Experimental Investigation Of The Process Parameters Of Wire Arc Additive Manufacturing For Magnesium Alloy

As the lightest structural alloys,magnesium alloys have attracted great attention in recent years due to its many excellent properties such as high specific strength etc.Magnesium alloys play an important role in reducing weight and realizing energy saving and emission reduction,and the application prospect is very promising,while it also puts forward higher requirements for the properties of magnesium alloy.In order to realize further lightweight,developing monolithic components is an important trend for the application of magnesium alloy.Wire arc additive manufacturing?WAAM?offers a potential approach to fabricate large-scale magnesium alloy components with low cost and high efficiency.At present,AZ31 magnesium alloy is the most widely used among all wrought magnesium alloys.In this study,WAAM is preliminarily applied to fabricate AZ31 magnesium.Fully dense AZ31 magnesium alloy components are successfully obtained.Meanwhile,the effects of process parameters on the macrostructure,microstructure and tensile properties are investigated.From this investigation,the important conclusions are as follows:?1?As alternating current frequency,pulse frequency and wire feed rate increase,or alternating current and welding speed decrease,the surface morphologies of the additively manufactured samples become smoother.?2?Alternating current,wire feed rate and welding speed have a remarkable influence on the geometry of deposited layers,while alternating current frequency and pulse frequency have little effect on the geometry of deposited layers.As alternating current frequency and wire feed rate increase,or alternating current and welding speed decrease,the layer thickness increases.As alternating current frequency,wire feed rate and welding speed increase,or alternating current decreases,the maximum width decreases.As pulse frequency increases,the layer thickness decreases firstly and then increases and remains stable,while the maximum width increases firstly and then decreases to a certain value.?3?Alternating current frequency,pulse frequency,wire feed rate and welding speed have an appreciable influence on grain size,while alternating current has little effect on grain size.As alternating current frequency,wire feed rate and welding speed increase,grain size decreases.As pulse frequency increases,grain size decreases firstly and then increases.As alternating current increases,grain size increases slightly.?4?Alternating current frequency and pulse frequency have a great influence on tensile properties,while alternating current,wire feed rate and welding speed have little effect on tensile properties.As alternating current frequency increases,tensile properties decrease.As pulse frequency increases,tensile strength increases firstly and then decreases.As wire feed rate and welding speed increase,tensile strength increases slightly.?5?Fine equiaxed grains and good tensile properties can be obtained at appropriate process parameters.The additively manufactured samples in this study contain finer equiaxed grains?21?m?and exhibit higher ultimate tensile strength?261 MPa?and yield strength?102MPa?,which are similar to those of the forged AZ31B alloy.Moreover,their elongation is above 23%,which means good plasticity.?6?According to Hall-Petch equation,the relationship between yield strength and grain size of wire arc additive manufactured AZ31 magnesium alloy is ?_y=24+342d^-1/2.