粉末冶金工具钢生产的新发展

简述了全球及Ｂ¨ｏｈｌｅｒＵｄｄｅｌｈｏｌｍ 集团最近的粉末冶金工具钢的销售量，重点介绍了ＢＵ 集团目前投巨资建立的整套的粉末冶金工具钢生产线所采用的先进技术。     

THE FABRICATION OF HIGH-SPEED TOOL STEEL BY ULTRAFINE POWDER METALLURGY

Abstract

Various powder-metallurgy techniques have been developed during recent years to avoid segregation effects associated with the conventional methods of casting and forming high-speed steels. These techniques have generally involved the consolidation of hot working or hot pressing of 50–500μm prealloyed powders into dense billets or rods.

The work described has demonstrated that much finer, 0·5–5μm, powders of M2 and M50 steels may be cold pressed and sintered to produce bodies with densities of 99% theoretical containing uniformly distributed 1–2μm particles of carbides. It is anticipated that the method will have application for the manufacture of complex-shaped parts with very small material losses and little machining.

An account is given of the preparation of the fine powders by ball-milling and their subsequent compaction, sintering, and microstructure. The control of carbon and oxygen levels by carbon addition to the powders is described.     

粉末冶金高氮不锈钢的研究与发展现状

本文介绍了高氮不锈钢的优点及制造方法,总结了粉末冶金高氮不锈钢的制粉及成形方法.介绍了粉末冶金高氮不锈钢的应用领域及前景.     

粉末冶金法制备医用多孔钛的研究

本文以碳酸氢铵做造孔剂,采用粉末冶金法制备出多孔钛.研究了烧结温度对多孔钛显微形貌、显气孔率、抗压强度的影响.研究表明,提高烧结温度,有利于Ti晶体的发育,并提高制品的抗压强度.系统研究了碳酸氢铵加入量对多孔钛显气孔率的定量影响.在同一烧结温度下,随着造孔剂含量的增加,试样的显气孔率提高;添加相同含量的造孔剂,随着烧结温度的提高,试样的显气孔率降低.提出将坯体烧结过程中的收缩看作碳酸氢铵留下孔的收缩和钛粉收缩的观点,得出显气孔率的倒数和钛与碳酸氢铵质量分数成一次函数关系的结论.     

THE PROPERTIES OF PLATINUM-COBALT MAGNETS PRODUCED BY POWDER METALLURGY

Abstract

Improved and more consistent magnetic properties can be obtained from platinum-cobalt alloys produced by powder-metallurgy techniques. The importance of heat-treatment is emphasized, and for optimum permanent-magnet properties it is shown that the equiatomic stoichiometric alloy should be employed. Magnetic measurements demonstrate that energy products < 10 × 10⁶ gauss-Oe, and coercive forces up to 4900 Oe can be achieved.     

采用氢化钛粉制备Ti-6Al-4V合金

研究了以氢化钛粉和Al-V合金粉为原料，采用粉末冶金方法，在真空炉中脱氢烧结一次完成的生产工艺，制备了Ti-6Al-4V合金．其合金性能为：烧结密度4．4g／cm^3，抗拉强度854．89MPa，延伸率3.8％，达到国外相同水平．该方法简化了钛粉制备工艺，有利于降低最终产品杂质含量和节能．     

THE POWDER METALLURGY OF RUTHENIUM

Abstract

An investigation of the powder metallurgy of ruthenium is described, from the reduction of ammonium ruthenium chloride to the working of sintered compacts. The powder properties measured were specific surface area, by a simplified BET method, and tap density. The dependence of these properties on the conditions of reduction has been determined. The surface area of powders varies from 1 to 10 m²/g in the temperature-of-reduction range 700-350°C. The tap density is also variable (1–3 g/c.c.) and is generally related to the surface area. The effects of compacting pressure and temperature on sintering are described, the progress of sintering being observed by measurements of the “open” and “closed” porosity present in samples. Compact densities up to 95% of theoretical can be obtained by sintering at 1500°C. The selection of powder properties and compacting pressures to be used in the production, by vacuum sintering at 1500°C, of high-density compacts for working, is governed by the necessity to maintain open porosity during the heating cycle up to at least 1200°C, as considerable gas evolution occurs at this temperature; at the same time it is essential that good densification shall have occurred even at this stage. These conditions can be met by using powder with a surface area of 2–5 m²/g and compacting pressures in the range 0·5–25 tons/in ².

Observations on the hot working of sintered compacts indicate that ease of working is related to the surface area of the powder.     

SOME EXPERIMENTS IN THE PRODUCTION OF LOW-ALLOY STEEL BY POWDER METALLURGY

Abstract

The properties of alloy steels produced by powder-metallurgy techniques, as compared with those of conventional cast or wrought alloy steels, are reviewed. Factors affecting the production of alloy steels by powder-metallurgy techniques are enumerated, and the importance of adequate mechanical properties coupled with ease of processing is emphasized. The paper covers the preparation and testing of a wide range of low-alloy steels including copper steels, nickel steels, and complex steels; these being made up either from elemental powders or from pre-alloyed or complex powders. The influence of various alloying elements upon the mechanical properties of the steels produced is indicated, and the merits of the various compositions investigated, are discussed.

The response of powder-metallurgy alloy steels to quenching is next determined, and the effects of the elements carbon, manganese, nickel, copper, and molybdenum upon the hardcnability of alloy steels is summarized in the form of depth-hardening curves. The use of precipitation-hardening as a means of improving the properties of low-alloy steels is also investigated for a wide range of copper-containing steels. It is demonstrated that by employing this technique it is possible to obtain very significant improvements in properties, together with some processing advantages.     

PROPERTIES OF ALUMINIUM-TIN ALLOYS PRODUCED BY POWDER METALLURGY

Abstract

Aluminium-tin powder-metallurgy alloys containing 20–40% Sn and 0–3% Cu were prepared by compaction and extrusion of prealloyed atomized powder. The powder-metallurgy (PM) material had a fine distribution of the tin phase and was stronger, with greater fatigue strength than an Al-20% Sn-1 % Cu cast alloy but was harder and less ductile. Heat-treatment reduced the hardness of the PM alloys to values comparable with those of the cast material, whereas the strength, although also reduced, remained superior to that of the cast product.     

粉末冶金生产工艺的两大发展

粉末冶金是节能、高效、环境友好、适合大批量生产的金属成形工艺,又因其工艺特点,创造了一系列特殊性能和用途的新材,有着广阔的发展前景.但是传统粉末冶金工艺制备的材料均含有残余孔隙,影响了性能的提高,其生产的零件的形状复杂性也受到限制.以粉末冶金高速工具钢为代表的完全致密化工艺是粉末冶金生产工艺的一大发展,粉末注射成形则是...     

PROPERTIES OF MARAGING STEEL 300 PRODUCED BY POWDER METALLURGY

Abstract

Powders of 300-grade maraging steel have been produced by two different atomizing processes and consolidated by hot isostatic pressing, extrusion, hot rolling, or a combination of these methods. The tensile properties of the PM alloys were equivalent or superior to those of the conventionally cast and forged alloys, but no improvement in fatigue and fracture-toughness properties was gained. Fine grain sizes (1–5 μm) were obtained by hot rolling either conventionally processed or PM bars of grade-300 maraging steel at 760, 820, and 870°C, followed by air-cooling. In all cases, the tensile properties and fracture toughness were improved by grain-size refinement.     

THE PREPARATION OF BERYLLIUM MAGNESIUM ALLOYS BY POWDER METALLURGICAL METHODS

Abstract

The preparation of alloys of beryllium and magnesium containing up to 20 wt.-% magnesium is described. Dense bodies may be prepared by infiltration of beryllium skeletons with molten magnesium or by liquid-phase sintering of cold-compacted mixed elemental powders. Such alloys consist of the appropriate element together with the compound MgBe₁₃, usually present as a continuous intergranular phase.     

SOME PROBLEMS IN THE POWDER METALLURGY OF TITANIUM

Abstract

An investigation is described of problems encountered in the conventional powder metallurgy of titanium, with particular reference to the pressing and sintering characteristics of titanium and titanium hydride powders and to sources of contamination. It is concluded that, for success to be achieved in the production of fully dense sintered material by the present method without incurring serious contamination, commercial titanium would have to be available as powder conforming to strict purity requirements.     

机械合金化制取Ni－Fe－Mo粉

机械合金化可使在室温下部分互溶体系Ｎｉ－Ｆｅ－Ｍｏ形成ｆｃｃ固溶态粉末，Ｎｉ、Ｆｅ、Ｍｏ三种元素在粉末颗粒表面及内部均匀分布存在，固溶态粉末的液相生成温度的为１７１０Ｋ。     

喷雾法制备活塞环用MP43喷镀合金钼粉

分析了喷雾法制备活塞环用MP43喷镀合金钼粉的生产过程。过程中选择含三氧化二硼的氧化硅纳米胶为粘接相，混合金属粉体（钼、镍、铬）与粘接相组成的粉浆为分散体，经离心式雾化器分散并热空气干燥以及焙烧和烧结等热处理过程而生产合金喷镀钼粉。分析结果表明，选择混合金属粉体为制粒材料符合经济性原则；选择含三氧化二硼的氧化硅纳米胶为粘接相符合晶界细化原则。选择喷雾干燥制粒和热处理相结合的过程，能够生产出流动性和粒度分布满足等离子喷镀工艺要求的喷镀合金钼粉产品。     

铁基粉末冶金齿轮泵侧板摩擦学性能研究

本文研究了铁基粉末冶金材料的摩擦学性能,研究结果表明:硫化铁基粉末冶金材料基体中均匀分布着软质FeS相,改善了材料的摩擦学性能,实际铁基材料侧板的极限载荷是25MPa,达到高压齿轮泵的工作要求。     

微波辅助增强化学还原法制备超细铜粉

微波辅助化学还原法是一种联合法.本文介绍了采用这种方法制备超细铜粉的工艺过程及条件.研究了微波功率,反应物浓度与产物收率的关系,并对超细铜粉抗氧化性问题进行了探讨.     

粉末冶金高氮不锈钢的研究现状

综述了粉末冶金高氮不锈钢的优点和所采取的主要工艺及国内外研究现状。系统总结了高氮不锈钢粉末的制备工艺和固化成形工艺。重点介绍了注射成形-烧结渗氮工艺,分析了部分产品的性能及应用前景,指出注射成形-烧结渗氮工艺是十分有潜力的制备高氮不锈钢的途径