40CrNiMoA钢的常温蠕变规律及其影响因素

本文研究了热处理强化后的40CrNiMoA钢在低于屈服强度的应力作用下常温蠕变行为和影响因素，揭示了热处理工艺及显微组织对钢材为抗力的影响，结果表明：热处理强化钢中有微量游离铁素体存在，将明显降低蠕变抗力。钢材经高温奥氏体化淬火和Ms点以下的等温淬火并经320℃回火，将使蠕变抗力显著提高。     

1×13代用钢的研究(热处理工艺部分)

一、绪言二、钢的化学成分三、临界点和端淬曲线四、晶粒度五、各种淬火温度和回火温度对机械性能的影响六、淬火温度和回火温度对蠕变抗力的影响七、回火脆性八、冷脆试验九、各种淬火温度和回火温度对组织的影响十、结语十一、附表     

4Cr5MoV1Si钢的热疲劳性能研究

本文研究了热处理工艺，各种表面处理，深冷处理及喷丸等工艺对４Ｃｒ５ＭｏＶ１Ｓｉ钢热疲劳性能的影响，研究结果表明，提高淬火加热温度，细化处理，双重处理，深冷处理，喷丸等都可提高其热疲劳抗力，低氮势等离子氮化，蒸汽处理，电火花表面强化等也对热疲劳抗力有明显改善，本文对热疲劳抗力提高的原因进行了分析。     

不同热处理对热模钢H13的组织和性能的影响

本文研究了热模具钢H13(4Cr_5MoSiV_1)经不同热处理工艺处理后的显微组织和性能。结果表明:H13钢经软氮化处理后,耐磨性、热疲劳抗力较好而冲击韧性较低,250℃等温淬火加回火处理后的冲击韧性最高,热疲劳抗力比正常淬火加回火处理的好,耐磨性较差,300℃等温淬火加回火处理的冲击韧性和热疲劳抗力较低。据此,在受冲击载荷情况下,采用250℃等温淬火加固火热处理工艺较好;受冲击载荷较小时,采用正常淬火加固火软氮化复合热处理工艺较好。     

形变热处理

一、什么叫形变热处理我们知道通常淬火就是将钢材加热到淬火温度(即奥氏体形成温度),保温适当时间,淬入冷却介质中,等过冷奥氏体转变成马氏体后,就完成了淬火过程。而形变热处理则是将加热到淬火温度的钢比较迅速地过冷到 Ar_1以下(一般450～550℃),利用过冷奥氏体仍具有一定塑性的特点,将其进行锻打,使钢变形。但锻打时间不能太长,否则温度过低,钢材会锻裂。锻打后(此时温度约为350℃)再将其淬入冷却介质中,然后再回火,这便是形变热     

钢的磨蚀抗力与力学性能的相关性

对经多种热处理工艺处理的四种钢材,在水轮机模拟圆盘仪上进行了磨蚀试验及力学性能测试。结果表明,钢的磨蚀抗力主要取决于钢材料本身的硬度和冲击断裂过程中单位变形量所吸收的功。     

条链状硫化锰夹杂物对钢轨钢疲劳磨损抗力的弱化

钢轨钢中常含有数量较多的条链状硫化锰夹杂物.试验表明,随热处理工艺不同,夹杂物对钢轨钢的疲劳磨损性能有不同的影响.硫化物的热膨胀系数远大于钢基体,如果钢轨进行淬火、回火处理,因淬火激冷中硫化物的收缩量比基体大,造成夹杂物与基体间的界面开裂.使钢显著弱化,疲劳磨损抗力大大降低;若钢奥氏体化加热后进行缓慢冷却,不但不发生界面开裂,而且还能得到较理想的细珠光体组织,使钢的疲劳磨损抗力不因较多硫化锰夹杂物的存在而明显降低.     

40Cr钢齿轮坯料淬裂原因浅析

40Cr钢齿轮坯料工件经过传统热处理工艺淬火后,其表面常常出现裂纹现象,影响到公司的正常生产。为了进一步提高材料性能,降低材料成本,扩大公司产品的使用范围,本文对坯料表面出现裂纹进行了分析,并对钢材的生产工艺进行了改进和优化,成功地防止了淬火裂纹的产生,取得了较好的应用效果。     

提高三牙轮钻头牙爪使用寿命的研究

本文对20CrMo钢制的三牙轮钻头牙爪的服役条件和主要失效形式进行了分析,指出:牙爪跑道过早发生块状剥落是由于渗碳层的多次冲击接触疲劳抗力不足引起的。采用高温淬火、回火来调整碳化物形态和低温短时加热淬火,适当提高回火温度和滚压强化等措施后。钻头台架试验寿命比原工艺钻头提高了3.5倍,并超过了美国同类型钻头台架试验寿命。油田试验结果,使用寿命与美国同类型钻头相当。文中还对美国钻头用钢、热处理后组织特点、机械性能、钻头台架等作了对比分析和试验,为合理选择象钻头牙爪这样一类承受多冲接触疲劳的零件的用钢及制订热处理工艺提供了依据。     

形变热处理对国产1Cr18Ni9Ti钢热强性的影响

本文研究了形变热处理对国产1Cr 18Ni 9Ti钢蠕变性能的影响,结果表明,多边化工艺可改善国产1Cr 18Ni 9Ti钢的蠕变性能。多边化处理后增大了亚结构的稳定性,适当地保留了形变强化的效果,使蠕变变形量和残余变形量显著地减小,特别是明显地缩短了蠕变第一阶段的时间,减小了第一阶段的变形量。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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