prepare the depositing wall.According to th e main arc current,a ltern ating curr ent voltage and wi re feeding speed,the process method is analyzed,and the influ ence of these parameters on the droplet transition behavior in the additive manu facturing process is obs erved.And on the basis of this m ethod,a double-wire AC cro ss-arc additive manufacturing method is proposed for the prep aration of functionally gradient materials,and t he changing laws of depositing layer formation,microstructure and mechanical properties are an alyzed.In the pro cess o f research on the doubl e-wire AC cross-arc additive manufacturing pro cess,the double-wire AC cross-arc additive manufacturing test platform was first built,and the stainless steel double-wire single-pass single-lay er depositing test was carried out on th e stainless steel subst rate.The current,wire feeding speed ratio an d alt ernating current v oltage are used to stud y the double wire filling process,and t he influence of these parameters on the p arameters such as forming and thermal cycle curv e is explore d.At the same time,th e force analysis of the droplet in the double-wire AC cross arc additive manufacturin g was carried out,and the force o f the droplet was discuss ed wi thout considering the interaction b etween the main arc and the cross arc.On this b a sis,the collected cu rr ent and voltage were combined with the droplet tran sfer.Pro cess to analyze the droplet transition mode.The results show th at the main arc cu rrent,wire feeding speed ratio and AC voltage have a great influence on the depositing formi ng.It is finally det ermined that the m ain arc cu rrent is 80A,the AC vo ltage is 48.4V,and the wire feeding speed of the two welding wires is 110cm/min is the best process parameter.The double-wire AC cross arc consists of a m ain arc and an AC arc.Wh e n the voltage between t he wires is high or the resistance is low,it is ea sier to form a stable arc.At this time,the alternating current has a greater impact on the droplet transfer.Due to the electromagnetic force of the cross arc,the main arc oscilla tes periodically with a p eriod o f 50 Hz,which can stir the molten pool,r efin e the crystal g rains,and improve t he quality of the depositing layer.Both the droplet transfer period and the size o f the droplet are negatively related to the wire feeding sp e ed;with the increas e o f AC voltage,the droplet transfer period and diame ter of the left wire become larger,and the droplet transfer p eriod of the right wire becomes larg er.Th e diameters are all reduced,which is caused by the ch ang e in the arc force be tween the two melting electrodes.On the basis of doubl e-wire AC cross-arc ad ditive manufacturing,t wo kinds of wires are used as fillers to prepare functional ly gradient materials and strengthen the titanium alloy.At the same time,the single-pass and si ngle-layer wire arc additive manufacturing o f gradient titanium alloy mate rials is used.Th e single-ch annel multi-layer depositing wall is optimized for p arameters,and the dep ositing wall with uniform,continuous shape and no obvious defects is obtained.On this basis,the structure and perform ance chang es of the s ample were st udied when the ratio of different wire feeding speeds was different.The results show that the addition of alternating current can make the main arc periodically oscillate,and play a role in stirring the molten pool,which improves th e u nevenness of the c omposition to a certain ext ent.Combined with EDS,it can be seen that the Ni element in the depositing layer is uni formly distributed on the dendrites.Du ring the solidification process,the Ni elem ent an d the Ti elem ent undergo an eutecto id reaction to f o rm a Ti₂Ni metal compound,which is retained duri ng the cooling process.XRD shows that the depositing layer is mainly composed of?-Ti,Ti Ni and Ti₂Ni.The coexistence of Ti Ni and Ti ₂Ni can improve the s trength and toughness of the depositing layer.With the increas e of lncon el 625 wire feeding speed,the hardn ess of th e depositing layer also increas es la yer b y layer,and its hardn ess value can reach 600HV,which is300HV higher than the hardness of the b ase material,and the comp ressive strengt h of the depositing layer has also been greatly improved to 27KN.In the friction and wear test,the area where t he lnconel 625 wire feed speed is faster shows a smaller wear area.The wire arc additive manufacturin g of dissimilar welding wires can significantly imp rove t he wear resistance of t he depositing layer surface.