国产管线钢的环境开裂性能研究

采用电化学测试和慢应变速率实验(SSRT)研究了国产X70管线钢在近中性pH和高pH溶液中的应力腐蚀破裂(SCC)行为.结果表明,X70钢在高pH溶液和近中性pH溶液中的阳极极化曲线表现出明显的差异:在高pH溶液中有明显的活化-钝化转变而在近中性pH溶液中则无;在近中性pH溶液中,X70管线钢的开裂模式是穿晶型的,具有准解理特征,并且随着外加阴极电位的降低,SCC敏感性增加,氢致破裂占主导;随温度的下降以及溶液中CO2含量的增加,溶液pH值降低,SCC敏感性增加.在高pH溶液中,在阴极极化时,X70钢表现出与在近中性pH溶液中类似的破裂行为和特征,即SCC敏感性随电位降低而增大,裂纹数目少而大,裂纹易扩展;但在阳极极化时,裂纹数目多而小,易萌生但难扩展.在2种溶液中阳极极化时,均存在SCC敏感电位区.     

国产管线钢的环境开裂性能研究

采用电化学测试和慢应变速率实验(SSRT)研究了国产X70管线钢在近中性pH和高pH溶液中的应力腐蚀破裂(SCC)行为.结果表明,X70钢在高pH溶液和近中性pH溶液中的阳极极化曲线表现出明显的差异:在高pH溶液中有明显的活化-钝化转变而在近中性pH溶液中则无;在近中性pH溶液中,X70管线钢的开裂模式是穿晶型的,具有准解理特征,并且随着外加阴极电位的降低,SCC敏感性增加,氢致破裂占主导;随温度的下降以及溶液中CO2含量的增加,溶液pH值降低,SCC敏感性增加.在高pH溶液中,在阴极极化时,X70钢表现出与在近中性pH溶液中类似的破裂行为和特征,即SCC敏感性随电位降低而增大,裂纹数目少而大,裂纹易扩展;但在阳极极化时,裂纹数目多而小,易萌生但难扩展.在2种溶液中阳极极化时,均存在SCC敏感电位区.     

核用SA508-4N钢粗晶区再热裂纹敏感性评价

采用等温恒速拉伸方法评价了核用SA508-4N钢焊接粗晶区(CGHAZ)的再热裂纹敏感性。使用激光共聚焦、扫描电镜和透射电镜观测和分析粗晶区和断口处的组织、裂纹以及断口形貌,结果表明：SA508-4N钢的母材为回火马氏体,较高含量的碳和铬影响碳化物的大小和分布状态,粗晶区马氏体的形成不利于抑制再热裂纹的产生。碳化物的析出使晶内和晶界的强度不同,当晶内强度大于晶界强度时形成沿晶脆性断裂;当晶内和晶界强度的差距较小时断裂形式包括穿晶和沿晶断裂。SA508-4N钢粗晶区对再热裂纹不敏感,成分A粗晶区的抗再热裂纹能力比成分B的高。在实际生产中,优选的工艺参数为：成分A、焊接t_8/5为25 s、焊后热处理温度580℃。     

16Mn钢在空气和3.5% NaCl溶液中的疲劳行为

采用哑铃状平板试样,分别研究了16Mn钢在空气中和3.5%NaCl溶液中的疲劳行为,获得了S-N曲线,并对疲劳试样的表面和断口形貌进行了观察。结果表明:3.5%NaCl溶液(与空气相比)使16Mn钢的疲劳强度有较大程度的降低,在空气中16Mn钢的疲劳极限为200 MPa,而在3.5%NaCl溶液中该钢则不存在疲劳极限;空气中的疲劳试样只有一个萌生于试样表面基体的裂纹源,而3.5%NaCl溶液中该钢的疲劳试样一般有多个裂纹源,除了极少数萌生于试样表面基体处,其余均萌生于表面的点蚀坑;空气中疲劳试样裂纹扩展区的断口形貌以疲劳辉纹为主,而3.5%NaCl溶液中的则以沿晶开裂等脆性特征为主。此外还对空气中16Mn钢的疲劳极限进行了预测,预测值与试验值基本吻合。     

富锌涂层、阴极极化对管线钢应力腐蚀开裂敏感性的影响

为加强对油气管线钢腐蚀失效机理的认识,采用动态慢应变速率拉伸试验(SSRT),研究了弱酸性环境中富锌涂层与阴极保护对16Mn和X80 2种不同强度级别管线钢应力腐蚀开裂(SCC)敏感性的影响,探讨了2种管线钢的SCC机理.结果表明:在5%NaCl 0.5%CH3 COOH 酸性溶液中,16Mn钢的SCC机理以阳极溶解为主,富锌涂层和阴极保护均能有效提高16Mn钢的SCC抗力,前者效果优于后者;X80钢的SCC机理以氢脆为主,富锌涂层和阴极极化均促进其SCC过程,但富锌涂层提高X80钢SCC敏感性的程度低于与涂层自腐蚀电位相近的阴极极化作用.     

Ca处理对Ti大线能量焊接非调质低合金高强钢组织与性能的影响

研究了Ca处理对含Ti大线能量焊接非调质低合金高强钢的组织与性能的影响.Ca处理钢组织结构得到细化,大线能量焊接热模拟热影响区(HAZ)晶界铁素体生长被抑制,其钢板及HAZ的强韧性均得到有效提高.Ca处理使含Ti钢热影响区氧硫化物复合夹杂物由片条状转变成球状,并从TiMnOS占主导变为TiCaMnOS-Al2O3占主导,提高了晶内针状铁素体形核能力.     

地铁车钩牵引梁应力腐蚀开裂的机理

某7020铝合金地铁列车在检修过程中发现车钩牵引梁存在开裂现象,失效分析结果表明该裂纹性质为应力腐蚀开裂(SCC)。采用断裂力学双悬臂梁(DCB)试样,对高强度7020铝合金的应力腐蚀开裂特征进行了研究。结果表明:7020铝合金在含氯离子的水溶液环境中对SCC敏感。板料的Z-X和Z-Y方向有SCC裂纹萌生,裂纹开始萌生的时间较长,扩展速度较慢,SCC裂纹的特征为水平扩展,表面有呈台级式不连续扩展和群集的现象,开裂面为沿晶扩展,和车钩牵引梁的裂纹特征相同。     

X100管线钢在含SRB的盐碱土壤溶液中的SCC行为

为证实SRB对X100管线钢在土壤中应力腐蚀行为的影响,采用慢应变速率拉神(SSRT)实验和SEM研究了X100管线钢在含有SRB的海滨模拟盐碱土壤溶液的应力腐蚀开裂行为.结果表明:X100钢母材和焊缝在无菌的海滨模拟盐碱土壤溶液的断裂模式为穿晶+沿晶SCC混合断裂,而在有菌的海滨模拟盐碱土壤溶液的断裂模式为穿晶SCC断裂;且X100钢母材和焊缝在无菌的海滨模拟盐碱土壤溶液中的SCC敏感性高于有菌时的,说明SRB的存在抑制了X100钢的脆变,导致X100钢的SCC敏感性降低.     

淬火微观组织对重轨钢疲劳裂纹扩展速率的影响

以U75V重轨钢CT(Compaction test)试样为研究对象,分别研究了冷速为3℃/s、5℃/s及空冷轧态的组织对稳定区(疲劳扩展Ⅱ区)疲劳裂纹扩展速率的影响,疲劳试验在高频共振疲劳试验机上进行。研究结果表明:疲劳裂纹扩展速率随着珠光体片层间距的减小而降低,冷速由大到小(5℃/s、3℃/s、空冷)所对应的n值分别为3.603 05、3.631 18和3.885 28;珠光体组织的疲劳裂纹断裂形式主要以穿晶断裂为主,同时伴随部分沿晶断裂;片层间距影响裂纹扩展路径的偏折程度,偏折程度随片层间距的减小而增大,增大的裂纹偏折路径对裂纹扩展的阻碍作用增强,有利于疲劳裂纹扩展速率的降低。     

高Cl~-环境对M152和17-4PH高强钢应力腐蚀开裂行为的影响

利用中性盐雾实验、慢应变速率拉伸实验研究M152和17-4PH高强钢在高Cl~-环境中的应力腐蚀行为和机理。结果表明:M152和17-4PH钢在高Cl~-环境中均有一定的应力腐蚀开裂(SCC)敏感性,且随着前期中性盐雾时间的延长,其伸长率逐渐降低,SCC敏感性逐渐升高;通过扫描电子显微镜对试样的断口和侧边裂纹进行观察比较发现,中性盐雾时间的延长会使M152和17-4PH高强钢的断裂机制由韧性断裂向脆性断裂转变。分析得出M152和17-4PH钢在高Cl~-环境中发生SCC是阳极溶解(AD)和氢脆(HE)的协同作用,Cl~-会加速AD过程。经过不同时间中性盐雾后17-4PH钢的SCC敏感性均比M152钢要高,HE作用也越明显。高Cl~-环境中,17-4PH高强钢相对M152钢更易发生SCC。     

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.