Characteristics and printability of K417G nickel-base alloy powder prepared by VIGA method

Nickel-based K417G superalloy powder is the main material used in laser additive manufacturing (LAM) of aerospace engine turbine blades. In this study, K417G powder was prepared by the vacuum induction melting gas atomisation method (VIGA). Powder characteristics and microstructure were measured, and the properties of fabricated samples were studied. The results show that the powder mean particle size D₅₀ was 74?μm, flowability was 16.6?s/50?g, apparent density was 4.78?g?cm^–3, and the oxygen content of the powder was 0.015%. Powder and LAM sample microstructure consisted of γ, γ′, and carbide. The average microhardness was 410?HV, tensile strength was 1080?MPa, yield strength was 828?MPa and elongation was 13.52%. K417G superalloy powder prepared by VIGA method has potential for application in laser additive manufacturing.     

Preparation and printability of high performance 15Cr13MoY alloy steel powder for direct laser deposition

ABSTRACT

A novel 15Cr13MoY alloy steel powder used for direct laser deposition was produced using the vacuum induction gas atomisation (VIGA) method. The characteristics and laser printability of the 15Cr13MoY alloy steel powder were studied. The flowability of the spherical powder was 18.98?s/50?g^?1, and apparent density was 4.75?g?cm^?3. The fabricated 15Cr13MoY alloy steel samples composed of ferrite and bainite were prepared by DLD. The phases primarily consisted of a Fe–Cr–Mn solid solution M₇C₃, M₂₃C₆ and Y₂O₃. At the optimum laser power of 2200W, the average microhardness of 15Cr13MoY alloy steel sample was 350 HV, the tensile strength was 897?MPa, the yield strength was 704?MPa, the average elongation was 14.5%, and the product of strength and plasticity was 13.0?GPa%. The 15Cr13MoY alloy steel powder produced usingthe VIGA method had good powder characteristics and printability for fabricating the components produced by DLD.     

Microstructure and properties of ZrO2-reinforced 24CrNiMoY alloy steel prepared by selective laser melting

ABSTRACT

The process parameters of selective laser melting (SLM) fabricated 24CrNiMoY alloy steel were optimised. Different contents of zirconia powder were added to the 24CrNiMoY alloy steel powder. With the optimum process parameters, the fabricated samples were characterised using various modern analysis methods. The results show that the main phase composition of 24CrNiMoY alloy steel is proecctectoid ferrite (PF) and granular bainite (GB). After the addition of zirconia, Lath bainite (LB) begins to appear, and with the increase of zirconia, the content of LB first increases and then decreases. When the zirconia content is 0.3%, the average micro hardness of the 24CrNiMoY alloy steel reaches the maximum and is 374?HV. In addition, the tensile strength is 811?MPa, the elongation is 6.7%, and the fracture surface shows ductile fracture.     

3D打印用金属粉末的制备研究

针对国内3D打印用金属粉体材料的现状,通过对雾化喷嘴的设计改造,采用气雾化方法制备了304L不锈钢粉末;并通过扫描电镜、激光粒度测量仪以及霍尔流量计等对粉末的颗粒形貌、粒度分布、流动性等进行了观察研究。结果表明:采用自制双层雾化喷嘴制备的合金粉末,球形度高,粒度分布范围窄,粉末平均粒径为40μm,符合3D打印对金属粉体材料的要求。     

Effect of powder oxygen content on the microstructure and properties of Co–Cr dental alloys fabricated by selective laser melting

A high oxygen content can lead to metallurgical defects such as holes and microcracks in the products of selective laser melting (SLM) that significantly reduce the density and mechanical properties of a denture. In this study, a batch of a Co–Cr alloy powder was subjected to forced oxidation. SLM was used to prepare specimens from the powder before and after the treatment for the performance tests. The results showed that Co–Cr alloy powders with oxygen contents 184 and 616?ppm could both achieve good shaping of the specimens under identical SLM conditions. There was no significant difference between the specimens in terms of fuselage morphology, microstructure, density, tensile strength, yield strength and hardness. However, the elongation of the alloy synthesised using the higher oxygen content powder was significantly lowered, but still higher than that required by the ASTM F75 Casting Standard of the United States.     

紧耦合气雾化技术制备选区激光熔化用18Ni300合金粉末的研究

基于紧耦合气雾化技术制备符合选区激光熔化用18Ni300合金粉末, 重点研究了雾化压力对粉末粒度(中值粒径, D₅₀)、粒度分布、球形度、氧含量、流动性和松装密度等特性的影响。结果表明: 雾化压力对上述粉末特性影响显著, 当雾化压力在3.5 MPa到4.5 MPa范围时, 随着压力的提高, 粉末粒度降低、表面形貌改善、流动性变好、松装密度增加。当雾化压力为4.5 MPa时, 所制备的粉末综合特性最优, 粉末粒度(D₅₀)为34 μm, 球形度为0.77, 氧含量为0.02%(质量分数), 流动性为17.4[s·(50g)-1], 松装密度为4.32g·cm-3, 15~53 μm粒径范围粉末收得率为38.1%, 满足选区激光熔化技术对金属粉末性能的要求。     

制粉方法对Inconel718合金粉末组织和性能的影响

以Inconel718合金为研究对象，分别采用等离子旋转电极法（PREP）和气体雾化法（VIGA）制备了金属球形粉末，研究了不同制粉方法对粉末在热处理前后的组织和成分分布的影响，采用对流热交换原理对两种制粉方法对应的冷速进行了模拟计算。分析结果表明：采用PERP法制备的Inconel718合金粉末在氧增量、球形度及流动性方面具有一定的优势，而VIGA法制备粉末有利于提高粉末的显微硬度、细粉粒径；两种粉末经过相同的热处理工艺后，其组织变化规律相同，均析出富Nb和Mo相。模拟计算结果表明：VIGA法制备细粒径粉末的冷速明显高于PREP法对应的粉末，与实验对应的性能数据结果相吻合。     

金属粉末特性对选区激光熔化工艺及其制件性能影响

高品质金属粉末是选区激光熔化（selective laser melting,SLM）制备高性能制件的重要基础。粉体特性对选区激光熔化技术的影响及其机理研究是理解选区激光熔化技术不可或缺的重要组成部分。本文从粉末物理和化学特性出发,论述了粉末特性对选区激光熔化工艺、制件微观组织与性能的影响。结果表明,粉末的物理特性,尤其是粉末形貌和粉末粒度分布能显著影响其流动性和粉末床堆密度等关键工艺特性;而粉末的化学成分,特别是杂质成分,是影响制件相组成和微观组织的重要因素。在此基础上,本文进一步介绍了选区激光熔化过程中高能量源与粉末颗粒的冶金作用机理研究进展。     

选区激光熔化工艺参数对气雾化316L不锈钢粉末成形制品性能的影响

本研究系统考察了激光功率和扫描速度对316L不锈钢粉末选区激光熔化工艺成形熔道、制品微观组织及力学性能的影响,并分析了各类缺陷的形成原因。研究结果表明:在低激光功率和高扫描速度条件下,熔道中出现了大量球状颗粒,这些颗粒之间的空隙恶化了下一层粉末的熔化条件,这正是成形制品中熔道分布混乱以及孔洞、裂纹产生的根本原因,进而导致成形制品力学性能降低;在高激光功率和低扫描速度条件下,熔池快速升温/冷却的热应力作用增强,使得成形制品的熔道交界处也存在孔洞和裂纹等缺陷。在本研究实验条件下,激光功率为350 W,扫描速度为1750 mm/s时,SLM成形制品的力学性能最为优异,其中抗拉强度为731 MPa、屈服强度为638 MPa、断后伸长率为40.0%,致密度为96.27%。     

航空航天用高品质3D打印金属粉末的研究与应用

作为金属3D打印的主要耗材,金属粉末对打印产品的质量有着至关重要的影响,航空航天、国防、医疗等领域精密复杂零件的3D打印对粉末性能,如粒度、形貌和纯净度等有着较高的要求。研究并介绍了航空航天领域3D打印用高品质镍基、钴基合金及钛合金等金属粉末的基本要求及主要制粉工艺;对两种常用的高质量金属粉末制备工艺真空感应熔炼氩气雾化法(VIGA)和等离子旋转电极法(PREP)进行了比较,指出VIGA法细粉收得率高,但存在空心粉和卫星粉;PREP粉球形度高、表面光洁、粉末粒度分布窄、流动性好、陶瓷夹杂少,在金属3D打印领域具有独特的优势。为进一步提高PREP粉的质量,应开发更新一代等离子旋转电极雾化制粉技术及装备,提高细粉收得率和生产效率。     

气雾化压力对3D打印用316L不锈钢粉末性能的影响

采用真空熔炼气雾化工艺制备3D打印用316L不锈钢粉末,通过调整雾化参数,研究了不同雾化压力对粉末化学成分、粒度分布、球形度、表面形貌、流动性及松装密度等特性的影响。结果表明:在保温温度(1560±20)℃、保温时间20 min、漏包温度(1050±30)℃、高纯氮气雾化及雾化压力3.0 MPa工艺参数下,制备得到的粉末性能可达到氧含量(质量分数)0.08%、中位径31.39μm、球形度0.75、流动性21.56 g/(50 s)及松装密度3.88 g/cm~3,基本满足不同金属3D打印技术对粉末材料性能的要求。     

稀土Y对气雾化制备PH13-8Mo钢粉末特性的影响

摘要：研究了不同含量的稀土Y对选区激光熔化技术(SLM)用PH13 8Mo钢粉末特性的影响，并通过Thermo-Calc热力学软件、粉体综合特性测试仪、霍尔流速计、激光粒度分析仪、扫描电镜和电子探针等方法对不同Y含量的PH13-8Mo钢粉末特性的变化规律进行研究。结果表明，随着金属粉末中Y含量的增加，金属粉末的松装密度从3.73提高到3.93g/cm3，50g粉末的自由流动时间从25.44减小到25.11s，粉末的流动性变好。同时，PH13 8Mo钢粉末的平均粒径从37.29减小到30.99μm，粉末的粒度分布区间变窄。研究还发现，不含Y的PH13-8Mo钢粉末的组织由树枝晶和等轴晶组成，而Y质量分数为0.080%的PH13 8Mo钢粉末的组织均由等轴晶组成。综上，在PH13.8Mo钢粉末中加入稀土Y，粉末的特性得到优化。     

Metallurgical and mechanical characterisation of titanium based materials for endosseous applications obtained by selective laser melting

Abstract

The aim of the present work was to estimate the feasibility of selective laser melting (SLM) to produce Ti-hydroxyapatite bioactive composite materials for personalised endosseous implants. Mixtures of Ti6Al7Nb surface conditioned powder with hydroxyapatite up to 5 vol.-% were processed by SLM with the same scanning strategy and laser power in the range of 50–200 W. Specimens with porous structures were characterised from a structural and mechanical point of view. Irrespective to the initial hydroxyapatite content, density increased by increasing the laser power. The microstructure of manufactured parts mainly consisted of α′ martensite. In materials with 5 vol.-% hydroxyapatite, a phosphorous containing phase formed as a consequence of hydroxyapatite decomposition and interaction with the base Ti alloy. By increasing the laser power, the tensile strength increased mainly due to the density improvement of all the investigated materials.     

选区激光熔化铝合金制备研究现状

选区激光熔化（selective laser melting,SLM）技术因具有可定制化、加工周期短及精度高等特点,在工业生产中得到广泛应用。本文对选区激光熔化技术及其在铝合金及铝基复合材料制备的研究现状进行了综合性论述。通过论述选区激光熔化特性引出选区激光熔化打印铝合金的优势。介绍了适用于选区激光熔化技术的铸造Al?Si系合金,结合扫描策略和工艺参数优化,探究了选区激光熔化铝硅合金的微观结构、相组成和力学性能变化规律。讨论了选区激光熔化微/纳米陶瓷强化铝基复合材料的研究现状,分析与总结了添加强化颗粒对组织结构、相对密度、润湿性及相应力学性能的强化机理。总结了工业界与学术界关注的新型高强度铝合金材料的开发及其选区激光熔化的制备,重点论述了新型铝合金的固溶强化和析出相强化机理,并分析了对相对密度和力学性能的影响因素。最后对选区激光熔化铝合金发展趋势及现阶段存在的问题进行了展望。     

Fatigue strength of a Ti–6Al–4V alloy produced by selective laser melting

The fatigue properties and the fracture mechanisms of the Ti–6Al–4V alloy produced by selective laser melting (SLM) from a powder of an CL41TiELI titanium alloy have been studied. Cylindrical blanks were grown at angles of 90° and 45° to a platform. The best fatigue strength is observed in the samples the blanks of which were grown at an angle of 45°. It is found that the structure of the SLM material can contain portions with unmelted powder particles, which are the places of initiation of fatigue cracks.     

Selective Laser Melting of Maraging Steels Using Recycled Powders: A Comprehensive Microstructural and Mechanical Investigation

Selective laser melting (SLM) is an additive manufacturing (AM) technique designed to use a high energy density laser to fuse metallic powders for producing three-dimensional parts. So far, most studies of SLM have been focused on using virgin metal powders. There are few comprehensive studies on the microstructure and mechanical properties of SLM-produced parts using recycled powders, especially for maraging steels. In this study, we employ recycled steel powder (reused after 113 building cycles) in the SLM process to print multiple shaped components and systematically characterize the microstructure and mechanical properties (indentation, tensile, and Charpy testing). Our results show that maraging steel produced with recycled powder exhibit the nearly identical microstructure and mechanical properties (940 MPa yield strength, 1127 MPa ultimate tensile strength, 11 pct elongation, and 47.5 J room temperature impact fracture energy) to those produced using virgin powders. This study provides a useful generic guide towards using recycled metal powders in the SLM processing, promoting an economic solution to industrial productions.

     

Effect of subsequent Hot Isostatic Pressing on mechanical properties of ASTM F75 alloy produced by Selective Laser Melting

Abstract

The Co-based alloy ASTM (Co – 28.5?wt.-% Cr – 6.3?wt.-% Mo) is widely used for medical implants, e.g. knee prostheses, and is commonly processed by investment casting. Selective laser (SLM) melting is supposed to be an efficient alternative for the production of individually designed knee implants regarding production time and production costs. The mechanical properties, in particular the fatigue strength, of the material have been studied in different states of the material. The mechanical properties of investment casted ASTM F75 and PM-SLM produced ASTM F75 were investigated. The focus in this study was on the PM-SLM material, the specimens were initially produced by selective laser melting and a part of the specimens were further processed by hot isostatic pressing (HIP). The PM-SLM material was mechanically tested in the as-SLM state as well as in the SLM+HIP state. It was found that the mechanical properties of the as-SLM material did not reach the level of the fatigue strength of as cast material. The post-densification treatment by HIP offers distinct improvements regarding the fatigue strength compared to the as-SLM material.     

增材制造用高温合金粉末制备技术及研究进展

球形粉末是增材制造、粉末冶金、注射成型等制备工艺的重要原料,其成分、粒度、球形度、空心粉率等是影响最终构件性能的关键因素。本文详细介绍了真空感应熔炼气雾化法、电极感应熔炼气雾化法以及等离子旋转电极雾化法等三种可用于增材制造的工程化高温合金球形粉末的制备技术,分析了这三种制粉工艺的特点,阐述了这三种制粉工艺的研发进展,探讨了三种制粉工艺所制备的粉末缺陷形成原因及控制方法,并提出了增材制造用高温合金粉末制备技术的发展趋势。     

选择性激光熔化成形CoCrWMo合金工艺优化及摩擦磨损性能

对选择性激光熔化成形CoCrWMo合金的工艺参数进行优化,并对最佳工艺下合金试样的摩擦磨损性能进行分析。结果表明:选择性激光熔化最佳工艺参数为激光功率280 W,扫描速度800 mm?s?1,铺粉层厚0.03 mm,扫描间距0.10 mm,扫描策略为旋转扫描法（层与层之间旋转15°）。该工艺下激光体能量密度为117 J?mm?3,试样相对密度为99.4%,上表面粗糙度（Ra）为4.98 μm,显微硬度为HV 386,抗拉强度为984 MPa,屈服强度为663 MPa,断后伸长率为12.9%。在干摩擦下,CoCrWMo合金的平均摩擦系数随施加载荷的增加呈下降趋势;受磨损过程中应变诱导马氏体转变的影响,合金平均磨损率呈现先增高后降低的变化规律,主要磨损机制为磨粒磨损和粘着磨损。     

选区激光熔化成形TA1钛合金组织性能研究

通过选区激光熔化(SLM)制备TA1合金,研究了打印态及退火态TA1合金的组织及性能。研究结果表明,SLM制备的TA1合金具有优异的力学性能,其抗拉强度、伸长率及断面收缩率均满足GJB 2744A-2007中锻件的要求,尤其抗拉强度达到600 MPa以上。打印件在不同打印方向上的性能略有差异,Y方向上最优,X方向上次之,Z方向上最弱(580 MPa)。退火处理后的组织更加均匀,抗拉强度、断面收缩率和硬度比打印态略有降低,伸长率略有增大。SLM制备的TA1合金能够在复杂精密件的应用上代替锻件,节省原材料,为3D打印TA1合金的应用提供参考。