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Ti60合金磁场辅助TIG电弧熔粉增材制造工艺

Magnetic field-assisted TIG arc powder fusion additive manufacturing process of Ti60 alloy

  • 摘要: 为了解决Ti60高温钛合金增材制造致密度低、制丝困难的问题,采用磁场辅助TIG电弧熔粉增材制造方法,并开展相关工艺研究.结果表明,常规TIG电弧熔粉增材制造过程中,粉末在电弧力的作用下易飞离基板,产生严重飞溅.而通过施加横向磁场可改变电弧形貌及其前端电弧力,显著抑制飞溅产生.此外,探究了电流对焊道宏观成形的影响,发现随着电流的增大,焊道的熔宽和熔深显著增大,且均匀性明显改善,球化金属大幅减少.借助高速摄像机拍摄该方法独特的粉末熔化及熔滴过渡过程,粉末经历了不同于丝材的熔滴形成—熔滴长大—熔滴过渡过程.增材制造的Ti60合金墙体试样具有较高强度和优异塑性,横向抗拉强度平均值为1047.0 MPa,断后伸长率为14.1%;纵向抗拉强度为1036.9 MPa,断后伸长率为15.4%.其力学性能优良主要归因于细小的α + β网篮组织及较小的α板条长径比.

     

    Abstract: To solve the problems of low density and difficulty in wire fabrication in the additive manufacturing of Ti60 high-temperature titanium alloy, the magnetic field-assisted TIG arc powder fusion additive manufacturing method was adopted, and related process studies were conducted. The results show that during the conventional TIG arc powder fusion additive manufacturing process, the powder easily flies off the substrate under the action of arc force, producing severe spatter. However, applying a transverse magnetic field changes the arc morphology and its leading arc force, significantly suppressing spatter generation. In addition, the effect of current on the macroscopic forming of the weld bead is investigated. It is found that with the increase of current, the melting width and penetration depth of the weld bead increase significantly; the uniformity of the weld bead improves obviously, and the spheroidized metal decreases substantially. The unique powder melting and droplet transfer processes of this method are captured with a high-speed camera. The powder undergoes a process of droplet formation, droplet growth, and droplet transfer different from that of wire. The additively manufactured Ti60 alloy wall specimens exhibit high strength and excellent plasticity. The average transverse tensile strength is 1 047.0 MPa, and the elongation after fracture is 14.1%; the longitudinal tensile strength is 1 036.9 MPa, and the elongation after fracture is 15.4%. Their excellent mechanical properties are mainly attributed to the fine α + β basketweave microstructure and the small aspect ratio of α laths.

     

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