| The development of metal additive manufacturing technology has promoted the integration of complex and precise parts,and has the characteristics of reducing production time and material consumption,which makes it have broad application prospects.Among them,wire arc additive manufacturing technology（WAAM）,as a kind of metal additive manufacturing technology,has the advantages of low manufacturing cost,high manufacturing freedom and forming efficiency,which is very suitable for the rapid integration and formation of large-sized and medium-low complexity metal components.WAAM are still problems of large shape errors and difficult accuracy control for structural components.This paper uses ER5356 aluminum alloy welding wire as the material for welding forming experiments and optimizes the welding process by adding weaving parameters during the welding process.Based on Weaving Gas Tungsten Arc Welding（W-GTAW）single-layer deposition welding,and uses finite element analysis software ANSYS to simulate the temperature field of the W-GTAW welding process,obtaining the variation law of weaving parameters on welding heat input.Finally,the experiment of weaving arc additive manufacturing is carried out to study the size and forming morphology characteristics of thin wall made by additive under weaving process.Firstly,in the single-pass surfacing experiment,the effects of welding current,tungsten electrode height and weave parameters on the experimental results such as arc morphology and weld formation are mainly analyzed,and the real-time changes of current and voltage and arc morphology are obtained by using high-speed camera and electric signal acquisition system in the welding process.Finally,it is concluded that the radius of arc bottom surface will change with the change of weave parameters,when the weave speed increases to 0.40×10-1rad/s,the change in radius is minimal and only fluctuates by 0.10mm.It is found that lowering the tungsten electrode height,weave angle,and speed can significantly improve welding stability,while reasonable increase of welding angle and speed can increase the depth of the weld.When the welding current is reduced to 130A,the transition from the base metal（BM）hardness value to the heat-affected zone（HAZ）and weld zone（WZ）hardness value is smoother,and the hardness transition value is the smallest.The single-pass W-GTAW temperature field simulation is based on the single-pass surfacing experiment,and the influence of the above parameters on the substrate temperature field and temperature cycle curve is explored by selecting the weave angle,speed and stop time.It is found that the highest temperature in the temperature field during the weave cycle gradually decreases as the heat source moves from the center position of the weld to one side,and the temperature difference between the center and edge of the weld can reach 431℃.Increasing the weave parameters accelerate the diffusion speed of welding heat input to various parts of the base metal.It is found from the weld cloud chart that increasing the weave speed reduce the temperature gradient span at the center of the weld.Compared with the temperature cycle curve,it is found that the larger the weave angle and speed,the lower the peak temperature at the center of the weld,and the higher the peak temperature at the edge of the weld with the increase of weave speed and stop time.Finally,the W-GTAW thin-wall forming experiment is carried out by using the experimental law of single-layer surfacing,and the influence of weave parameters on the forming law and hardness of thin-wall is analyzed.Combined with the electrical signal and arc morphology during welding,the influence mechanism of weave process on arc additive manufacturing is analyzed.The experimental results show that,compared to conventional gas tungsten arc welding（GTAW）additive manufacturing,W-GTAW can achieve a smaller substrate melting amount,higher thin-wall height,and hardness for thin-wall forming.For thin-wall thickness,the wall thickness of W-GTAW-formed parts under the condition of a weave arc stop time of 0.25s is 13.83mm,which is 2.67mm thicker than that of conventional GTAW.Moreover,under this condition,the substrate’s angle of warpage at both ends is only 0.2°.When selecting the middle value of the weave parameters,the thin wall with a maximum size accuracy of 0.92 can be obtained,indicating that appropriately increasing the weave angle and stop time can improve the size accuracy of the thin wall.Regarding the change in hardness,an appropriate increase in the stop time reduced the vertical direction’s hardness fluctuation and make the peak transition smoother. |
