西北铝立式淬火炉安装

立式铝合金挤压材固溶处理—淬火炉组是挤压生产线的重要组成部分 ,一些重要的可热处理强化的铝合金特别是2×××系及 7×××系合金的挤压材都要经过固溶—淬火处理。西北铝加工分公司的 4 5MN反向挤压机自 2 0 0 3年11月进入有负荷试车以来 ,立式淬火炉也进入了紧张的安装施工阶段 ,为超高强、高精度铝合金管、棒材技术改造项目于 2 0 0 4年 3月的全线贯通打下基础。西北铝立式淬火炉安装     

快速冷凝Al-Li合金制备的研究

著者采用自行设计的快速冷凝装置制备了快冷Al-Li合金片状粉末,这种片状粉末是由许多微细粉末喷射沉积而成,粉末冷凝速度为10~5—10~6K/s。将片状粉末真空热压成形,然后进行挤压-镦粗-挤压成材,再进行热处理后可得到力学性能优异的Al-Li合金。文章还对片状粉末特征,挤压-镦粗-挤压工艺特点和快冷Al-Li合金时效强化特性进行了详细的讨论。     

全国首套铝锂合金大型锻件下线

正日前,应用于航空航天等高端领域的大直径铝锂合金棒材及管材,在河北宏润核装备科技股份有限公司挤压完成并成功下线。此前,铝锂合金大型锻件只有美国和俄罗斯具备较为成熟的生产制造能力。这种材料比纯铝材料还要轻3%,但是通过挤压成型后,它的强度提高了6%,比铝铜合金、铝镁合金强度要高,而且产品附加值高。大直径铝锂合金棒材及管材的下线,     

介绍新型铝合金IN-9052和IN-9021

IN-9052与IN-9021合金是两种新型的高强度铝合金,是美国国际镍公司用机械合金化法制得的。它们具有良好的综合性能,既有高的抗拉强度与疲劳强度,又有良好的韧性和抗蚀性,是一类在各种性能方面优于现有高强度铝合金的新合金。一机械合金化法所谓机械合金化法,就是用高速的高能球磨机制造合金粉末。合金粉末在这种球磨过程中,既发生破碎,又发生焊合。经过反复破碎与焊合,形成了均匀的合金成分,同时形成了弥散分布的氧化铝与碳化铝质     

机械合金化——一种生产弥散强化合金的新工艺

概述 机械合金化是用高能球磨法制取弥散强化合金粉末的新工艺。利用该工艺能够生产各种类型的、含有弥散难熔化合物粒子和铬、铝等活性合金元素的复杂弥散强化合金粉末,这种粉末经通普粉末冶金方法或其他加工方法进一步处理,可制成机械合金化合金     

轻合金新材料

AL-905XL是一种铝-镁-锂合金。作为新材料,已被用于由WestlandHelicopter和Agusta公司开发和建造的EH101三引擎直升飞机。据报导,研制这种合金是重量减轻计划的部分工作。它是用机械合金化工艺制成的,合金粉末还要经过真空热压,以便为锻     

论压溃强度试验

根据平面曲粱受力分析,推导出压溃强度试验时圆环内外表面的正应力。内表面拉应力导致试样破坏,其过程与弯曲试验相似,σ₊/K值与圆环的几何尺寸R₂/R₁有关。当R₂/R₁≈0.87时,σ₊/K值为1.0,即测得的压溃值K等于弯曲强度σ_bb,还提出用圆环压溃法测定弯曲强度的修正公式。     

简讯

西北铝分公司立式淬火炉开始安装立式铝合金挤压材固溶处理-淬火炉组是挤压生产线的重要组成部分,一些重要的可热处理强化的铝合金特别是2×××系及7×××系合金的挤压材都要经过固溶-淬火处理。西北铝加工分公司的45MN反向挤压机自2003年11月进入有负荷试     

不同的复合粉末状态对W-Ni—Cu重合金显微组织和物理机械性能的影响

本文研究了机械法、化学法、化学镀法、共还原法混料所制得的W、Ni、Cu复合粉末的状态、物理性能、形貌、微观结构及其对合金制造工艺、显微组织和物理机械性能的影响。实验表明,在这四种混料方法得到的复合粉末中,Cu、Ni的存在状态、分布的均匀性以及金属镍的活性显然是不同的、因而影响了合金的制造工艺、显微组织和物理机械性能。比较这四种复合粉末状态对合金性能和研制工艺的影响时发现,用共还原法复合粉末制得的合金,具有优越的工艺特性和较高的物理机械性能,表明了复合粉末的状态对合金的显微组织、性能和制造工艺是十分敏感的。     

本刊第5卷1—4期总目录

研究与试验粉末多孔体的塑性泊松比与致密化方程部分扩散铁基合金粉末的压缩性及烧结 均匀化粉末冶金高强度烧结钢为疲劳特性Fe一Ti合金的液相烧结机理及性能的研究黄培云双对数粉体压制方程的应用热喷涂镍铝放热反应钡钨阴极钨粉某些物理特性的研究稀土氧化物对钻的马氏体相变及机械性能 的影响 工艺与设备高压水雾化生产低含氧量金属粉末装置 及其工艺特征硬质合金姻旋立铣刀刀片的热挤压成形粉末热锻模具设计以机械合金化新工艺制造弥散强化铝一镁 合金采用湿磨工艺提高铁基摩擦材料的性能表面滚压强化对粉末冶金烧结钢疲劳强 度的影响 …     

氧化锆含量对钼合金组织和性能的影响

采用粉末冶金工艺制备了含不同质量分数氧化锆（ZrO₂）的钼合金棒材,通过拉伸力学性能测试、硬度测试、光学显微镜观察等分析手段,研究了ZrO₂含量对钼合金显微组织和力学性能的影响。结果表明:ZrO₂的添加细化了钼合金晶粒,随着ZrO₂质量分数的增加,钼锆合金的硬度和室温抗拉强度增加。当ZrO₂质量分数为2.5%时,钼锆合金的硬度达到最大值（HV₁₀ 240）,抗拉强度达到最大值（820 MPa）。     

人工髋关节用复合多孔钛股骨头制备方法的研究

本研究采用等离子旋转电极制取的Tc4钛合金球形粉末,涂覆在致密芯杆上,制成柄部表面多孔层厚度约2mm的复合多孔钛股头。本文着重研究了原始粉末粒度、烧结制度、基体表面粗糙度对复合多孔层的孔径、孔隙度以及多孔层与基体间结合强度的影响,同时还测定了复合多孔钛股头的机械性能。研究结果表明,材料的最大孔径主要取决于原始粉末粒度,并随粉末粒度的增大而线性增加。影响结合强度的主要因素是烧结制度、原始粉末粒度和基体表面粗糙度。其结合强度随烧结温度的提高、保温时间的延长、原始粉末粒度的下降和基体表面粗糙度的增加而增加。孔隙度仅取决于粉末的堆积状态。所获得的复合多孔钛股头的机械性能为σ_b=830~880 MPa,σ_0.2=810~840 MPa,σ=9.5~12.0%,ψ=26.0~33.0%。     

Mechanical properties and fracture behavior of an ultrafine-grained Al-20 wt pct Si alloy

The effect of powder particle size on the microstructure, mechanical properties, and fracture behavior of Al-20 wt pct Si alloy powders was studied in both the gas-atomized and extruded conditions. The microstructure of the as-atomized powders consisted of fine Si particles and that of the extruded bars showed a homogeneous distribution of fine eutectic Si and primary Si particles embedded in the Al matrix. The grain size of fcc-Al varied from 150 to 600 nm and the size of the eutectic Si and primary Si was about 100 to 200 nm in the extruded bars. The room-temperature tensile strength of the alloy with a powder size <26 μm was 322 MPa, while for the coarser powder (45 to 106 μm), it was 230 MPa. The tensile strength of the extruded bar from the fine powder (<26 μm) was also higher than that of the Al-20 wt pct Si-3 wt pet Fe (powder size: 60 to 120 μm) alloys. With decreasing powder size from 45 to 106 μm to <26 μm, the specific wear of all the alloys decreased significantly at all sliding speeds due to the higher strength achieved by ultrafine-grained constituent phases. The thickness of the deformed layer of the alloy from the coarse powder (10 μm at 3.5 m/s) was larger on the worm surface in comparison to the bars from the fine powders (5 μm at 3.5 m/s), attributed to the lower strength of the bars with coarse powders.     

Mechanical properties and fracture behavior of an ultrafine-grained Al-20 wt pct Si alloy

The effect of powder particle size on the microstructure, mechanical properties, and fracture behavior of Al-20 wt pct Si alloy powders was studied in both the gas-atomized and extruded conditions. The microstructure of the as-atomized powders consisted of fine Si particles and that of the extruded bars showed a homogeneous distribution of fine eutectic Si and primary Si particles embedded in the Al matrix. The grain size of fcc-Al varied from 150 to 600 nm and the size of the eutectic Si and primary Si was about 100 to 200 nm in the extruded bars. The room-temperature tensile strength of the alloy with a powder size <26 μm was 322 MPa, while for the coarser powder (45 to 106 μm), it was 230 MPa. The tensile strength of the extruded bar from the fine powder (<26 μm) was also higher than that of the Al-20 wt pct Si-3 wt pct Fe (powder size: 60 to 120 μm) alloys. With decreasing powder size from 45 to 106 μm to <26 μm, the specific wear of all the alloys decreased significantly at all sliding speeds due to the higher strength achieved by ultrafine-grained constituent phases. The thickness of the deformed layer of the alloy from the coarse powder (10 μm at 3.5 m/s) was larger on the worn surface in comparison to the bars from the fine powders (5 μm at 3.5 m/s), attributed to the lower strength of the bars with coarse powders.     

Alloying aluminum with magnesium for ductility at warm temperatures (25 to 250°C)

Solute additions generally increase flow stress and decrease ductility. However, in an earlier study which compared the tensile behavior of a commercial Al-4 pct Mg alloy (5182-0) relative to pure aluminum, the commercial alloy exhibited increases in both strength and ductility at elevated temperatures (<250°C). To more fully understand this unexpected behavior, a series of high purity Al-Mg alloys (0 to 6 wt pct) were tested over the same range of temperatures (25 to 250°C) and initial strain rates (10^-4 to 10^-1 s^-1) as in the earlier study. At ambient temperature the Mg solutes decreased elongation while increasing flow stress, but as the temperature was increased to 250°C the elongation increased with Mg content. This increase in ductility accompanied the linear increases in strain-rate sensitivity which occurred with increasing amounts of Mg. Stress relaxation tests indicated that Mg solutes increase the amount of dynamic recovery occurring at elevated temperatures. These results are explained on the basis of an increased amount of vacancies in the Al-Mg alloys relative to pure aluminum.     

Al-Fe-Ce alloys based on water-atomized powders for high-temperature applications

The microstructure and mechanical properties of Al-Fe-Ce alloys based on water-atomized powders between 20 and 300 °C are examined in comparison with the properties of similar alloys produced by other rapid crystallization techniques. Changes in atomization parameters vary both the cooling rate (from 10⁴ to 10⁶ K/sec) and powder size distribution (from 5 to 100 µm). The excellent compactability of water-atomized powders facilitates powder consolidation, which is based on hot extrusion and cold pressing of degassed powders. The mechanical properties are examined by tensile tests. The ultimate tensile strength is 500 to 550 MPa at 20 °C and 270 to 300 MPa at 300 °C at adequate plasticity. The properties achieved are comparable with those of similar alloys known from the literature.     

Microstructural evolution and superplasticity of Al-5.8Mg-0.23Mn alloys processed by reciprocating extrusion

This study developed the reciprocating extrusion method to refine the inclusions and grain structure of Al-5.8Mg-0.23Mn alloys to enhance their strength and superplasticity without prior homogenization treatment. Alloy cast billets were extruded with an extrusion ratio of 10:1 at 450 °C for one, five, or ten passes. The grain size was reduced to 4.6 μm, and the coarse inclusions refined to 2 μm, after ten passes. A subgrain structure was formed in the interior of the fine grains, indicating that dynamic recrystallization occurred during extrusion. In this study, dynamic recrystallization in the billet was repeatedly induced by a number of extrusion passes until a limiting grain size was obtained. Thereafter, dynamic recrystallization was no longer activated because grain boundary sliding, instead of dislocation gliding, accommodated the deformation strain required for extrusion. The alloys extruded in ten-passes extrusion were found to be stronger and more ductile than commercial Al-Mg alloys and showed improved superplastic behavior at 500 °C not only from low to high strain rate but also with a small flow stress of less than 30 MPa. These advantages demonstrate that reciprocating extrusion can produce Al-Mg alloys with improved mechanical properties making them good candidates for high-strain-rate superplastic forming.     

MECHANICAL PROPERTIES OF SINTER/FORGED LOW-ALLOY STEELS

Abstract

The paper describes preliminary work on sinter/forged low-alloy steels. The mechanical properties and structures of both atomized and blended alloys were investigated. By using a good-quality atomized powder of the SAE 4600 type, tensile and fatigue properties equivalent to those of wrought steels could be obtained. Atomized alloy powders with higher oxygen contents had poor ductility and impact values because of surface oxides on the powder particles.

Blended iron alloys gave tensile strengths up to 72 tonf/in² (1112 MN/m²) with much higher ductility and impact-resistance than would be obtained with conventionally pressed and sintered alloys.     

Mechanical properties of metal injection moulded 316L stainless steel using both prealloy and master alloy techniques

Abstract

Stainless steel 316L MIM components can be made from either prealloyed powders or from master alloys blended with carbonyl iron powder. In this study these two techniques were compared using prealloyed and master alloyed gas atomised powders of ? 16 μm and ? 22 μm sizes. Four different compounds were prepared, characterised and injection moulded into tensile bars. The bars were compared for green strength, green defects, sintered strength and microstructure. The green components are stronger when carbonyl iron powder is used with the gas atomised master alloy. This material also seems to be less susceptible to moulding defects. The sintering strength of the material produced using the pre-alloyed powder was higher than the master alloyed prepared material. Little difference in mechanical properties existed between the materials fabricated from gas atomised prealloyed ? 16 μm and the ? 22 μm powders. Also, the viscosity of the mixtures was higher for the ? 16 μm material and the master alloy mixtures than for the –22 μm gas atomised prealloyed powders.     

Structure and properties of rapidly solidified 7075 P/M aluminum alloy modified with nickel and zirconium

Aluminum alloy 7075 was modified by additions of 1.1 wt pct nickel and 0.8 wt pct zirconium, rapidly solidified by ultrasonic gas atomization, canned, cold compacted, hot extruded, and evaluated in terms of structure and properties. Significant improvements in tensile strength (627 MPa YS and 680 MPa UTS) and crack growth rates were realized, along with a decrease in fracture toughness (23.7 MPa√m) while maintaining ductility (10 pct elong.) as compared to nominal I/M 7075 behavior. The stress for 10⁷ cycles fatigue life was greater than 275 MPa, which represents a 73 pct increase over that of I/M 7075. A variety of experiments was performed to evaluate effects on strength, ductility, and on structure. The variables were: powder size distribution, extrusion ratio, extrusion profile, different size fractions from the same lot of powder, and different locations of test bars in the several extrusions. Tensile properties, toughness, and fatigue properties were not importantly influenced by the location of test bars in the cross section or length of rectangular extruded bars. A comparison of mechanical properties from extruded bars prepared from ?53 μm powdersvs 53 to 250 μm powders showed a small loss of ductility and fatigue stress for 10⁷ cycles for the fine powder product. Higher extrusion ratios were beneficial for mechanical properties.