42CrMo铸造环坯高温拉伸性能

以常用轴承材料42CrMo钢为研究对象,采用Gleeble-3500热力试验模拟机,通过高温拉伸试验,分析了铸造42CrMo钢的高温拉伸力学性能。建立了抗拉强度模型,并验证了模型的准确性;计算了硬化系数和应变速率敏感系数。结果表明,铸造42CrMo钢的硬化系数随加热温度升高而减小,随应变速率增大而增大。应变速率敏感系数则随温度升高而增大,随应变速率增加而减小。     

Cr-Mo-V系高强度钢的应力腐蚀开裂行为

用改进的WOL型试样研究了Cr-Mo-V系高强度钢在3．5％NaCl水溶液中的应力腐蚀断裂行为，并与常用的42CrMo钢进行了对比。结果表明，回火温度对实验钢的应力腐蚀开裂行为有显著影响。当回火温度较低时，Cr-Mo-V钢的KISCC较低，且随回火温度的升高缓慢提高，断裂方式主要为沿晶断裂；当回火温度超过约873K后，KISCC显著提高，断口中穿晶断裂所占的比例明显增加，断裂方式逐渐转变为穿晶型断裂为主。在相同的强度水平下，Cr-Mo-V钢的KISCC高于42CrMo钢，且在低强度水平下二者差别较大。对42CrMo钢，KISCC随屈服强度升高呈指数下降。但对Cr-Mo—v钢，则并非如此，即在强度保持不变（Rp0.2=1410—1440MPa）的条件下，KISCC随回火温度升高而明显提高。Cr-Mo—V钢和42CrMo钢的KISCC均随回火温度的升高呈指数关系增加。     

CO_2驱采出井井下附件材料的腐蚀评价与优选

采用高温高压动态循环腐蚀试验,研究了35CrMo钢、42CrMo钢、3Cr13不锈钢、45号钢、304L不锈钢、316L不锈钢等6种材料在温度为30~65℃,压力为2 MPa,液相介质流速为1.2m/s的CO_2驱采出井环境中的腐蚀规律。采用扫描电子显微镜(SEM)和附带能谱仪(EDS)对腐蚀产物的形貌和成分进行了表征。结果表明:在本试验环境中,304L和316L不锈钢均未发生腐蚀;3Cr13不锈钢受到轻微CO_2腐蚀,腐蚀速率低于行业标准要求的0.076mm/a,其他材料的腐蚀速率均偏大,其在CO_2驱油田采出井环境中的腐蚀速率由大到小为:45号钢42CrMo钢35CrMo钢。合金中的Cr含量较低时(0~9%),随着Cr含量的升高,含Cr合金的耐CO_2腐蚀性增强;环境温度为30~65℃时,随着温度的升高,合金的腐蚀速率增大,这与腐蚀产物膜的生长情况有关。     

42CrMo钢在氯离子溶液中的腐蚀行为研究

目的通过研究42CrMo钻具用钢在常温下不同Cl~-浓度溶液中的腐蚀行为,为其腐蚀速率的预测奠定一定基础。方法采用浸泡实验、电化学测试技术研究42CrMo在不同浓度NaCl溶液中的平均腐蚀速率和电化学特性,并结合SEM扫描电镜对浸泡58 h后的挂片试样进行分析。结果浸泡实验分析表明,当Cl~-达到60 g/L时,42CrMo钢的腐蚀速率达到最大值,为0.124 g/(m~2·h);当Cl~-浓度继续增大时,腐蚀速率随Cl~-浓度的增加而逐渐减小。开路电位Eocp分析表明,随着Cl~-浓度的增加,Eocp总体呈现下降趋势,显示出较大的腐蚀倾向性。极化曲线分析表明,阴极极化曲线的斜率明显比阳极大,并且自腐蚀电流密度在60 g/L Cl~-溶液中达到最大值,为5.952 35μA/cm~2。腐蚀形貌研究表明,42CrMo浸泡58 h后,表面的腐蚀产物分布并不均匀,均发生了局部点蚀现象。结论随着Cl~-浓度的不断增大,42CrMo钢的平均腐蚀速率呈现先增大后减小的趋势,且在Cl~-为60 g/L时,平均腐蚀速率最大。42CrMo钢在静态常温下高Cl~-浓度溶液中以局部点蚀为主,其电化学腐蚀过程主要受阴极去氧极化的控制。     

Cr-Mo-V系高强度钢的疲劳断裂行为

采用旋转弯曲疲劳和疲劳裂纹扩展实验研究一种新型Cr-Mo-V系高强度钢在不同回火温度下的疲劳破坏行为.结果表明,Cr-Mo-V系高强度钢的旋转弯曲疲劳极限σ-1与抗拉强度Rm的比值σ-1/Rm随回火温度的升高而增加.在相同的强度水平下,实验钢的疲劳极限高于商业42CrMo钢.对疲劳断口裂纹源的分析表明,实验钢的疲劳裂纹主要起源于钢中的非金属夹杂物.采用C-T试样测定疲劳裂纹扩展速率的实验结果表明,Cr-Mo-V系高强度钢疲劳裂纹扩展第二阶段的扩展速率随回火温度升高而有所降低.在1500 MPa强度水平下,实验钢的疲劳裂纹扩展速率低于42CrMo钢.     

动态应变时效对35CrMo钢力学性能的影响

采用慢应变速率拉伸、电子显微镜等现代分析方法,研究了35CrMo钢动态应变时效现象对力学性能的影响.结果表明:在应变量为5％、应变速率为5×10-4s-1的不同温度(293、323、373和473 K)下动态应变时效后的35CrMo钢的伸长率变化不大,但动态应变时效后的抗拉强度均明显增加;35 CrMo钢动态应变时效的最佳温度为373K.35CrMo钢试样在室温下经过动态应变时效处理之后的室温屈服强度明显增加.     

介质温度对35CrMo钢在CO2环境下腐蚀的影响及其机理

为了研究35CrMo钢钻采工具的井下腐蚀行为,模拟了油田地层水环境,通过腐蚀质量损失、交流阻抗等试验方法,测试了该钢材在30、60、80和100 ℃等不同温度下的耐腐蚀性,用SEM、EDS、XRD手段对腐蚀产物膜的形貌、成分、结构进行了分析,对钢材在不同温度下的腐蚀机理进行探讨。结果表明,温度可以改变35CrMo钢的腐蚀产物膜结构,在30～60 ℃温度范围内,随温度升高,腐蚀速率变大,35CrMo钢表面的腐蚀产物膜为片层状、较薄且结构松散,主要成分为FeCO₃和Cr(OH)₃;在60～100 ℃温度范围内,随温度升高,腐蚀产物膜致密性变好,晶粒变细,腐蚀速率变小,腐蚀产物膜上层为晶体,主要成分为FeCO₃,下层为片状生成物,成分为Cr(OH)₃。     

常用集输管线钢在CO_2多相流中的腐蚀行为

用高温高压釜考察了动态条件下温度、CO2分压和油水比等因素对X65、Q235B、16Mn三种钢的CO2腐蚀行为的影响;用扫描电镜对腐蚀试样进行了表面形貌观察,对腐蚀产物进行了能谱分析与X射线衍射分析。结果表明,钢在CO2多相流腐蚀介质中的耐蚀顺序为:16Mn,Q235B,X65。随着含水量、压力的增加,三种钢的腐蚀速率增加;随着温度的升高,钢的腐蚀速率先升高,60℃时最大,90℃时腐蚀速率最小。     

温度对S135钻杆钢在3.5%KCl溶液中腐蚀行为的影响

基于理论分析和采用挂片实验,SEM以及电化学测量技术,研究了S135钻杆钢在不同温度下3.5%KCl溶液中的腐蚀行为.结果表明:钻杆钢试样开路电位随着温度升高负移;不同温度下的腐蚀控制因素是造成腐蚀速率变化的主要原因;电化学腐蚀主要受阳极反应控制;系统"弥散效应"随温度升高而增强,平均腐蚀速率呈现先增加后降低的趋势.     

42CrMo4钢高温拉伸断裂准则与机理的研究

由于变形温度和应变速率是影响42CrMo4钢高温变形损伤断裂行为的重要因素,因此综合考虑了变形温度和应变速率对材料断裂的影响。基于Cockroft-Latham断裂准则,引入温度补偿应变速率因子Zener-Hollomon参数作为修正系数对Cockroft-Latham断裂准则进行改进。通过Gleeble-3800D热模拟试验机对42CrMo4钢进行了温度为950～1100℃、应变速率为0.01～10 s~(-1)条件下的高温拉伸试验。利用试验结果采用线性拟合确定修正系数,得到改进后的断裂准则,将准则预测结果与试验结构对比验证,二则能很好吻合。利用扫描电镜观察试样拉伸断裂断口的组织形貌。结果表明:42CrMo4钢高温拉伸断裂是典型韧窝型韧性断裂,随着温度的提升,材料塑韧性明显提高;随应变速率的提高,材料塑韧性随之不显著降低。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.