Effect of process parameters on the quality of aluminium alloy Al5Si deposits in wire and arc additive manufacturing using a cold metal transfer process

A 3D print device using a cold metal transfer arc welding station to melt a metallic filler wire is developed to build aluminium part by optimising the process parameters. First tests achieved using standard pre-recorded process parameters allow to study the effect of the travel speed and the average welding power on the geometrical characteristics of mono-layer deposits and on walls built by layers superposition. Finally, a parametric study of the effect of each process parameter controlling the shape of the arc current or voltage and the filler wire feeding is carried out in order to try to improve the geometrical regularity of the deposits, and to better understand the effect of each parameter on the melting of the filler wire, its transfer on the support plate, and the geometry of the formed bead.     

基于BP神经网络的电弧熔丝增材制造数据库系统

通过对电弧熔丝增材制造(Wire and arc additive manufacturing,WAAM)单道焊缝试验数据的分类整理,分析用户需求和使用需要,基于python编程语言下的Django框架,采用B/S架构开发了一个电弧熔丝增材制造数据库系统。试验结果表明,该系统采用数据库与算法预测模型结合的方式开发而成,主要设置了用户权限管理、基本打印数据和焊缝形貌预测三大模块,具有存储扩展打印试验数据功能和预测未知工艺参数下焊缝形貌的功能。不同的打印工艺方法引入不同的BP神经网络结构,使用时数据库系统自动读取库内已有的算法模型或根据已有的试验数据训练新的模型,之后录入试验数据会自动对模型重新训练,实现随数据库内试验数据扩展或修正自动适应的参数预测,能够预测未知工艺参数下的焊缝形貌尺寸。最后,基于MIG工艺设计了1组验证试验对数据库的预测功能效果进行检验,熔宽预测误差为1.3%,余高预测误差为1.5%,说明了数据库系统预测功能的可行性。创新点： 将传统数据库的数据分类存储功能与预测算法相结合,充分发挥了已有试验数据的价值,并且集成了不同试验材料、焊接工艺方法等数据构建算法模型,实现了多种试验条件、焊接工艺方法下的焊接工艺参数预测功能。     

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.     

Local enhancement of the material properties of aluminium sheets by a combination of additive manufacturing and friction stir processing

Friction stir processing (FSP) is combined with additive manufacturing (AM) with selective laser melting to locally enhance the material properties of a metallic part. A groove inside aluminium 1060 alloy sheet is filled with an aluminium 7075 alloy powder by AM. FSP is then applied to the AMed region along the groove. The suggested technique creates a heterogeneous microstructure with alternating reinforcement-enriched and matrix-enriched regions. While the overall hardness of the stir zone (SZ) increases significantly, the heterogeneous microstructure results in a unique uneven hardness distribution in the SZ. Tensile tests confirm the effectiveness of the suggested technique.     

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.     

超声振动对CMT电弧增材制造铝合金组织与性能的影响

为减少电弧增材制造铝合金中的气孔及粗大晶粒,采用超声振动辅助CMT电弧增材制造的方法堆焊4043铝合金薄壁件,研究了超声振幅对沉积态材料微观组织及力学性能的影响。研究发现,熔池内部枝晶在超声振动的作用下发生破碎,使得熔池内部液态金属形核率增大,细化晶粒,粗大柱状晶粒也在熔池振动搅拌下转变为细小等轴晶粒。与未使用超声振动辅助的试样相比,平均晶粒尺寸减少了22.5%。同时超声振动引起的空化及声流效应使得试样中气孔尺寸以及数量减小。但随着超声振幅的增加,熔池内部的能量逐渐加大,热输入的增加也使得晶粒发生粗化现象。过大的超声能量破坏了焊缝的结构完整性,导致焊缝内部出现孔洞。施加超声振动试样的抗拉强度较未施加时上升了8.2%~16.3%,且随着超声振幅的增大,抗拉强度及断后伸长率的各向异性逐渐减小。     

冷金属过渡(CMT)增材制造2219铝合金性能

采用CMT电源的四种模式CMT,CMT-P(脉冲),CMT-ADV(交流)和CMT-PADV(交流脉冲),以2219铝合金丝材为原材料进行增材制造工艺研究。深入分析了不同焊接模式对增材制造时气孔率、孔径分布、显微组织演变和力学性能的影响。为了测试基于CMT电弧增材2219铝合金制件的力学性能,成形了多组单道多层薄壁墙试样,测试结果表明,CMT-PADV模式下制件气孔面积分布率最小,几乎没有直径较大的气孔,制件的晶粒更加均匀细密,析出了细小的第二相Al2Cu颗粒。试样的X射线衍射和力学性能分析表明,CMT-PADV模式下的试样晶格参数最小,溶质Cu的含量最高,试样水平方向的抗拉强度与竖直方向的抗拉强度相差小于5 MPa,并且与其他3种模式相比力学性能有明显提高。     

基于温度函数法的铝合金电弧增材制造残余应力与变形数值模拟

针对TIG电弧增材制造5356铝合金试样不同区域微观组织及性能变化开展研究. 结果表明,试样结合层与沉积层水平交替呈现,底部区域沉积层宽度最大(~ 2.4 mm),中间稳定区最小(~ 1.6 mm);沉积层组织均以等轴晶为主,在灰色基体上弥散分布黑色β-Al₃Mg₂第二相,并伴有少量Mg₂Si和(FeMn)Al₆金属间化合物,结合层存在大量气孔及缩孔等缺陷;底部区域沉积层晶粒尺度最小,而结合层缺陷最多.不同区域水平方向强塑性无明显差异(相似文献   

国内外电子束熔丝沉积增材制造技术发展现状

对冷金属过渡(CMT)的电弧熔丝增材方法制备的Inconel 625合金试样进行不同温度的固溶处理. 研究了固溶处理对所制备的Inconel 625合金的微观组织和力学性能的影响规律. 结果表明,沉积态主要为沿沉积方向生长的柱状枝晶,基体组织主要为γ奥氏体相,在晶粒内和晶界上呈块状或链状分布着大量第二相Laves相以及微小MC颗粒. 固溶温度低于 1 000 ℃时,Laves相和碳化物溶解缓慢,此时固溶处理对合金组织性能的影响较小;当固溶处理温度增加至1 200 ℃时,第二相碳化物溶解,晶粒剧烈长大,并出现大量孪晶界,合金的硬度和抗拉强度有一定程度下降,屈服强度显著下降,断后伸长率显著提升.     

钇含量对电弧增材制造2319铝合金组织与性能的影响

以不同钇含量的2319铝合金丝材为原材料,采用基于冷金属过渡的电弧增材制造工艺(wire arc addictive manufacturing,WAAM)制备2319铝合金,研究了钇含量对WAAM 2139铝合金的显微组织及力学性能的影响. 结果表明,添加Y元素可明显细化直接沉积态WAAM 2319铝合金的晶粒,细晶强化及第二相强化作用显著,间接影响了时效过程析出的二次析出相θ′的数量,同时,未对直接沉积态WAAM 2319铝合金中气孔缺陷的大小、分布产生显著影响. 随着钇含量的增加,合金凝固过程含钇化合物在晶粒交汇处偏析程度增大,使得合金成分过冷度减小,导致WAAM 2319铝合金的晶粒尺寸呈现先减小后增大的趋势,抗拉强度和屈服强度呈现出先上升后下降趋势,断后伸长率逐渐下降. 当钇含量为0.15%时,WAAM 2319铝合金表现出最优的力学性能,即抗拉强度484 MPa、屈服强度348 MPa和断后伸长率10.5%.     

Effects of milling thickness on wire deposition accuracy of hybrid additive/subtractive manufacturing

ABSTRACT

A hybrid technique integrating wire arc additive manufacturing (WAAM) and milling was studied using Al5Si aluminium alloy. The results showed both the surface roughness and the machining allowance of this hybrid additive/subtractive manufacturing were reduced in comparison with pure WAAM when the milling thickness was in the range of 0.4–1.2?mm. The accuracy improvement was discussed in terms of the melt flow. It was found that after the surface was milled to a plane, the melt flow changed from the downward along camber surface to the outward and backflow on the plane. This change slowed down the velocity of melt flow, and then reduces the fluctuation of the side profile of deposited thin wall.     

TC4钛合金电弧增材制造叠层组织特征

采用CMT电弧增材制造技术制造了TC4钛合金薄壁墙构件,并对其组织特征进行了研究. 结果表明,在电弧增材制造过程中,受其热输入、多次热循环及冷却速度的影响,在其构件中产生了从高温保留下来的贯穿数个堆积层的原始β柱状晶晶界、水平层带条纹、马氏体组织和网篮组织等. 显微硬度显示,中下部区域硬度相对较高,平均硬度为336HV 0.1,上部显微硬度有明显降低,平均硬度为323.3HV 0.1.     

异种型号焊丝的铝合金变极性穿孔等离子弧焊缝的组织特征

采用ER4043焊丝作为填充金属,利用变极性穿孔等离子焊接技术制备了2A12铝合金穿孔焊缝,并通过外观和探伤检验了焊接质量.通过扫描电镜和透射电镜等观察并分析了焊缝组织与母材金属的差异,认为焊缝组织由焊丝和母材金属两者熔合而成,并且其强化相也由2种合金材料的强化相组成.在热影响区附近存在较窄的过时效区,并且热影响区内部...     

铝合金激光诱导MIG电弧增材制造成形尺寸规律

为了研究铝合金激光诱导MIG电弧增材制造过程中各参数对薄壁结构件成形尺寸的影响规律,利用二次通用旋转组合方法设计正交试验样本,通过二次回归方程建立了工艺参数（电弧电流I、堆积速度v、层间温度T、激光功率P）与成形墙体稳定区域的尺寸预测模型,并研究了单个工艺参数对试件成形的影响,经验证发现模型预测效果较好.结果表明,当电弧电流大于106 A时,参数对层宽的影响顺序由大到小为,电弧电流、层间温度、堆积速度、激光功率;参数对层高的影响顺序由大到小为,电弧电流、堆积速度、层间温度、激光功率.     

双脉冲电弧增材制造数值模拟与晶粒细化机理

电弧增材制造具有成本低和效率高等优点,然而其晶粒细化的研究鲜有报道. 使用自行研制的熔化极气体保护焊电源实施了双脉冲电弧增材制造试验,通过数值模拟预测了晶粒细化现象,试验结果验证了双脉冲电弧的晶粒细化作用. 结果表明,由于熔池的膨胀,熔池尾部出现了重熔化现象. 在与单脉冲电弧热输入相同时,重熔化现象导致双脉冲电弧能够产生更高的冷却速度,并且细化晶粒. 因此,可以通过改变脉冲参数而不是传统地改变热输入来细化晶粒.     

Development of micro-plasma transferred arc (μ-PTA) wire deposition process for additive layer manufacturing applications

Micro-plasma transferred arc (μ-PTA) deposition process has potential to meet requirements of the meso-sized fabrication and repair of the high value components. This paper reports on the development of μ-PTA as cost effective and energy efficient alternative process for small sized deposition with an overall objective to repair and/or remanufacture the defective dies and molds. An experimental setup was developed to deposit 300 μm diameter wire of AISI P20 tool steel on the substrate of the same material which is one of the most commonly used materials for making the dies and molds used for various applications. Two stage experiments were conducted to indentify the important process parameters generating regular and smooth single bead geometry. The process was further explored for highest possible deposition rate for fabrication of straight walls through multi-layer deposition. The μ-PTA deposition process was found to be capable of fabricating straight walls having total wall width of 2.45 mm and effective wall width of 2.11 mm. The deposition efficiency was found to be 87% for the maximum deposition rate of 42 g/h. The microscopic examination and micro-hardness measurements revealed that the deposited wall is free from cracks, porosity, and inclusions. This study confirms the capability of μ-PTA for ALM in comparison to the existing high energy deposition processes used for meso-scale fabrication and repair applications of the dies and molds. This work confirms that μ-PTA wire deposition process offers the advantages of the laser based processes at much lower cost and more energy efficiency thus making it potential alternative process for repair and remanufacturing of the defective dies and molds. Use of finer wire can further reduce the deposition size enabling μ-PTA wire deposition process to fabricate the miniaturized parts.     

丝材电弧增材制造TA15/TC11梯度结构材料的显微组织和力学性能

利用丝材电弧增材制造的方法制备从TA15过渡为TC11的梯度结构材料,并对该梯度结构材料的晶粒形态、化学成分、显微组织和力学性能沿沉积方向的变化情况进行表征和研究.结果表明,从TA15到TC11,晶粒尺寸减小,并且发生从柱状晶到等轴晶的转变.合金元素的含量在短距离内变化很大,突变区的宽度为800μm.TA15区域和TC...     

碳钢双丝与单丝等离子弧增材制造成形及组织特征分析

针对传统丝材等离子弧增材制造碳钢效率低、质量高的特点,提出了一种"双填丝+压缩等离子弧"增材制造工艺,并采用该工艺增材制造了试样,对比分析了双填丝与单填丝增材制造试样的成形尺寸、显微组织特征和力学性能.结果表明,相对于单填丝等离子弧增材制造工艺,采用新型双填丝等离子弧增材制造工艺,在相同的工艺条件下,熔敷效率提高了0.97倍;平均晶粒尺寸由18.75 μm细化到13.47 μm;试样纵向拉伸抗拉强度提高了62.64 MPa,横向拉伸抗拉强度提高了67.52 MPa;试样有效层的平均显微维氏硬度由158.95 HV0.5增加到175.34 HV0.5.     

铝合金电弧增材制造成形质量研究

基于机器人电弧填丝增材制造成形技术,进行了铝合金零件的成形表面不平整问题的分析及改善方法的试验探究。分析了CMT焊接技术的增材成形效果,以及应用在不同焊道时对成形质量产生的影响;分别探究了起弧与熄弧参数、层间轨迹方式、层间冷却时间等因素对成形质量的影响及改善方法。增材制造翼肋零件中,层间沉积中采用了焊道表面测量,再进行铣削加工的方式,作为进一步探究提高成形质量的试证。结果表明,加大起弧电流、降低熄弧电流,往复的层间轨迹方式及不同层间的冷却时间等方法可以提高零件的成形质量。     

增材制造用高流动性铝合金粉末制备技术研究

采用自主开发的旋转盘离心雾化实验装置进行雾化制备增材制造用铝合金粉末实验研究,通过开展雾化盘实验研究优选出粒度分布较均匀收得率较好的盘形,并获得其结构和工艺参数的影响规律;通过对制得的铝合金粉末性能和3D打印成型件物理性能进行检测.结果表明:离心雾化制备的铝合金粉末具有高流动性、窄粒度、高球形度、高松比,表面光洁无卫星...