含锆微合金钢焊接区针状铁素体形成观察

借助Gleeble-2000热模拟试验机和TEM对Zr,Zr＋Ti处理试验钢焊接粗晶区中针状铁素体的形核进行了观察。结果表明，Zr和Ti的氧化物都能够作为焊接粗晶热影响区中针状铁素体形核的核心，在提高针状铁素体数量方面，Ti的氧化物比Zr的氧化物更为有效。     

低合金高强钢焊缝针状铁素体形核问题的探讨

研究结果表明 ,通过向焊缝金属过渡微量的Ti B和稀土元素 ,可以使焊缝获得细小、均匀的针状铁素体组织 .通过透射电镜观察发现 :焊缝中合金元素如果能形成细小、难溶的非金属夹杂物 ,就可以成为针状铁素体的形核核心 ;Ti能形成细小、难溶而弥散分布的化合物 (TiO )质点 ,因而对针状铁素体的形核更为有利 ;针状铁素体由许多亚结构组成 .     

热加工对管线钢针状铁素体组织形成的影响

以X70管线钢为实验材料,研究不同变形量和冷却速率对管线钢显微组织的影响.结果表明,在奥氏体未再结晶区进行适量的变形,从而形成位错、形变带和胞状组织等缺陷,可以增加铁素体在奥氏体晶内的形核位置和形核率,增大相变驱动力,有利于在随后的冷却过程中得到晶粒细小的针状铁素体组织;其中变形量ε2=0.4、冷却速率为30～60 ℃/s(油冷)下冷却的试样,能够得到最佳的针状铁素体组织,可以满足工程上要求组织中针状铁素体占80%以上的要求.     

稀土处理钢中夹杂物对晶内针状铁素体形成的影响

分析了稀土处理钢中夹杂物的特征（夹杂物种类、尺寸分布和体积分数）对微观组织中针状铁素体形成的影响.结果表明,钢中夹杂物种类和体积分数对针状铁素体组织的形成非常重要.稀土氧化物（包含稀土氧硫化物）与铁素体具有低至1.9%的错配度降低针状铁素体在夹杂物表面的形核能垒,从而促使它在稀土氧化物上形核.反之,稀土硫化物与铁素体具有高达42.5%的错配度不能诱导生成针状铁素体组织.此外,微观组织中针状铁素体的体积分数随着夹杂物体积分数的增加而增大,当钢中夹杂物体积分数是9.5×10-4时其体积分数达到53%.     

微合金钢焊缝金属中的针状铁素体

系统地分析了微合金钢焊缝金属中针状铁素体组织的形成条件及特点 ,对夹杂物粒径、数量进行了统计分析 ,并阐述了针状铁素体的形核位置。结果表明 ,焊缝金属化学成分和冷却速度是影响针状铁素体 (AF)的主要因素 ,应力对焊缝金属相变的影响很小。焊缝金属中约有 6 0 %夹杂物的粒径都小于 0 .6 μm ,只有不足 10 %的夹杂物粒径大于 1 0 μm ,约有 94 %以上提供针状铁素体 (AF)形核的夹杂物的粒径为 0 .2～ 0 .6 μm。微合金钢焊缝金属最理想的组织是获得大于 6 5 %的针状铁素体 ,其平均板条尺寸约为 1μm。AF在原奥氏体晶内合适粒径的夹杂物上形核长大 ,在较粗大的原奥氏体晶粒和夹杂物粒径大于 2 μm条件下 ,焊缝金属可得到大量的AF。AF在夹杂物上形核机理有 3种 :形核剂与核心共格界面形核机理、高能惰性基体形核机理及高应变能区形核机理。     

氧化物冶金技术及应用

介绍了氧化物冶金技术中非金属夹杂物的性质与作用及境内铁素体的形核机理,并对氧化物冶金技术的若干关键技术问题进行了探讨,分析了氧化物冶金技术的应用现状.     

夹杂物对Ti;Zr微合金钢中针状铁素体形成的影响

采用实验室真空感应炉,炼制了3炉35 kg钢锭.利用MMS-300型热模拟机对实验钢进行线能量为100 kJ/cm,峰值温度为1 400℃的大热输入焊接模拟实验.借助金相显微镜(OM)、扫描电子显微镜(SEM)、能谱分析仪(EDS)和电子探针显微镜(EPMA)对粗晶热影响区(CGHAZ)组织进行观察;研究了热循环后夹杂物的数量、大小、分布和组成对焊接热影响区(HAZ)中针状铁素体形成的影响.结果表明:在粗晶热影响区中针状铁素体的数量随小尺寸氧化物夹杂的数量和面积分数的增加而增加;针状铁素体在Ti,Zr为主的复合夹杂物上形核,这些夹杂物多以Ti,Zr氧化物为核心,表面析出MnS,尺寸在0.5~3...     

微合金钢焊缝金属中的针状铁素体

系统地分析了微合金钢焊缝金属中针状铁素体组织的形成条件及特点，对夹杂物粒径、数量进行了统计分析，并阐述了针状铁素体的形核位置。结果表明，焊缝金属化学成分和冷却速度是影响针状铁素体(AF)的主要因素，应力对焊缝金属相变的影响很小。焊缝金属中约有60％夹杂物的粒径都小于0．6μm，只有不足10％的夹杂物粒径大于1．0μm，约有94％以上提供针状铁素体(AF)形核的夹杂物的粒径为0．2～0．6μm．微合金钢焊缝金属最理想的组织是获得大于65％的针状铁素体，其平均板条尺寸约为1μm，AF在原奥氏体晶内合适粒径的夹杂物上形核长大，在较粗大的原奥氏体晶粒和夹杂物粒径大于2μm条件下，焊缝金属可得到大量的AF。AF在夹杂物上形核机理有3种；形核剂与核心共格界面形核机理、高能惰性基体形核机理及高应变能区形核机理。     

氧化物冶金技术及应用

介绍了氧化物冶金技术中非金属夹杂物的性质与作用及境内铁素体的形核机理,并对氧化物冶金技术的若干关键技术问题进行了探讨,分析了氧化物冶金技术的应用现状。     

Al-Ti-Mg复合脱氧对钢中夹杂物及组织的影响

通过采用Fe-50%Ti、Ni-16.7%Mg和Fe-70.74%Si等合金对工业纯铁脱氧,研究了Al-Ti-Mg复合脱氧低碳钢中夹杂物的类型和尺寸分布规律以及钢的铸态组织.实验结果表明:Ti处理比未加Ti处理试样夹杂物总量增加400mm-2,而且夹杂物明显细化;Ti-Mg复合脱氧,钢中夹杂物的总量相对于Mg单独处理增加200 mm-2;Ti处理后,奥氏体晶粒内出现大量针状铁素体.对比而言,Al-Ti-Mg复合处理钢中针状铁素体分布最为均匀,无块状铁素体出现.     

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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