| 摘要: |
| 等离子弧增材制造技术具有低成本、高沉积率和高材料利用率等优势，对航空航天、海洋工程及军事医学等领域的大型复杂零件制造具有重要意义。但等离子弧能量密度高及钛合金热导率低的特性，导致钛合金沉积零件成形性差，且易生成粗大柱状晶。另外，等离子弧增材制造工艺参数多和调控难的特点，限制了满足力学标准的增材制造工艺参数的快速制定。 采用正交试验法、金相组织分析及组织与力学能关系表征等手段，研究等离子弧增材制造 Ti-6Al-4V 工艺参数对成形性、显微组织及显微硬度的影响规律。研究结果表明，等离子弧工艺参数对成形性的影响程度依次为基值电流（Ib）＞峰值电流（Ip） ＞占空比（Idcy）＞送丝速度（TWFS）＞沉积速度（Ts）＞脉冲频率（FP），且基值电流对单道沉积层的熔宽、余高和成形性的影响最大；对平均晶粒尺寸的影响程度依次为 Ts＞FP＞TWFS＞Ib＞Ip＞Idcy，沉积速度越大，晶粒尺寸越小，脉冲频率影响次之；对显微硬度影响程度依次为 Ts＞Idcy＞TWFS＞Ib＞FP＞Ip，沉积速度对平均晶粒尺寸和显微硬度影响最大，峰值电流对平均晶粒尺寸及显微硬度的影响有限。研究结果可为等离子弧增材制造及再制造工艺提供理论依据，并为野外矿山机械、海洋船舶、工程装备平台及石油化工装备等受损零件的快速修复提供工艺调控技术参考。 |
| 关键词: Ti-6Al-4V 等离子弧增材制造 正交试验 成形性 显微硬度 |
| DOI：10.11933/j.issn.1007-9289.20221231003 |
| 分类号:TG156；TB114 |
| 基金项目:国家自然科学基金资助项目(51805331) |
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| Effects of Process Parameters on Formability and Microhardness in Plasma Arc Additive Manufacturing of Ti-6Al-4V Alloy |
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WU Xiangju1, GUO Dengji1,2, LIN Jianjun1,2, WANG Xujin1
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1.Institute of Semiconductor Manufacturing Research, Shenzhen University,Shenzhen 518060 , China;2.Shenzhen Key Laboratory of High Performance Special Manufacturing,Shenzhen University, Shenzhen 518060 , China
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| Abstract: |
| Titanium alloys offer the advantages of low density, high specific strength, and good corrosion resistance, making them widely used in aerospace, ocean engineering, military medicine, and other fields. However, the high cost, low thermal conductivity, and low elastic modulus of titanium alloys result in poor quality, low efficiency, and high cost of traditional processing, which seriously restricts their application and development. Plasma-arc additive manufacturing technology provides a cost-effective solution with high deposition and material utilization rates, which is crucial for the production of large and complex parts. However, owing to the high energy density of the plasma arc and the low thermal conductivity of titanium alloys, the formability of titanium alloy-deposited parts is compromised, resulting in the growth of coarse columnar grains. In addition, the characteristics of many parameters and the difficulty in controlling plasma-arc additive manufacturing limit the rapid formulation of additive manufacturing process parameters that meet mechanical standards. The influence of plasma arc additive manufacturing of Ti-6Al-4V alloy process parameters on formability, microstructure, and microhardness was investigated by orthogonal experiments, metallographic analysis, and characterization of the relationship between the microstructure and mechanical properties. The experiment was conducted in an inert argon gas environment using a plasma arc additive manufacturing system, which consists of a Kuka robot, main power supply, plasma power supply, and wire feeding system. The main process parameters included deposition speed, wire feeding speed, pulse base current, pulse peak current, pulse frequency, and duty cycle. The three main evaluation parameters of formability were evaluated using the melting width, reinforcement, and aspect ratio of the deposited layer as indicators. In addition, the average grain size and microhardness were used as indices to evaluate the effect of microstructure on mechanical properties. The results indicate that the degree of influence of the plasma arc process parameters on the formability is as follows: base current (Ib) ＞ peak current (Ip) ＞ duty cycle (Idcy) ＞ wire feed speed (TWFS) ＞ deposition speed (Ts) ＞ pulse frequency (FP). Ib has the greatest influence on the deposited width, deposited height, and formability of a single layer, with a more pronounced effect when Ib is 50%-70% Ip. The deposition speed and duty cycle exhibited the following relationships: the faster the deposition speed, the smaller the width and height of the deposition layer. The effect of the duty cycle on the width and formability of the single-pass deposited layers was positively correlated. The effect of process parameters on the average grain size was Ts＞FP＞TWFS＞Ib＞Ip＞Idcy, with larger deposition speeds resulting in smaller grain sizes. Pulse frequency was the second most influential parameter on average grain size, demonstrating that pulse disturbance aids in grain refinement. Moreover, the degree of influence of the process parameters on microhardness was Ts ＞ Idcy ＞ TWFS ＞ Ib ＞ FP ＞ Ip. The deposition speed had the greatest influence on average grain size and microhardness, with Ip having limited influence on these two aspects. Although the influence of the deposition speed on microhardness was the greatest, the degree of influence was only 4%, indicating that the influence of the selected plasma-arc process parameters on microhardness was not significant. These findings provide a theoretical basis for plasma arc additive manufacturing and additive remanufacturing processes and offer technical support for the rapid repair of damaged parts in applications such as field mining machinery, marine ships, engineering equipment platforms, and petroleum and chemical equipment. |
| Key words: Ti-6Al-4V plasma arc additive manufacturing orthogonal experiment formability microhardness |
