结构材料喷射成形技术与雾化沉积高温合金

喷射成形是利用快速凝固方法直接制备金属材料坯料或半成品的先进材料制造技术 ,喷射沉积高温结构材料的冶金性能好、生产效率高、成本低 ,因而在近几年得到了迅速发展 .本项研究的主要目的是要通过喷射成形工艺参数的调整、最大限度地直接减少喷射成形坯中的孔隙度 ,进而得到优质坯料 .利用优化的雾化喷射沉积技术制备了多种高温合金沉积坯 ,沉积坯整体致密、晶粒细小、组织均匀、无宏观偏析、含气量低、力学性能提高 .还简要地比较了喷射成形高温合金与用常规铸锭冶金工艺和粉末冶金工艺制备高温合金的异同 ;总结了航空材料研究院喷射成形高温材料近年来的研究状况 ,包括专用高温材料喷射成形装置和技术及其应用 .     

喷射成形技术及其在钢铁材料上的应用

喷射成形是近年来发展非常迅速的一种近终成形先进冶金工艺技术。与传统铸造工艺及粉末冶金工艺相比,喷射成形设备、工艺简单,能生产偏析小、晶粒细、致密度高的材料。喷射成形技术在铝基合金、铁基合金、高温合金、铜合金及复合材料等方面都得到了广泛的应用。主要介绍该技术的原理及其在钢铁材料方面的应用情况,并讨论了它在钢铁领域的发展趋势,指出喷射成形工艺是一种有望替代粉末冶金工艺生产高合金钢材及一些特殊钢材的崭新工艺。     

A hybrid arc spray forming technique for the manufacture of nickel superalloy IN617

Spray forming produces cast microstructures with comparatively low macro‐ and micro‐structural chemical segregation and is thus well‐suited for the manufacture of complex chemistry, multi‐component alloys that otherwise show strong elemental segregation. Although spray formed Ni superalloys have shown properties equivalent or superior to their conventionally cast/wrought counterparts, they have not been adopted commercially because of the difficulties in ensuring a high process yield and the complexity and associated cost of large‐scale Ni superalloy melting. In this paper, we describe a hybrid arc spray forming (HASF) process in which costly, large‐scale alloy melting as pre‐cursor to spray forming is avoided by the use of a consumable wire feedstock. To achieve thermal conditions of melt spray forming – essential to produce a refined, polygonal grain structure – a customised secondary atomisation system has been developed. Fe‐0.8 wt%C and Ni superalloy IN617 microstructures and preliminary mechanical properties suggested that hybrid arc spray forming may offer an attractive combination of convenience, low cost and mechanical performance.     

Spray forming of aluminum alloys and its composites: an overview

In this article, the work that has been carried out in the area of spray forming of aluminum alloys and its composites has been summarized. The developments that had taken place in the past two decades in this area have been presented. Most of the researchers have investigated on the microstructural properties of these alloys and their composites. In this article, main emphasis was given to the microstructures, wear characteristics, and mechanical properties of as-cast and as-sprayed aluminum alloys. Also, this article is designed to provide the microstructures of as-cast and as-sprayed aluminum-15% silicon alloy. The microstructure of as-sprayed alloy has invariably indicated equiaxed grains throughout the deposit and has been observed that the Si particles are uniformly distributed in the Al matrix. Spray forming offers a combination of low cost manufacturing with enhanced properties and performance. As such it has emerged as a key competitor for existing technologies such as conventional casting, ingot metallurgy, and powder metallurgy.     

喷射成形镍基高温合金的研究进展

喷射成形是一种新型快速凝固技术,采用这项技术制备的镍基合金,具有细小,球状的晶粒和均一的组织,从而提高其性能,综述了喷射成形镍基高温合金的发展概况及组织,性能特点。     

粉末短流程成形固结技术的研究及展望

针对粉末冶金行业最新发展的几种短流程成形固结新技术,结合华南理工大学近十多年来在粉末材料-工艺-装备-零件一体化方面开展的研究,重点阐述了粉末冶金温压成形、高速压制成形、喷射成形、多场作用下粉末成形与烧结一体化技术的研究进展及应用情况。指出在粉末冶金成形固结研究领域,合理拓展现有粉末冶金技术规范的空间,有望给传统粉末冶金成形固结技术注入新的活力。粉末冶金成形固结新技术的不断出现,必将促进先进制造业和高技术产业的快速发展,也必将给材料工程和制造业带来更加光明的前景。     

Spray Forming of Homogeneous 20MnCr5 Steel of Low Distortion Potential

Spray forming is an advanced technology for the manufacture of homogeneous material from the melt. In this study, 20MnCr5 steel, a typical case hardening steel for gear and shaft production, has been spray formed and hot worked to semi‐finished bars. Shaft‐like specimens have been made from the spray‐formed material for distortion investigation. Material characteristics of the spray‐formed 20MnCr5 steel have been studied. In cooperation with other projects of the Collaborative Research Center SFB570 ‘’Distortion Engineering’’, evaluation of distortion behavior of the shaft specimens after machining and heat treatment has been made in comparison with continuous cast material. Spray‐formed 20MnCr5 steel shows lower distortion potential due to improved material homogeneity.     

Analysis of spray formed tool steels

The technique of atomising liquid metal and compacting the micro‐droplets to a billet on a rotating support combines advantages from cast, wrought and powder metallurgical materials. A production rate of several tons per hour requires precisely controlled processing routines. Important process parameters based on processing, manufacturing and application of spray formed material are now developed by fundamental investigations established in projects focused in a special co‐operative research program (SFB 372) at the University of Bremen which is funded by the Deutsche Forschungsgemeinschaft (DFG). By this method advanced alloys of high hardness can be formed without inhomogeneities like segregations and pores in the center of the ingot. By example of tool steels the influence of spray forming on microstructure and homogeneity of the elemental distribution is shown.     

TiAl合金精密成形技术发展现状及展望

TiAl合金是一种优异的轻质耐高温结构材料,在航空、航天、汽车、兵器等热端部件制造领域具有广阔的应用和发展前景,但其较低的室温塑性、韧性和较差的冷/热加工性能,限制了其工程化的进程.为挖掘TiAl合金的应用潜力,国内外研究机构和企业从材料设计、组织性能调控到成形工艺等方面开展了卓有成效的研究.总结了近年来国内外在TiA...     

The effect of spray forming on the microstructure and properties of a high chromium white cast iron

The effect of spray forming on the structure and properties of a 17% Cr, 2.5% C white cast iron is described and compared with conventionally cast material of the same composition. Spray forming resulted in a substantial reduction in microstructural scale (eutectic (Cr,Fe)₇C₃ fields of up to 500 m in conventionally cast material were replaced by discrete carbides of typically 2–8 m diameter in the spray cast deposit). Carbide size varied as a function of position in the spray deposit, being approximately twice the size at mid section compared with either surface or interface with the collector. Carbide size was not altered by the gas to metal ratio used to atomise the spray. Spray forming increased transverse rupture stress and work of fracture by 50% compared with the conventionally cast material. Forging of the spray formed material was possible at 950°C, without inducing carbide fracture or void formation in the matrix. Quenching into iced water from 300°C induced extensive macroscopic cracking in the conventionally cast material whereas 400°C was required in the spray cast material to induce similar damage. The relationship between processing, microstructure and mechanical properties is discussed.     

机械合金化和粉末冶金法制备Fe-Mn-Si基形状记忆合金的研究进展

铁基形状记忆合金由于价格低廉、强度高、加工性能好、可焊接等优点引起广泛重视。机械合金化(MA)和粉末冶金(PM)作为制备材料的新工艺,可以用来制备性能优越的形状记忆合金。本文详述了机械合金化和粉末冶金工艺在制备Fe-Mn-Si基形状记忆合金过程中对合金相变、组织与性能的影响,以及此类合金在新领域的应用。最后提出了现阶段在研究MA/PM工艺制备Fe-Mn-Si基SMA中有关工艺参数、相变机制以及回复应力和低温应力松弛所存在的问题。     

难变形材料热静液挤压复合精密塑性成形工艺

目的 研究热静液挤压及其复合塑性变形工艺在高密度钨合金、钨铜合金、钛基复合材料及镁合金薄壁细管等难变形材料方面的制备。方法 通过对高密度钨合金难变形材料进行热静液挤压及旋转锻造等塑性成形,分析了材料在成形过程中的微观组织及性能变化规律和强化机制,制备出大长径比穿甲弹弹芯材料。在此基础上,将该复合塑性变形技术拓展至两相不互溶材料钨铜合金、钛基复合材料及大长径比镁合金毛细管等难变形材料方面的制备。结果 热静液挤压及其复合塑性变形工艺在粉末冶金难变形材料的致密化方面具有显著优势,获得材料不仅致密度高,而且有效实现了控形控性;对于镁合金薄壁细管成形而言,也可以实现组织与性能的有效调配,同时材料的精度较高。结论 热静液挤压及其复合塑性变形工艺在难变形材料的制备与成形方面具有独特的优势与广阔的应用前景。     

Microstructure and elevated temperature mechanical properties of Al–8Fe–4RE alloy fabricated by spray forming

Al–8Fe–4Ce alloy is currently manufactured by consolidating the atomized powders. With the aim to reduce the cost, spray forming process was applied in manufacturing with misch metal as raw materials. Spray forming (SF) as well as casting were employed to prepare Al–8Fe–4RE alloy, followed by hot‐press to compact the samples. The mechanical properties of SFed and cast Al–8Fe–4RE alloys are characterized at a temperature of 350 °C. The results show that the Al₃Fe phases contained in SF alloy is comparatively refined, forming needle‐shaped phases embedded in the Al matrix, and the SF alloy also showed lower degree of preferred orientation in (111) plane. Although both factors might explain the superior performance of the SF sample, the fracture appearance after tensile test at 350 °C shows that the contribution from crystallographic feature might be predominant. Spray forming is proved to be a very promising technique for manufacture of Al–Fe–Ce alloys of high strength at an elevated temperature.     

Spray forming: Science and technology

Spray forming involves sequential gas atomization of a melt into a spray of fine droplets and their deposition on a substrate to build up a high-density preform. The rapid solidification inherent in spray deposition generates refined, equiaxed and low segregation microstructures. A number of promising features of this near-net shape manufacturing process are highlighted and compared, wherever possible, with the conventional casting and PM techniques. Some commercial nozzles used to create spray and mechanisms associated with spray generation are described. The consolidation of the droplets and the development of the microstructure in the deposit are primarily governed by the nature of the spray and the thermal state of droplets on the deposition surface. Several microstructural characteristics of the deposit are presented and their origin in spray deposition is discussed.     

粉末冶金曲轴主轴承盖的研制

分析了汽车发动机曲轴主轴承盖473QB的结构和性能特点,采用粉末冶金材料取代铸铁或球墨铸铁,降低了生产成本。制定了合理的开发方案,确定了材料配方、生产工艺流程,并设计了模具。通过试制进行产品金相分析,改进了粉末冶金工艺和模具结构,成功研制出了符合要求的可承受复杂载荷的粉末冶金曲轴主轴承盖。     

直升机轮毂材料用喷射成形7055铝合金性能

目的 研究一种新型直升机轮毂用材料。方法 采用喷射成形工艺制备了7055铝合金轮毂,与传统2A14铝合金材料对比分析,分析了其组织结构（晶向结构、致密度等）、宏观性能（抗拉强度、屈服强度等）、静压试验以及L-T方向断裂韧性等。结果 喷射成形7055铝合金组织为细小的等轴晶组织,合金相均匀弥散分布,无宏观偏析、疏松、孔洞等铸造缺陷,其抗拉强度比传统2A14铝合金高出33.3%,承载能力高出39.4%。结论 喷射成形7055铝合金,可有效替代2A14等传统直升机轮毂材料,改善轮毂的稳定性和安全性,推进轮毂材料的国际化水平。     

冷气动力喷涂技术研究进展

作为一种新的涂层方法－冷气动力喷涂因能在较低的温度下喷涂金属、合金以及复合涂层而受到人们的关注。综述了国内外冷气动力喷涂技术领域的最新研究进展，主要包括冷气动力喷涂技术研究、冷喷涂涂层的结构性能和涂层特点及其应用。     

Microstructures and tensile properties of spray-deposited high-strength aluminium alloys

Spray deposition is a new rapid solidification technique which produces bulk preforms directly from the melt metals. A spray deposition process was used to develop several high-strength aluminium alloys based on their commercial chemical compositions. These alloys include 2024 alloy, 7075 alloy and 7075 alloy modified with 1.0% Fe and 1.0% Ni.The deposits possessed rapid solidification microstructure with grain size of about 20 μm and a relative density of over 94%. The hardening phases of the materials in T4 or T6 conditions consisted of supersatured solid solution, stable and unstable ageing precipitates and disperse phases. The formation of the fine distributed disperse phases was due to the addition of iron and nickel to the 7075 alloy. The spray-deposited materials exhibited substantial improvement in tensile strengths and maintained acceptable ductility when compared to the corresponding ingot metallurgy processed materials. This revised version was published online in November 2006 with corrections to the Cover Date.     

低黏结剂含量SiC素坯的选区激光烧结

Al/SiC是SiC基复合材料, 具有优异的力学性能和热学性能, 在大功率电子器件、5G基站关键冷却组件、电动汽车、高速刹车片、空间探测器操作装置等相关领域具有不可替代的作用。传统制备工艺的局限性使得近净成形的无压浸渗法成为制备Al/SiC复合材料的一种较好的方法。得到高质量的碳化硅(SiC)陶瓷素坯是熔渗技术的先决条件, 选区激光烧结技术是获得高质量陶瓷素坯的一种新方法。该方法具有快速、高效的优点, 无需模具即可成型制备大规模、复杂形状部件。本研究以热塑性酚醛树脂为黏结剂, 利用机械混合与喷雾造粒的方法制备了复合粉体, 采用选区激光烧结技术制备SiC素坯, 制备了黏结剂体积分数低至15%的样品, 并对其力学性能和微观结构进行表征。当树脂含量增大到体积分数25%时, SiC坯体的强度增量为702.1%。对于喷雾造粒粉体制备的样品而言, 喷雾干粉的多孔结构使得SiC生坯的孔隙率较高(71.18%), 导致生坯强度下降。     

NET SHAPE MANUFACTURING - THE UTILITY OF POWDER METALLURGY PROCESSING

Powder metallurgy is a source of new and viable near or net shape manufacturing processes, with compelling economic and technical advantages over conventional ingot metallurgy practice. Selected commercial methods are considered, namely pressing and sintering, injection molding, powder preform working and direct powder consolidation. Particular attention is directed to the prevailing state of stress, temperature and time in each mode, since these dictate densification mechanism(s), and hence microstructure and properties.