Enhanced Strength-Ductility Synergy in Submerged Friction Stir Processing ER2319 Alloy Manufactured by Wire-Arc Additive Manufacturing via Creating Ultrafine Microstructure

Submerged friction stir processing(SFSP)with flowing water was employed to alleviate the porosities and coarse-grained structure introduced by wire-arc manufacturing.As a result,uniform and ultrafine grained(UFG)structure with average grain size of 0.83μm was achieved with the help of sharply reduced heat input and holding time at elevated temperature.The optimized UFG structure enabled a superior combination of strength and ductility with high ultimate tensile strength and elongation of 273.17 MPa and 15.39%.Specifically,grain refinement strengthening and decentralized θ(Al_(2)Cu)phase in the sample subjected to SFSP made great contributions to the enhanced strength.In addition,the decrease in residual stresses and removal of pores substantially enhance the ductility.High rates of cooling and low temperature cycling,which are facilitated by the water-cooling environment throughout the machining process,are vital in obtaining superior microstructures.This work provides a new method for developing a uniform and UFG structure with excellent mechanical properties.

Additive friction stir deposition of AZ31B magnesium alloy

The current work explored additive friction stir deposition of AZ31B magnesium alloy with the aid of MELD?technology.AZ31B magnesium bar stock was fed through a hollow friction stir tool rotating at constant velocity of 400 rpm and translating at linear velocity varied from 4.2 to 6.3 mm/s.A single wall consisting of five layers with each layer of 140×40×1 mm^(3)dimensions was deposited under each processing condition.Microstructure,phase,and crystallographic texture evolutions as a function of additive friction stir deposition parameters were studied with the aid of scanning electron microscopy including electron back scatter diffraction and X-ray diffraction.Both feed material and additively produced samples consisted of theα-Mg phase.The additively produced samples exhibited a refined grain structure compared to the feed material.The feed material appeared to have a weak basal texture,while the additively produced samples experienced a strengthening of this basal texture.The additively produced samples showed a marginally higher hardness compared to the feed material.The current work provided a pathway for solid state additive manufacturing of Mg suitable for structural applications such as automotive components and consumable biomedical implants.

Improvement of microstructure and fatigue performance of wire-arc additive manufacture d 4043 aluminum alloy assiste d by interlayer friction stir processing

To expand the application of wire-arc additive manufacturing(WAAM)in aluminum alloy forming com-ponents,it is vitally important to reduce the porosity,refine microstructure,and thereby improve the mechanical properties of the components.In this study,the interlayer friction stir processing(FSP)tech-nique was employed to assist the WAAM of 4043 Al-Si alloy,and the related effects on the microstruc-ture evolutions and mechanical properties of the fabricated builds were systematacially investigated.As compared to the conventional WAAM processing of Al-Si alloy,it was found that the introduction of in-terlayer FSP can effectively eliminate the pores,and both theα-Al dendrites and Si-rich eutectic network were severely broken up,leading to a remarkable enhancement in ductility and fatigue performance.The average yield strength(YS)and ultimate tensile strength(UTS)of the Al-based components produced by the combination of WAAM and interlayer FSP methods were 88 and 148 MPa,respectively.Meanwhile,the elongation(EL)of 37.5%and 28.8%can be achieved in the horizontal and vertical directions,respec-tively.Such anisotropy of EL was attributed to the inhomogeneous microstructure in the stir zone(SZ).Notably,the stress concentration can be effectively reduced by the elimination of porosity and Si-rich eu-tectic network fragmentation by the interlayer FSP,and thus the fatigue behavior was improved with the fatigue strength and elongation increased by∼28%and∼108.7%,respectively.It is anticipated that this study will provide a powerful strategy and theoretical guidance for the WAAM fabrication of Al-based alloy components with high ductility and fatigue performance.

Integrated Modeling of Process–Microstructure–Property Relations in Friction Stir Additive Manufacturing

Friction stir additive manufacturing is a newly developed solid-state additive manufacturing technology.The material in the stirring zone can be re-stirred and reheated,and mechanical properties can be changed along the building direction.An integrated model is developed to investigate the internal relations of process,microstructure and mechanical properties.Moving heat source model is used to simulate the friction stir additive manufacturing process to obtain the temperature histories,which are used in the following microstructural simulations.Monte Carlo method is used for simulation of recrystallization and grain growth.Precipitate evolution model is used for calculation of precipitate size distributions.Mechanical property is then predicted.Experiments are used for validation of the predicted grains and hardness.Results indicate that the average grain sizes on diff erent layers depend on the temperature in stirring and re-stirring processes.With the increase in building height,average grain size is decreased and hardness is increased.The increase in layer thickness can lead to temperature decrease in reheating and re-stirring processes and then lead to the decrease in average grain size and increase of hardness in stir zone.

Enhancing the mechanical performance of Al-Zn-Mg alloy builds fabricated via underwater friction stir additive manufacturing and post-processing aging

Our previous studies have demonstrated that underwater friction stir additive manufacturing(FSAM)could effectively suppress the macroscale softening of the fabricated Al-Zn-Mg-Cu alloy build from top to bottom.However,the accompanying local softening problem,i.e.,a low-hardness region at the bottom of each stir zone,becomes prominent.In this study,an Al-Zn-Mg alloy with low quench sensitivity was used to fabricate a multilayered build via underwater FSAM.In-process water cooling could effectively solve the macroscale and local softening problems in the FSAM of the Al-Zn-Mg alloy and improve the mechanical performance of the build.The microhardness and ultimate tensile strength(UTS)of the water-cooled build in as-fabricated and aged states were more uniform along the building direction and higher than those of their counterparts.After 90 days of natural aging,the UTS of the water-cooled build in building and traveling directions reached 398 and 400 MPa,respectively,slightly higher than that of the base metal(392 MPa).The enhancement in the mechanical performance of the water-cooled build was attributed to a high degree of supersaturation and age-strengthening ability because of a high cooling rate of the underwater FSAM process and low quench sensitivity of the base metal.

Chemical Composition Effect on Microstructures and Mechanical Properties in Friction Stir Additive Manufacturing

The variation of chemical compositions can affect the mechanical property of friction stir additive manufacturing(FSAM).Quantitative characterization of the relationship between the chemical composition and the mechanical property of FSAM components is key to control the quality of FSAM components.The effect of chemical composition on the mechanical property of 6 xxx series aluminum alloy FSAM joint was studied by both experimental and numerical methods.A moving heat source model was established to simulate the heat transfer in FSAM process.The average grain size was calculated by Monte Carlo model,and the precipitate evolution model was used to calculate the hardness and constitutive stress-strain relationship.The validity of the numerical model was verified by experiments.Results indicate that the hardness and yield stress of 6 xxx series aluminum alloy FSAW joint can be enhanced by increasing silicon or magnesium contents.By increasing the content of magnesium(silicon),the volume fraction and the mean radius of MgSi can be increased when the content of silicon(magnesium) is excessive.With the decrease in volume fraction,the average grain size can be increased.By changing the weight percentage of magnesium and silicon in different layers,the hardness and yield stress along the build direction can be controlled.

3D printing of fine-grained aluminum alloys through extrusion-based additive manufacturing:Microstructure and property characterization

Additive manufacturing(AM)has the potential to transform manufacturing by enabling previously un-thinkable products,digital inventory and delivery,and distributed manufacturing.Here we presented an extrusion-based metal AM method(refer to“SoftTouch”depositionin thefiledpatent)thatis suitablefor making the metal feedstock flowable prior to the deposition through dynamic recrystallization induced grain refinement at elevated temperatures.The flowable metal was extruded out of the printer head like a paste for building dense metal parts with fine equiaxed grains and wrought mechanical properties.Off-the-shelf metal rods were used as feedstock and the printing process was completed in an open-air environment,avoiding pricy powders and costly inert or vacuum conditions.The resulting multi-layer de-posited 6061 aluminum alloys yield strength and ductility comparable to wrought 6061 aluminum alloys after the same T6 heat treatment.The extrusion-based metal AM method can also be advanced as green manufacturing technologies for fabricating novel alloys and composites,adding novel features to existing parts,repairing damaged metal parts,and welding advanced metals for supporting sustainable manufac-turing,in addition to being developed into a cost-effective manufacturing process for the fabrication of dense metal of complex structural forms.

固相搅拌摩擦沉积增材制造技术研究进展

搅拌摩擦沉积增材(Additive friction stir deposition,AFSD)是一种先进的固相增材制造(Additive manufacturing, AM)技术。与传统基于熔融的增材制造技术相比,它具有增材结构致密、材料低变形和过程高效节能等优势,在航空装备制造、交通运输、机械制造等领域拥有广阔的应用前景。本文综述了AFSD技术的原理、优势、组织演变特点和应用情况。重点介绍了AFSD过程中“工艺条件-微观组织-力学性能”相关性的研究现状,沉积材料力学性能受材料流动状态、界面连接机制、微观组织演变情况的综合影响。列举了AFSD技术在大型构件整体制造、高性能涂层、表面缺陷修复等领域的应用。最后,对AFSD技术进行了展望,指出该技术在工艺与组织变化耦合、原位变形条件模拟、工具头设计和新材料增材等方面需进一步研究和突破。

侧向搅拌摩擦增材制造工艺优化与力学性能特征分析

为研究侧向搅拌摩擦增材制造工艺参数对增材区材料力学性能的影响,建立了响应面模型,对模型进行了回归分析,基于响应面法对工艺参数进行了优化,并通过方差分析验证了模型的可靠性。结果表明,在增材参数为旋转速度为982.81r·min^(-1),增材速度为36.147mm·min^(-1),下压量为2.428mm时增材区的最大抗拉强度为252.72MPa,断后伸长率为11.82%。根据工艺过程对最优工艺参数进行修正,随后进行5层侧向搅拌摩擦增材制造试验,并进行力学性能特征分析。结果表明,修正后最优工艺参数下增材区拉伸性能与母材性能相当,拉伸试件断裂方式为韧性断裂;后一层增材区硬度高于前一层增材区。

In-vitro biomineralization and biocompatibility of friction stir additively manufactured AZ31B magnesium alloy-hydroxyapatite composites

The present study aims to evaluate effect of hydroxyapatite(HA,Ca10(PO4)6OH2),a ceramic similar to natural bone,into AZ31B Mg alloy matrix on biomineralization and biocompatibility.The novel friction stir processing additive manufacturing route was employed to fabricate Mg-HA composites.Various HA contents(5,10,20 wt%)were incorporated into Mg matrix.Microstructural observation and chemical composition analysis revealed that refined Mg grains and dispersion of HA particles at micro/nanoscales were achieved in Mg-HA composites after the friction stir processing.The biomineralization evaluation were carried out using immersion experiments in simulated body fluid followed by mineral morphology observation and chemical composition analysis.The wettability measurements were conducted to correlate the biomineralization behavior.The results showed improvement in wettability and bone-like Ca/P ratio in apatite deposit on the composites compared to as-received Mg.In addition,the increase of blood compatibility,cell viability and spreading were found in the higher HA content composites,indicating the improved biocompatibility.Therefore,friction stir processed Mg-20 wt%HA composite exhibited the highest wettability and better cell adhesion among other composites due to the effect of increased HA content within Mg matrix.

搅拌摩擦增材制造方法研究进展

通过文献研究,将目前现有的搅拌摩擦增材技术分为两个大类:基于搅拌摩擦搭接焊的以板材为原材料的“搅拌摩擦搭接增材(FSAM)”与以棒材或丝材为原材料的“搅拌摩擦沉积增材(AFSD)”。重点综述了迄今已公开报道的三种方法:采用“实心轴肩+板材”的搅拌摩擦增材技术、“空心轴肩+棒材”的搅拌摩擦沉积增材技术、“空心轴肩+丝材”的搅拌摩擦沉积增材技术。其中后两种搅拌摩擦增材方法具有可连续增材的优越性,应用前景广阔。

搅拌摩擦增材制造2024-T6铝合金增材区性能分析

用搅拌摩擦增材制造技术对2024-T6铝合金进行增材试验,观察增材区显微组织,结合显微硬度对增材区摩擦磨损性能进行分析,探索搅拌头行进速度对增材区性能的影响规律。结果表明:当搅拌头旋转速度为1000 r/min,行进速度为150~250 mm/min时,增材区成形良好,无明显缺陷;各参数下试样晶粒得到细化,增材区晶粒尺寸沿增材厚度方向逐渐减小,显微硬度沿增材厚度方向逐渐增大;随着搅拌头行进速度增大,试样显微硬度先增后减,同时摩擦磨损性能先变好后变差,当行进速度为200 mm/min时,显微硬度和摩擦磨损性能最佳。

搅拌摩擦增材制造技术研究进展

搅拌摩擦增材制造技术是一种全新的固相增材工艺,具有增材效率高、材料范围广、性能优、成本低等优点。搅拌摩擦增材制造方法主要分为板材叠加增材制造、搅拌摩擦沉积增材制造和损耗型摩擦堆焊增材制造。本文对搅拌摩擦增材制造技术的基本原理、沉积层微观组织演变和力学性能进行了论述,最后对搅拌摩擦增材制造技术的潜在应用进行了展望。

搅拌摩擦辅助电弧增材制造铝合金研究进展

高性能铝合金兼具轻质、高强、耐腐蚀等优点,在航空航天和汽车制造等工业领域应用前景广阔。电弧增材制造技术集成形效率高、原材料和设备成本低、环境适应性强等优点于一身,在大尺寸铝合金构件制备方面具有显著优势。但复杂热循环导致的晶粒粗大、组织不均匀、残余应力和气孔缺陷等问题,给电弧增材制造铝合金带来了挑战。搅拌摩擦加工技术具有良好的组织细化、均匀化和致密化效果,已作为同步调控或后处理手段用于铝合金的增材制造中。针对近年来搅拌摩擦辅助电弧增材制造铝合金的装备系统、工艺参数、组织结构和力学性能等方面进行了综述,并分析了搅拌摩擦辅助电弧增材制造技术的形性调控机理,最后对复合增材制造技术的发展趋势进行了展望。

2195铝锂合金搅拌摩擦增材制造成形与性能研究

搅拌摩擦增材制造作为一种新型固相增材制造技术,能够有效避免高强铝锂合金元素烧损的同时获得高性能增材构件。本文提出自限位搅拌摩擦增材制造方法,以铝锂合金带材为原料制备多层增材结构件。结果表明,搅拌摩擦增材区内材料流动充分,层间冶金结合良好。增材层晶粒尺寸和沉淀相分布主要受热–机械效应影响,搅拌道次越少的区域,热机效应小,沉淀相越多,硬度越高。单层增材厚度1 mm,增材速率达200 mm/min,增材区硬度最高为126.8HV,达到2195–T8铝锂合金的79.3%。同时,由于部分Cu元素固溶于增材区,搅拌摩擦固相增材区的耐腐蚀性能优于母材。

冷喷摩擦复合增材制造6061铝合金的显微组织、力学性能和腐蚀行为

采用冷喷摩擦复合增材制造(CFAM)技术制备6061铝合金块体材料。采用OM、SEM和EBSD对冷喷涂(CS)和CFAM试样的显微组织进行表征,通过显微硬度、拉伸和腐蚀实验研究两者的力学性能和腐蚀行为。结果表明,与CS试样相比,CFAM试样的显微组织更加致密和均匀,晶粒细小等轴,平均晶粒尺寸为3.1μm,显微硬度、极限抗拉强度和伸长率分别提高了22%、171%和683%。CFAM试样的腐蚀电流密度比CS试样低95.1%~97.8%,腐蚀机理由CS试样的点腐蚀转变为晶间腐蚀。

“电弧+搅拌摩擦”复合增材制造铝/钢的组织和耐腐蚀性分析

为了实现铝/钢复合结构的灵活制造,提出了“电弧+搅拌摩擦”复合增材制造的新方法,即先利用旁路分流熔化极惰性气体保护焊在镀锌的Q235钢表面沉积一层薄的铝合金过渡层,再搅拌摩擦增材制造过渡层和6061铝合金.在电弧沉积过渡层过程中,镀锌层和旁路电弧促进了液滴在钢表面的润湿性和铺展性,获得了平整的表面成形,随后的搅拌摩擦增材制造过程消除了过渡层的气孔和裂纹缺陷,获得了表面成形良好且无缺陷的铝/钢复合结构.研究了不同焊丝成分(Al-Si,Al-Mg)对铝/钢复合结构的组织和耐腐蚀性能影响,结果表明,焊丝成分不会影响焊缝成形,但会影响界面金属间化合物层厚度,Al-Si焊丝的Si元素偏聚在铝/钢界面层附近,可以有效阻止Fe,Al元素的相互扩散,减少金属间化合物的产生.同时填充Al-Si焊丝的铝/钢结构耐腐蚀性好于填充Al-Mg焊丝,这是因为受到界面层金属间化合物的影响,金属间化合物会和基体发生电偶腐蚀,优先腐蚀铝基体,降低铝/钢复合结构耐腐蚀性能.创新点:(1)提出了一种“电弧+搅拌摩擦”复合增材制造铝/钢异种金属的新方法,解决了搅拌针和钢直接接触导致搅拌针受损的问题,同时通过搅拌摩擦增材使电弧堆焊过渡层产生的孔隙和裂纹等缺陷被消除.(2)相比于Al-Mg焊丝,Al-Si焊丝作为过渡层填充材料可以有减少金属间化合物,进而抑制组件电偶腐蚀.

高强铝合金搅拌摩擦类增材制造研究进展

增材制造技术作为传统材料制备与加工方式的有效补充,有望满足先进制造领域对大尺寸、高性能构件短周期制备的新需求。基于能量束的熔化增材制造在使用商业高强铝合金制备大构件时难以避免凝固缺陷,导致所制备构件的材料力学性能下降。搅拌摩擦类增材制造技术避免了凝固缺陷,增材构件致密、组织均匀、晶粒细小、织构较弱,提升了增材构件材料的综合力学性能。本文对搅拌摩擦类增材制造技术在制备高强铝合金方面的研究与应用进展展开综述,分析了搅拌摩擦类增材制造技术面临的挑战及发展趋势,为相关领域的研究提供有益参考。

搅拌摩擦增材制造的研究进展

介绍了基于搅拌摩擦焊原理开发的固相增材制造技术,根据制备工艺差异,搅拌摩擦增材制造技术可分为3类,分别为基于薄板逐层堆积的搅拌摩擦增材制造技术、消耗金属粉材的固相搅拌摩擦增材制造技术及消耗金属棒材的摩擦表面增材制造技术。对上述3类搅拌摩擦增材技术的国内外研究现状进行了介绍和分析,并对基于搅拌摩擦的固相增材制造技术未来的发展进行了展望。

搅拌摩擦增材制造技术研究现状与发展趋势

现有的高能束增材制造技术在成形大型高性能金属构件时存在适用材料范围有限、能源利用率低以及成形件各向异性等工艺特点,搅拌摩擦增材制造是近年来发展起来的一项新型固相增材制造技术,其无液态金属熔凝过程的成形特征为铝合金、镁合金等易氧化轻质合金的高性能快速制备提供了新的增材制造途径。文中首先指出现有高性能金属构件增材制造技术应用的局限性,重点介绍搅拌摩擦增材制造技术的工艺原理、性能优势及应用现状。综述了国内外所开展的主要搅拌摩擦增材制造技术现状,包括同轴送料式、预置料式等类别,进而展示了搅拌摩擦增材制造技术在轻质大型结构件增材制造及特征结构添加,梯度材料与涂层制备,缺陷损伤修复及新型复合材料制备等方面的应用潜力。最后,对搅拌摩擦增材制造技术的发展趋势进行了展望。通过文中综述,以期推动该技术在国内航空航天等领域大型轻质材料构件的制备方面实现应用。