| TiAl alloys have very broad application in the field of key aerospace parts due to the good high temperature oxidation resistance,high specific strength,and light weight.Wire-arc additive manufacturing is an additive technology based on arc accumulation deposition combined with robot intelligent control.It has the advantages of low equipment cost,high deposition flexibility,high efficiency,and no working space constraints.It has a very good application prospect in the field of TiAl alloy manufacturing,which has attracted great attention and has carried out a lot of researches on it.However,there is no domestic research on the preparation of TiAl alloy using wire-arc additive manufacturing technology.This article used plasma arc welding and gas tungsten arc welding additive manufacturing systems based on twin-wire system to fabricate TiAl alloys.Morphology and mechanical properties were subsequently studied.Besides,the effect of welding travel speed and process on the performance of additively manufactured TiAl alloys was also investigated.In this study,a plasma arc welding additive manufacturing system of TiAl alloy was built,and the microstructure of TiAl alloy was analyzed by metallographic microscope.According to the obtained results,the microstructure of the plasma arc based wire-arc additive manufacturing prepared TiAl alloy mainly showed a lamellar structure in the middle area,which was mainly composed of α2 phase and γ phase.The component presented an equiaxed crystal morphology in the near-substrate zone,and it formed a dendritic morphology in the top region due to rapid cooling.The Al content of the prepared TiAl alloy was approximately 45 at%.The mechanical properties were also studied.The hardness of TiAl alloy was407.33 Hv and the tensile strength of the TiAl alloy in the three directions of 0°,45° and 90° was tested.and it’s the best tensile strength in the 0°direction was 400.16 MPa.The results indicated that the the TiAl alloy has good mechanical properties,which verifies the use of PAW process promotive.The process is of great significance for TiAl alloy fabrication.This study further explored the influence of the welding travel speed on the PAW process on the additive manufacturing of TiAl alloys,because changing the welding travel speed will change the heat input,which in turn would lead to changes in the properties of the TiAl alloy.The results showed that the TiAl alloy still presents a microstructure consisting of three parts contained the near the substrate zone,the middle region and the top region.The TiAl alloy prepared by the low welding travel speed has less α2 phases,and its hardness was 375.43 Hv.The tensile strength of the TiAl alloy was also measured at 0°,45°,and 90°.Tensile strength in all directions also showed anisotropy,and its tensile strength in the 0° direction was best383.05 MPa,which is lower than that at the high welding travel speed.Different additive preparation processes will also have a certain impact on the properties of TiAl alloys.This article further used the GTAW process to prepare TiAl alloys.The microstructure of the TiAl alloy also showed different morphologies in the near the substrate area,the middle area and the top area.The α2 phase composition was found to be lower than that of TiAl alloy using PAW process.The hardness of the prepared TiAl alloy was322.85 Hv.and its tensile properties were anisotropic,and its tensile properties in the 0° direction were best 378.41 MPa,which was lower than that prepared by PAW process.Therefore,the TiAl alloy prepared by the PAW process had better performance. |
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