真空感应熔炼Nb-16Si-22Ti-2Hf-2Cr-2Al合金经高温热处理后的组织和性能

用真空非自耗电弧熔炼法制备了Nb-16Si-22Ti-2Hf-2Cr-2Al母合金锭, 用Y₂O₃坩埚真空感应熔炼对母合金锭重熔, 浇注在温度梯度约为4 ℃/mm的模壳里, 制备出Φ 60 mm×170 mm铸锭, 研究了1500 ℃/100 h真空热处理后铸锭的组织特征对室温抗拉强度和高温压缩性能的影响。结果表明, 真空感应熔炼Nb-16Si-22Ti-2Hf-2Cr-2Al合金经过1500 ℃/100 h热处理后, 合金锭的组成相为Nb_SS枝晶, Nb₅Si₃层片或不规则颗粒和残留Nb₃Si块。块状Nb₃Si的尺寸越大, 发生完全共析转变需要的时间越长、温度越高。热处理合金锭的室温抗拉强度在208~355 MPa之间, 室温延伸率变化不大, 均小于0.3%。残留的粗大块状Nb₃Si和热处理过程中析出的HfO₂是导致合金锭拉伸性能较低的重要原因。合金锭的高温压缩强度受到组织中硅化物相含量的影响, 压缩强度与硅化物含量成正比。      

钕对颗粒增强钛基复合材料组织和性能的影响

采用真空自耗电极电弧熔炼制成钕氧化物颗粒增强钛基复合材料.分析了不同Nd含量的钕氧化物颗粒增强钛基复合材料的组织.测试了复合材料棒材的拉伸、热稳定性、持久和蠕变等力学性能.结果表明,Nd元素的加入能够明显地细化铸锭的低倍组织和β热处理棒材的显微组织.随着加入的Nd含量增加,钕氧化物颗粒尺寸增大,其体积分数也明显增多.Nd元素的加入对复合材料的力学性能有利,尤其是高温性能.     

钛合金真空自耗电弧熔炼技术发展

目前,生产钛及钛合金铸锭的基本方法仍为真空自耗电弧熔炼方法.讨论了真空白耗电弧熔炼钛合金的常见铸锭缺陷和预防措施.回顾了近代真空自耗电弧熔炼(VAR)技术的发展.较详细地介绍了为获得更高质量的铸锭,当前对VAR熔炼过程控制技术所作的努力及取得的进展.指出了未来真空自耗电弧熔炼控制技术的发展方向.     

一种新型Ni-Cr-Fe基合金的成分设计、冶金及强韧化热处理工艺研究

利用增Ni、Al降Cr、Ti含量及CALPHAD方法对Ni-Cr-Fe合金进行了低成本设计;采用发射光谱仪、红外碳硫分析仪、差热扫描量热法、真空感应熔炼和电渣重熔双联冶金、扫描电镜等方法,对合金成分、冶金工艺、热加工工艺、热处理制度进行了系统研究。研究发现:双联冶金工艺成功实现了对设计成分的有效控制,经锻造和轧制热加工,获得均匀洁净的轧制组织;再经900～980℃保温30min固溶,继以720℃保温8h后炉冷至620℃保温8h空冷时效强化热处理,合金力学性能达到Incoloy 925水平。其中轧态组织经直接时效可以获得最佳的综合力学性能。合金轧制时效组织为单一奥氏体细晶组织;固溶时效态组织以奥氏体γ相为主,沿晶或晶内弥散析出MC型一次碳化物。研究结果对于我国新型高强韧Ni-Cr-Fe合金开发具有参考价值。     

冶金标准问答(五)

问:AMS(美国宇航材料规范,下同)5662F(1989—01—01)版)《1775F(968℃)固溶和沉淀热处理的自耗电极或真空感应熔炼In.718耐蚀耐热合金棒材、锻件和环形件》中第3.4.1.1.3条以及AMS5663G(1989-07-01版)《1775F(968℃)固溶和沉淀热处理的自耗电极或真空感应熔炼In.718耐蚀耐热合金棒材料、锻件和     

高温固溶热处理对HIP态FGH96合金中碳化物影响规律的体视学研究

利用金相显微镜,扫描电镜和透射电镜并结合体视学基本原理,对在不同固溶温度和冷却方式(空冷和炉冷)下热等静压(HIP)态FGH96合金中碳化物的数量、空间分布及尺寸分布等进行了定量表征和对比研究。结果表明:HIP态FGH96合金中碳化物主要为富Nb和Ti的MC,在原始颗粒边界(PPB)上分布的碳化物主要为块状,在PPB区域以外分布的碳化物主要由块状和花状MC组成。在1180℃以下进行固溶热处理时,碳化物含量增加并且加剧了合金中的PPB;当固溶温度达到1180℃以上时,随着固溶温度的升高,合金中碳化物数量减少,PPB逐渐消失。1200℃固溶后炉冷,固溶在基体中的碳主要以非PPB碳化物形式重新析出,会导致合金中PPB碳化物数量的降低,即使合金中的碳化物总量与固溶热处理前几乎相同。另外,空冷合金中PPB碳化物尺寸为单峰分布,而炉冷合金中则表现为双峰,后者与炉冷过程中碳化物能够重新析出密切相关。     

时效温度对Ti-5Mo-5V-6Cr-3Al热轧管材组织性能的影响

通过扫描电镜(SEM)和X射线衍射分析(XRD)等手段对新型Ti5563合金热轧态管材经固溶时效和时效处理后的组织及物相含量进行了分析,比较了不同热处理后合金的力学性能,研究了时效温度对材料组织和力学性能的影响。结果表明:直接时效处理是提高Ti5563合金热轧态管材综合性能较为有效的方法;在520~660℃时效处理时,温度越低,α析出相越多,尺寸越小,分布越弥散,合金强度越大;随着温度增加,α析出相减少且尺寸变大,强化作用减弱,合金的塑性增加。     

热处理对Ti-35V-15Cr-0.15Si-0.05C合金热稳定性能的影响

通过对Ti-35V-15Cr-0.15Si-0.05C合金轧制环件取样进行热处理和热稳定性能实验,研究了850℃和950℃固溶处理和950℃固溶后在600℃和700℃实效后的热稳定性能和微观组织。结果表明:合金仅经过固溶处理α相析出不明显,而经过固溶加时效处理后α相在晶界和晶内大量析出,在热稳定性能测试时,经过540℃100h热暴露后,α相进一步析出。合金α相是影响合金拉伸性能的主要因素,在晶界析出的连续α相导致合金塑性急剧下降;通过850℃固溶热处理能够获得较好的室温拉伸和热稳定性能。     

热等静压温度对14Cr-ODS钢显微组织及力学性能的影响

本实验首先利用激光粒度仪、X射线衍射仪(XRD)、扫描电镜(SEM)、能谱仪(EDS)等研究了氧化物弥散强化(Oxides dispersion strengthened,ODS)钢过饱和固溶体合金粉的球磨工艺再利用电子背散射衍射(EBSD)、透射电镜(TEM)、高角环形暗场像(HAADF)、小角度X射线散射(SAXS)等实验方法研究热等静压(HIP)温度对14Cr-ODS钢微观结构和力学性能的影响。实验结果表明,合金粉经过50 h球磨后符合制备ODS钢的各项要求。900℃和1 200℃下热等静压成型的14Cr-ODS钢的晶粒尺寸分别为0.4μm、1 2μm。两种温度下热等静压成型的14CrODS钢中均含有富Y-Ti-O纳米团簇、Y_2Ti_2O_7及大尺寸的富Cr-Ti-O相。900℃下HIP成型14Cr-ODS钢样品中富Y-Ti-O纳米团簇的分布密度为4.96×10~(24)个/m~3。随着热等静压温度的升高,富Y-Ti-O纳米团簇尺寸长大、分布密度降低。900℃下热等静压成型的样品的维氏硬度略高,抗拉强度更强。     

热等静压温度对雾化合金粉制备的9Cr-ODS钢组织和性能的影响

本实验以雾化合金粉制备的9Cr-ODS钢为研究对象,首先利用激光粒度仪、XRD、SEM、EDS等实验手段研究氧化物弥散强化钢雾化合金粉的球磨工艺,再利用EBSD、HAADF、SAXS等实验方法研究热等静压温度对雾化合金粉制备的9Cr-ODS钢的微观结构和力学性能的影响.实验结果表明雾化合金粉经过8 h球磨可以符合制备ODS钢的各项要求.900℃、1100℃、1200℃热等静压成型的9Cr-ODS钢的晶粒尺寸分别为0.36μm、0.94μm和1.66μm.小角度X射线散射结果表明,在900℃、1100℃和1200℃HIP成型的样品中,富Y、Ti、O析出相的分布密度最高值分别为3.94×1022/m3、1.03×1022/m3和8.66×1021/m3.雾化合金粉制备的9Cr-ODS钢中的富Al、Ti、Cr氧化物相的分布密度随着热等静压温度的升高而降低.在雾化合金粉制备的ODS钢样品中均发现了富Y、Ti、O纳米析出相,且成型温度越高,富Y、Ti、O纳米析出相的分布密度越低.900℃热等静压成型样品的力学性能较为优异,成型温度升高,样品的力学性能逐渐下降.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.