HB360级耐磨板的过冷奥氏体连续冷却转变曲线研究

采用Gleeble3800热力模拟试验机研究HB360耐磨板中过冷奥氏体连续冷却过程的相变规律,利用膨胀法结合金相法建立连续冷却转变(CCT)曲线.结果表明,冷却速率不大于1.5 ℃/s时,HB360耐磨板冷却过程中的转变产物全部为贝氏体组织;冷却速率不小于3 ℃/s时,其转变产物全部为马氏体组织.     

低碳微合金管线钢过冷奥氏体连续冷却转变

利用膨胀法和差热分析法结合金相-硬度法,在Gleeble-1500热模拟机上测定一种低碳微合金管线钢以不同速度连续冷却时的膨胀曲线,结合DSC曲线和金相组织分析,确定该钢的临界温度及相变温度,获得该钢的连续冷却转变曲线(CCT图),研究该钢连续冷却时的奥氏体转变。研究结果表明:添加0.21%Mo起到抑制铁素体和珠光体作用,促进针状铁素体组织的形成,实验钢在5.0～20.0℃/s的较宽冷却速度范围内连续冷却都能得到需要的针状铁素体组织,表明低碳Mn-Nb-Mo微合金管线钢容易得到管线钢工程所需要的组织。     

H08Mn2SiA钢等温转变曲线和连续冷却转变曲线

采用Gleeble-1500热模拟机测定了H08Mn2SiA钢的临界点θAc1,θAc3以及θMs;通过测定不同温度下等温转变和不同冷却速度下连续冷却转变的膨胀曲线,结合金相组织观察和硬度测定,获得了该钢的等温转变曲线和连续冷却转变曲线;研究了其等温转变和连续冷却转变产物的组织形态,比较了所得曲线和同类转变曲线的差别,两者产生差别的原因主要是由于其化学成分、试样原始状态以及奥氏体化条件不同.此外,确定了避免产生贝氏体组织的临界冷却速度为0.50 ℃/s,为该钢的工艺制订和进一步加工提供了依据.     

含Ti系微合金热轧搪瓷钢连续冷却转变曲线及其组织研究

采用热膨胀法和金相法,在Formastor-F试验机上测定了含Ti系微合金热轧搪瓷钢RT360的Ac1和Ac3以及Ms,并测定了该钢在不同冷却速度下连续冷却时的膨胀曲线,获得了该钢的连续冷却转变曲线(CCT曲线)及其相应组织,测定结果为大生产热处理工艺的制定提供了理论基础.当轧后冷却速率＜0.5 ℃/s,可获得理想的多边形铁素体＋少量珠光体组织.淬硬性倾向较小,基本不会出现冷裂纹.     

Nb-B系高强度集装箱钢板材料相变规律研究

在Gleeble-1500热模拟试验机上,测定Nb-B系高强度集装箱钢板材料的动态连续冷却转变曲线(动态CCT曲线),研究冷却速度对材料组织及硬度的影响.结果表明,在试验的冷却速度范围内,相变产物均含有贝氏体组织.当冷却速度小于1 ℃/s时,相变产物含有一定量的多边形铁素体和准多边形铁素体及少量粒状贝氏体;冷却速度等于1 ℃/s时,相变产物含有一定量的准多边形铁素体,但大部分为粒状贝氏体;冷却速度为3、5、10 ℃/s时,相变产物全部由粒状贝氏体组成;冷却速度为15 ℃/s时,相变产物中明显出现板条贝氏体;冷速为20、30 ℃/s时,相变产物板条特征越来越明显.     

28CrMnMoV钢过冷奥氏体连续冷却转变

利用Gleeble-3500热模拟机测量28CrMnMoV钢以不同速度连续冷却时的膨胀曲线,结合差热分析法和金相-硬度法,确定临界点及相变温度点,绘制并分析和应用过冷奥氏体的连续冷却曲线(CCT图),研究实验钢连续冷却时的奥氏体转变.研究结果表明:实验钢过冷奥氏体在高温区可能发生铁素体转变和珠光体转变,中温区可能发生贝氏体转变,低温区可能发生马氏体转变;当冷却速度为0.05～0.5℃/s时,转变产物为多边形铁素体、珠光体和少量贝氏体的混合组织;在1～5℃/s的冷却速度范围内,转变产物为贝氏体;当冷却速度大于5℃/s时,转变产物为马氏体;合金元素Cr,Mo,V有抑制奥氏体扩散分解的作用,以低于1℃/s的速度冷却才会有先共析铁素体和珠光体;锰质量分数较高对贝氏体转变有明显的促进作用,在0.05～10℃/s的较宽速度范围内连续冷却会发生贝氏体转变.根据测得的CCT图指导28CrMnMoV钢的分级控冷工艺,可在减小钢管淬火应力的同时,为V150油套管的高强韧性提供组织保障.     

E36船板钢连续冷却转变行为研究

在THERMECMASTOR-Z热模拟实验机上测定了E36船板钢的连续冷却转变曲线,利用光学显微镜对钢组织进行了观察,并利用维氏硬度计对E36钢硬度进行了测定.结果表明,试验钢奥氏体向铁素体转变温度在785～590℃范围内.当冷却速率小于20℃/s时,随着冷却速率的增快,E36钢晶粒度增加较为明显;而当冷却速率大于20℃/s时,E36钢晶粒度变化趋于平缓.当冷却速率小于20℃/s和大于60℃/s时,E36钢维氏硬度值增加较大;而当冷却速率在20～60℃/s范围时,E36钢维氏硬度的变化趋于平缓.     

一种微合金化马氏体不锈钢的连续冷却转变研究

用膨胀法结合金相与硬度分析研究了一种新型水轮机叶片用V、N微合金化CrNiMo不锈钢的连续冷却转变行为,获得了该钢的连续冷却转变(CCT)曲线及不同冷却条件下的显微组织和硬度。结果表明,试验用钢的1、3、和温度分别为580℃、730℃、295℃和190℃,其贝氏体和铁素体分别在冷速小于0.5和0.2℃/s时出现,冷速在0.056~0.5℃/s之间时,硬度随着冷速的增大迅速增加,尔后随着冷速的增大,硬度缓慢升高。     

3Cr2Mo钢CCT曲线的测定与分析

在Gleeble-1500热模拟机上测定3Cr2Mo钢以不同冷却速度连续冷却时的膨胀曲线,结合金相-硬度法、示差热分析法(DSC)获得该钢的连续冷却转变曲线(CCT曲线).根据测得的CCT曲线,分析以不同冷却速度连续冷却时的组织转变;阐明冷却速度与组织的演变以及硬度变化的关系.比较分析所测CCT曲线与同类转变曲线的异同.研究结果表明:马氏体转变的临界冷却速度为1.0～1.5℃/S;为生产实践和新工艺的制定提供了参考依据.     

含B钒微合金钢的连续冷却相变行为

为开发一种新的低成本高性能含B钒微合金钢和建立其TMCP生产工艺,用MMS-200热力模拟试验机研究了实验钢在连续冷却条件下的相变规律,绘制出实验钢的静态CCT曲线和动态CCT曲线.结果表明:微量的B提高了钒微合金钢过冷奥氏体稳定性,促进了针状铁素体形成,在比较宽的冷却速度范围内能得到贝氏体组织;未变形钢相比于变形钢,在更低的冷却速度甚至0.5℃/s的冷却速度下能得到大部分的贝氏体组织,但两者在5℃/s以上的冷却速度下都得到全部贝氏体组织;变形降低了奥氏体稳定性,促进铁素体转变,含硼钢铁素体转变存在的冷速升高到2℃/s,不含硼钢的其冷速升高到15℃/s;钒微合金钢中B有利于获得高强度的贝氏体组织,冷速5℃/s以上时相变后含硼钢的硬度都高于变形及未变形不含硼钢的硬度.     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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