中碳Si-Mn奥氏体一贝氏体耐磨钢的研究

试验研制了以硅、锰为主的中碳Si－Mn奥氏体一贝氏体钢,可在铸态、正火和缓冷以及锻后空冷条件下均可获得贝氏体组织,且具有高硬度和良好的韧性,其冲击磨损性优于高锰钢．     

多元低合金空冷贝氏体铸钢的组织与性能

以A3废钢为主要原料,添加Si, Mn, Cr, Cu等多种微量合金元素,加入少量Mo、稀土进行微合金化和变质处理,在空冷条件下,获得了综合性能优良的贝氏体钢.主要研究了该钢的成分、组织和性能之间的关系.结果表明,低合金空冷贝氏体钢的生产工艺简单,贵重合金元素加入量少,生产成本低,具有优良的强韧性和耐磨性,综合效益显著.     

一种新型低碳贝氏体钢的研制

以Mn,Si,Cr为主要合金元素,设计并制造一种新型的低碳贝氏体钢.系统地研究了选定成分和工艺对贝氏体钢显微组织和力学性能的影响.结果表明,该钢种在设定的等温淬火工艺条件下,可以获得无碳化物析出的奥氏体-贝氏体组织.含有该组织的钢具有良好的综合力学性能.     

中碳低合金空冷贝氏体铸钢的组织与性能研究

以A3钢边角料为原料添加锰铁、硅铁、铬铁和钼铁以及少量的稀土,通过中频感应熔炼及相应的炉前处理,设计了1种铸钢,通过不同的热处理工艺制度,在空冷条件下获得了贝氏体组织.通过16种不同的热处理工艺研究热处理对组织的影响规律,借助光学金相显微镜(OM)、扫描电子显微镜((SEM)、硬度计和冲击试验机等手段分析研究了试验钢热处理态、回火态以及不同热处理工艺规范下的力学性能,利用透射电子显微镜(TEM )分析研究了空冷贝氏体组织组成以及析出的碳化物的成分.结果表明:合金元素C, Si. Mn, Mo, Cr的合理有效配合,可使钢在空冷条件下,在较宽的成分范围内得到以贝氏体为主的显微组织.TEM分析证明基体组织以下贝氏体为主,兼有部分上贝氏体,同时还有少量的残余奥氏体存在,贝氏体中的碳化物有渗碳体和ε-碳化物.贝氏体钢的硬度在40～49HRC范围内变化,冲击韧性在44～70J/cm2范围内变化;     

新型微变形齿轮钢的显微组织及亚结构

为了减少汽车齿轮的淬火变形,研制了一种新型微变形齿轮钢.用透射电子显微镜对这种钢在空冷状态下的显微组织进行了研究.结果表明,新型微变形齿轮钢在空冷条件下即可获得具有精细结构的无碳化物贝氏体铁素体束状组织,贝氏体铁素体片条、亚片条及亚单元被残留奥氏体膜包围,这种组织使微变形齿轮钢具有良好的强度和韧性,尤其冲击韧性显著提高.由于具有良好的强韧性配合,新型微变形齿轮钢在空冷条件下即可满足汽车齿轮复杂的工况要求.     

重型汽车专用非调质钢前轴工业性生产工艺

针对国内卡车前轴使用调质钢制造带来的产品力学性能下降或成本过高等缺点,自行设计一种非调质钢制造卡车前轴,使用Mn、Si等廉价合金元素代替调质钢中Cr、Ni、Mo等较贵重合金元素,所设计的空冷贝氏体钢成分定为Mn-Si-V-B系,钢号为18Mn2SiVB.通过冶炼操作研究,实验确定前轴热处理工艺,进行工业实验.经过相组织分析和疲劳强度实验对产品进行检验.结果表明,冶炼和连铸连轧条件基本满足18Mn2SiVB钢的生产设计要求.采用设计用钢18Mn2SiVB代替45号或40CrMo和40CrNiMo制造卡车前轴,从其力学性能测试结果分析,能够满足使用要求;在制造工艺上采用锻后空冷代替原有锻后调质的方法是可行的.     

低碳粒状贝氏体钢强韧化机理的探讨

对 1 4SiMn3Mo低碳贝氏体钢的强韧性及组织作了研究 .结果表明 :该钢连续空冷后 ,组织为粒状贝氏体 ,韧性差、屈强比低 .经 30 0℃回火可获得良好的强韧性配合 ,而经40 0 - 50 0℃回火产生回火脆性 .根据回火过程中显微组织及残余奥氏体稳定性等方面的变化 ,探讨了粒状贝氏体钢的强韧化机理及回火脆化原因     

退火工艺对钎具用钢22Si2MnCrNi2MoA带状组织的影响

使用光学显微镜、扫描也镜和能谱仪等研究了钎具用钢22Si2MnCrNi2MoA动态连续冷却相变规律和退火工艺优化,分析了冷却速度对连续冷却转变曲线和相变组织的影响,探讨了22Si2MnCrNi2MoA钢带状组织成因及改善措施.22Si2MnCrNi2MoA钢具有较高的淬透性,在形变后空冷即可得到贝氏体+马氏体组织.在所选取的温度和时间范围内,710℃退火保温5 h为最优的退火工艺,等温退火并不能改善钢中带状组织的成分不均.带状组织的形成是由于化学元素Si、Mn、Cr、Ni和Mo的偏聚引起的,提高横截面内变形均匀程度对于改善棒材组织均匀性是有利的,但冶金过程成分偏析均质控制才是减轻或消除带状组织成分不均的关键.     

70Si3Mn钢中无碳化物贝氏体组织及其性能研究

70Si3Mn钢是传统的弹簧钢,其常规热处理工艺是油淬后中温回火得到屈氏体组织。本文对70Si3Mn钢进行等温淬火处理获得无碳化物贝氏体组织,比较了其经不同温度等温淬火处理后的组织与力学性能,并对其耐磨性进行了研究。结果表明,70Si3Mn钢在Ms以上10~30℃等温可得到无碳化物贝氏体组织,该组织由厚度为160 nm的贝氏体铁素体板条和残余奥氏体薄膜组成,它具有较高的强度和硬度、高的塑性和韧性等优异的综合力学性能,同时具有较好的耐磨性。     

低碳锰铌钢控制轧制及轧后快冷的组织与性能

本文研究了06Mn Nb钢中Mn、Nb含量,加热温度、轧制规程、轧后冷却及时效处理等工艺因素与轧后组织性能和断裂行为的关系。降低加热温度,采用合适的轧制规程,轧后在780—600℃之间以17℃/秒冷速冷却,碍到细小的针状铁素体晶粒,细小的M/A岛及少量粒状贝氏体组织的复合组织。提高Mn、Nb含量与加快轧后冷却有相似的作用。这样的组织比控制轧制后空冷的铁素体与珠光体组织,具有更高的σ_Y和好的低温韧性。粒状贝氏体的数量与贝氏体束的尺寸,与加热温度和总形量有很大关系,贝氏体的韧性决定于贝氏体束的大小,大的M/A岛能诱发裂纹。针状铁素体晶柱尺寸,是决定钢的屈服强度与低温韧性的主要因素。     

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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