CMT工艺对Al-Cu合金电弧增材制造气孔的影响

分析不同纯氩保护气体流量和冷金属过渡(CMT)工艺方法对Al-Cu合金电弧填丝增材制造(WAAM)气孔的影响规律。结果表明:纯氩保护气体流量和CMT工艺方法对Al-Cu合金WAAM制造过程的气孔特征均具有重要影响。提高纯氩保护气体流量有助于减少气孔;CMT-PADV工艺因其热输入低及电弧对Al-Cu合金填充丝端部表面氧化膜的高效清理而有利于减少甚至消除气孔,提高纯氩保护气体流量至25 L/min时可消除气孔。  

丝材电弧增材制造技术研究现状及展望

丝材电弧增材制造技术因其成形速度快、成形件尺寸灵活等优点受到越来越多的关注,尤其是大尺寸、复杂形状构件的高效快速成形,丝材电弧增材制造有着其独特的优势.介绍了丝材电弧增材制造技术的工艺过程,从丝材电弧增材制造成形件的成形工艺及表面质量研究、成形件组织性能研究以及成形件残余应力研究三个方面综述国内外丝材电弧增材制造技术的研究现状,总结该技术现阶段在航空航天领域的应用情况,指出研究人员对丝材电弧增材制造技术的相关研究工作聚焦于工艺优化和过程控制两个方向,怎样才能通过熔滴的平稳过渡获得高质量的成形件,如何有效控制逐层堆积过程中晶粒及显微组织变化,以抑制零件内部不良组织的产生是需要继续研究的问题.  

Optimisation of interpass temperature and heat input for wire and arc additive manufacturing 5A06 aluminium alloy

Undulated surface appearance and inconsistent layer cross-sectional dimensions are two common types of appearance defects, which are formed owing to insufficient heat input and nonlinear time-varying thermal boundary condition of molten pool. Appropriate interpass temperature control and heat input regulations are effective ways to realise and maintain the consistent thermal boundary condition during bottom-up additive manufacturing process. Equivalent heat dissipation factor is used to synthetically characterise the variation of heat dissipation in process of additive manufacturing. Combing with Rosenthal's analytical solution, a theoretical model is developed to optimise interpass temperature and heat input for each layer deposition, so as to realise stable additive manufacturing. Finally a specification for the wire and arc additive manufacture procedure was designed according to the developed model which was verified effectively by manufacturing a wall part. It could also be a process design reference for other kinds of metal additive manufacturing.  

电弧增材制造(WAAM)ZL114A铝合金组织与性能的研究

采用金相显微镜、扫描电镜、电子万能试验机等分析测试手段，研究了电弧增材制造工艺方法对ZL114A铝合金组织与性能的影响。与传统铸造成形方法相比，铸态组织具有更小的枝晶间距、Si相细小分布均匀；化学成分可有效控制；T6热处理后，Si相球化充分，第二相弥散分布在α-Al基体上，力学性能显著提升，抗拉强度、屈服强度及延伸率分为360MPa、315MPa、7.5%，延伸率是砂型铸造试样的2.1倍，拉伸断口呈现韧性断裂特征。WAAM成形试样缺陷主要为小于30μm的气孔，经过热处理后气孔数量减少，尺寸有变大趋势。  

ZL205A电弧熔丝增材制造堆积体的组织与性能

用电弧熔丝增材制造技术(WAAM)进行ZL205A铝合金的堆积实验。通过金相、SEM、EDS及拉伸试验,考察堆积体的微观组织和力学性能等,并与金属型铸造试样进行对比。结果发现,堆积体厚度均匀,表面平整,堆积体中元素B和Cd的烧损率分别达到60%和50%。与金属型铸造铸态试样相比较,WAAM直接堆积态晶粒大小更均匀,晶粒尺寸更小,析出相在晶内和晶界上均匀分布。T6热处理后,θ相完全固溶到Al基体中,在晶界上均匀分布着复熔T相,堆积体T6的力学性能达到抗拉强度500Mpa,屈服强度450Mpa,延伸率10%,均高于金属型铸造试样的水平,且试样在横纵两个方向上力学性能一致。  

In-process control of distortion in wire and arc additive manufacturing based on a flexible multi-point support fixture

Distortion induced by non-uniform thermal gradients is one of the major constraints in wire and arc additive manufacturing. A novel flexible multi-point support fixture (FMSF) featured by reconfigured working surface and controllable restraining force is developed as an in-process distortion control technique. FMSF allows the distortion to be suppressed by adjusting the restraining force imposed onto the substrate dynamically as the number of layers increases. Both simulations and experiments are conducted to verify its effectiveness and compare it with other common restraint forms including clamping and pre-springing. The multi-layer deposition results show that a reduction of 96.3% in angular distortion and 86.5% in longitudinal bending distortion are obtained with FMSF, which exhibits great superiority over clamping and pre-springing.