深冷处理对低碳高合金马氏体轴承钢力学性能及组织的影响

利用洛氏硬度计、X射线衍射仪、扫描电子显微镜及透射电子显微镜等研究了低碳高合金马氏体轴承钢深冷处理后的硬度变化及组织演化。结果表明:深冷处理促使部分残留奥氏体转变为马氏体,导致深冷处理后实验钢的硬度较淬火态硬度有所升高。经深冷处理后实验钢在0~100 h回火过程中的硬度均比未深冷处理实验钢的硬度高。深冷处理促使钢中碳原子偏聚并在回火过程中以碳化物的形式析出,与未经深冷处理的实验钢相比,经深冷处理的实验钢回火后马氏体基体中的含碳量更低,表明实验钢经深冷处理后在回火过程中析出更多的碳化物。透射电镜分析表明,实验钢在回火过程中析出的大量弥散分布的纳米级M2C和M6C型碳化物是实验钢长时间回火后保持高硬度的主要原因。     

正火12CrlMoV钢的回火脆化及影响因素

采用示波冲击韧性试验研究了正火１２ＣｒｌＭｏＶ钢回火脆化的行为、机制及影响因素。结果表明，基体α相的时效析出行为是导致回火脆化的主要原因，峰时效阶段沉淀出细小碳化物质点对位错的强钉扎作用使基体塑性变形能力下降，质点与基体的共格、半共格关系使基体弹性畸变能较高，冲击断裂过程为理解纹萌生控制的脆性失稳断裂。     

三维原子探针表征淬回火Cr-Mo-V-Ni中合金钢的元素分布

将Cr-Mo-V-Ni中合金钢在1 030℃奥氏体化保温0.5h后油淬,在600℃回火2次,每次2h。结合光学显微镜(OM)和扫描电子显微镜(SEM),采用三维原子探针(3DAP)技术分析了淬火态和回火态各元素原子的三维空间分布以及碳化物内部和碳化物/基体界面处元素分布和成分变化。结果表明,淬火试样中C原子由于自回火和短程扩散出现了较为明显的片状偏聚,而其他合金原子Cr、Mn、Mo、Si、V和Ni基本分布均匀;回火试样中C、Cr、Mo和V发生共偏聚形成厚度约10nm的合金碳化物M23C6,Si原子形成一层薄薄的偏聚层包裹着M23C6,而Ni又包裹着Si原子而偏聚于最外层。     

30CrMnSiA钢的回火组织转变

对三种含砷量的３０ＣｒＭｎＳｉＡ钢进行了不同温度的回火处理，在室温下测取了回火处理试样的穆斯堡尔谱，同时对典型试样作了金相和俄歇电子能谱（ＡＥＳ）分析。试验结果表明。３０ＣｒＭｎＳｉＡ钢经淬火十回火处理后，其室温组织为α＇固溶体、碳化物和少量残余奥氏体的混合组织。回火温度不同，碳化物的形态也不一样，残余奥氏体含量随回火温度升高而降低。低温回火脆性主要是残余奥氏体分解与ε＋θ碳化物析出综合作用的结果。     

含铝超高碳钢等温球化工艺的研究

在对超高碳钢进行铝合金化的基础上,利用成分不均匀奥氏体化加热控制,提出了锻态超高碳钢(UHCs-1.6Al)有效的无形变球化工艺,并利用扫描电镜对先共析碳化物的析出及球化进行了观察,分析了碳化物的球化机理.结果表明,通过对UHCs-1.6Al成分不均匀奥氏体化加热,使先共析碳化物在随后冷却时以粒状形式在基体上弥散析出,利用等温过程使其球化长大,并使奥氏体继续冷却时发生离异共析转变,从而获得球化组织;碳化物颗粒的尺寸可以通过等温温度和等温时间控制;当奥氏体化进行充分时,先共析碳化物析出的孕育期延长,部分碳化物在随后共析转变中以片状形式形成;UHCs-1.6Al最佳球化工艺的奥氏体化透烧温度和等温温度分别为850～870℃和780～800℃.     

回火温度对1Cr15Ni4Mo3N钢组织和性能的影响

研究了回火温度对1Cr15Ni4Mo3N钢组织和性能的影响.结果表明,组织中具有高密度位错的板条马氏体及与基体共格的细小沉淀相M2C是该钢具有高强度的主要原因.470℃左右回火强度达到峰值,冲击韧性处于低谷.     

热处理对超高强度钢的精细结构和性能的影响

用透射电镜对钢的精细结构、碳化物的类型、形态、分布及残余奥氏体在基体中的分布进行了观察和鉴别。对钢的机械性能和马氏体亚结构间的关系也进行了研究。结果表明,板条马氏体内存在少量的微孪晶。碳化物往往沿此孪晶界优先析出,残余奥氏体在回火过程中的分解伴有碳原子的扩散。残余奥氏体分解产物之一是串状的渗碳体。板条间渗碳体和回火马氏体间的晶体学关系不符合关系。残余奥氏体的分解性质为上贝茵体反应。冲击韧性开始下降的温度和残余奥氏体开始分解的回火温度一致。残余奥氏体对裂纹扩展起延缓作用。     

一种多元低合金高碳钢的热处理组织及硬度的研究

对一种低合金高碳钢(0.81C,0.65Cr,0.89W,0.54Mo,0.23V)热处理组织及硬度研究表明,该钢退火具有多类型碳化物(M3C,M7C3,M23C6,M6C和MC),在800～840℃区间退火,处于γ相低温区原碳化物部分溶解和新碳化物重新形核生长过程,使碳化物颗粒超细化,平均尺寸0.33～0.34 μm.淬火时,因M3C、M23C6溶解于奥氏体的速度较快,在840～860℃淬火时,硬度可达HRC63～65;未溶碳化物M6C和MC(VC)有利于马氏体细化,但因其数量较少,淬火最高温度不易超过880℃.该钢在低温和中温回火有较好的抗回火性能,并能有效地促进残余奥氏体转变.该钢热处理过程组织结构特征能较好地以相平衡热力学计算结果进行解释.     

塑料模具标准件顶杆用65MnV钢的组织分析

对新型塑料模具标准件顶杆用钢６５ＭｎＶ在淬火和氏温回火过程组织的变化进行了系统的研究。结果表明,６５ＭｎＶ钢的低温淬火组织为位错马氏体组织,随淬火温度的升高,淬火组织逐渐由针状与板条状马氏体的混合组织变成针状马氏体组织,马氏体组织的亚结构由位错型马氏体向孪晶马多体转变。钢在低温回火时析出与基体共格的弥散分布的须状ε碳化物,ε碳化物随回火温度的升高而发生转变,形成非共格的棒状渗碳体组织。     

P92钢表层纳米组织的热稳定性

本文通过表面纳米化处理(SMAT)在P92钢表层中形成纳米组织结构,研究了回火温度对表层纳米组织演化行为和析出行为的影响.结果表明:淬火态和回火态P92钢组织经过SMAT处理后沿深度方向依次是纳米层、剧烈变形层、最终过渡到正常组织.随后分别研究了淬火和回火态SMAT试样经不同温度回火后微观组织的再结晶及长大行为.经SMAT处理的铁素体纳米晶粒在550℃时仍能保持较好的纳米结构,甚至高达650℃时表层晶粒仍为纳米晶,当温度超过760℃时表层组织发生显著的再结晶和晶粒长大现象.纳米晶界能抑制淬火态P92钢在较低温度回火时M23C6碳化物的析出.纳米组织提高了高温回火过程中合金元素在铁素体中的扩散速率,加速了M23C6碳化物的长大过程.不同温度回火过程中SMAT纳米层中析出行为的变化将在本文中详细描述.     

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 Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

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.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

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.     

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.