含Nb船板钢再结晶行为及控轧工艺研究

在Φ450轧机上对含Nb船板钢进行阶梯轧制,研究不同变形温度和变形量下高温奥氏体再结晶行为,绘制出奥氏体形变再结晶区域图,根据再结晶区域图进行热轧实验,通过两种不同的控轧工艺实验对比,寻求力学性能稳定的含Nb船板钢控轧工艺。结果表明,变形温度为1000℃,20%的变形量可发生奥氏体再结晶;变形温度为900℃,低于30%的变形量不发生奥氏体再结晶,变形量增大至40%～50%,发生部分奥氏体再结晶;变形温度为850℃,50%的变形量也不发生奥氏体再结晶。终轧温度提高至910℃,利用超快速冷却技术,合理控制精轧阶段的变形量,可使含Nb船板钢获得与低温终轧条件相当的力学性能。     

30SiMnCrB5热成形钢的微观组织和力学性能

为了提高热成形钢的综合性能,设计了一种C-Si-Mn-Cr-B系热成形钢,采用热膨胀仪测定并研究了30Si Mn Cr B5热成形钢的连续冷却转变曲线和相变规律.分析了经轧制、退火及热成形模拟后钢板的微观组织形貌和力学性能,结合等密度线极图的方法,判定了热成形模拟后钢板中马氏体变体与母相的取向关系.30Si Mn Cr B5热成形钢具有较好的淬透性,临界冷速为5℃·s-1,有效抑制了珠光体和贝氏体的形成,完全马氏体组织的硬度可达600 HV以上.热成形模拟后的微观组织由板条马氏体和残余奥氏体构成,残余奥氏体主要以薄膜状分布在马氏体板条间,质量分数为6%~8%,抗拉强度为1800 MPa左右,总伸长率可达10%以上,强度和塑性的匹配较好.热成形模拟后30Si Mn Cr B5热成形钢板中马氏体变体与母相的取向关系更接近N-W关系,12种变体没有都出现在原始奥氏体内.     

超快速冷却工艺对中低碳钢组织性能的影响

基于UFC-ACC设计理念,结合超快速冷却机理及其在中厚板产品处理过程中的技术实现,针对中低碳钢采用不同轧制方式,分析超快冷后钢板力学性能变化,得出较优超快冷冷却规程;同时,对比不同工艺条件下的金相组织,结合理论计算,总结出超快速冷却条件下中低碳钢组织性能演变规律.从分析结果看,中低碳钢冲击韧性明显提高,其他力学性能也有较大改善;此外,UFC-ACC冷后机体大部分为细小均匀的F+P组织,并能保持原奥氏体中的高密度位错,使钢板性能优于普通ACC处理后钢板.     

Q390高强低合金厚板控制轧制工艺

通过模拟实验研究了控制轧制工艺对Q390高强度低合金厚板结构用钢显微组织和力学性能的影响;通过组织分析和力学性能检测表明采用本研究所设定的控制轧制工艺试验轧制的50 mm厚板,其Rm>517 MPa,ReL>382 MPa,韧脆转变温度介于-60℃至-70℃之间,达到了GB/T1591—94的要求.在Nb(C,N)完全固溶温度以下保温有利于提高钢板的低温韧性;在相同的精轧总压下量和空冷制度下,轧制道次及介于830~780℃的终轧温度对于钢板的组织性能影响不大.     

微碳钢铁素体区热轧试验研究

在连铸连轧生产线采用铁素体轧制技术制备微碳钢热轧薄板,并对所制备薄板的组织、性能及织构进行分析。结果表明:铁素体轧制微碳钢热轧薄板的组织为完全再结晶铁素体,平均晶粒尺寸50 m左右。相对于常规奥氏体轧制,铁素体轧制薄板的屈服强度和抗拉强度分别下降了21%和6%,延伸率略有下降。热轧薄板的塑性应变比值为0.4,明显低于常规奥氏体轧制。薄板中存在较强的{001}织构是导致值较低的主要原因。     

真空轧制不锈钢复合板的组织和性能

采用真空轧制法对6mm厚的奥氏体不锈钢板和50mm厚的碳钢板复合.在高真空、高温和大轧制力的共同作用下,界面实现了牢固的冶金结合并且最终得到了高质量的不锈钢复合板.研究发现界面无开裂和氧化层,仅在界面附近分布少量细小弥散的Si-Mn氧化物颗粒.通过能谱发现不锈钢侧的Cr和Ni向碳钢迁移,在界面形成一薄层富Cr,Ni层,导致复合层硬度升高;碳钢中的C向不锈钢侧迁移导致出现脱碳区,且该区硬度最低.界面的剪切强度达467MPa.     

淬火-回火工艺对X80管件钢组织性能的影响

采用扫描电子显微镜(SEM)、电子背散射衍射分析技术(EBSD)和透射电子显微镜(TEM)等实验手段,研究了不同淬火--回火热处理工艺制度对X80管件钢组织性能的影响.结果表明:一次930℃淬火后,随着回火温度的升高,实验钢屈服强度先升高后降低,在630℃达到最大值588MPa;抗拉强度随回火温度升高持续下降,680℃时降至630MPa.二次两相区淬火,经630℃回火后,X80管件钢有最佳的综合力学性能,-50℃冲击韧性显著提高,Ak达到210J.这是由于二次淬火温度在860℃两相区时,组织中奥氏体晶粒大幅细化,经630℃回火后,细晶马氏体组织中出现位错亚结构的回复软化、板条边界钝化和块状M-A组元分解产生的析出强化机制综合作用的结果.     

超快冷工艺对钢板心部异常带状组织的抑制作用

采用OM、TEM和EMPA方法对比研究了超快冷工艺及终轧温度对355 MPa级钢板心部异常带状组织的影响.结果表明,950℃高温终轧及超快冷钢板(UC1钢)心部带状组织完全消失,900℃终轧及超快冷钢板(UC2钢)心部则形成了微弱带状组织,而轧后15℃/s层流冷却钢板(LC钢)心部则形成了包括马氏体/奥氏体低温相的严重带状组织.热力学计算显示,钢板心部偏析降低铁素体相变温度144℃,从而提高消除带状组织所需临界冷速到8℃/s.温度计算得到UC1和UC2钢板心部冷速分别达12.1和13.4℃/s,而LC钢板心部冷速只有5.5℃/s,表明超快冷足以抑制心部带状组织,但降低终轧温度削弱了这个效果,而层流冷速则无法抑制带状组织.     

终轧和终冷温度对X65/X70中厚板管线钢屈强比的影响

通过对不同终轧、终冷温度条件下X65/X70中厚板管线钢的板屈强比值和微观组织的变化研究发现,当终轧温度低于Ar3温度时,钢板进入两相区轧制,钢板组织呈带状分布,钢板屈服强度的提高幅度大于抗拉强度的提高,屈强比呈上升趋势.水冷中钢板头部温度过冷对屈强比控制也非常不利.通过对X65/X70管线钢进行控轧控冷工艺优化,屈强比值得到显著降低,大幅提高了管线钢板合格率和成材率.     

V-N微合金化X80抗大变形管线钢的组织与力学性能

通过热模拟试验机研究了V-N微合金钢过冷奥氏体动态连续冷却相变行为,设计了V-N微合金化X80抗大变形管线钢的轧制与冷却工艺参数并分析了组织和力学性能的关系.结果表明,动态CCT曲线出现高温转变区和中温转变区分离的现象,转变温度范围分别是637~728℃和441~601℃,当冷速为10~20℃/s时,形成针状铁素体为主的组织.V-N微合金化管线钢组织以多边形铁素体和针状铁素体为主,屈服强度、抗拉强度、均匀延伸率和-20℃夏比冲击功分别为603MPa,724MPa,11.1%和214J,满足API Spec 5L对X80管线钢的力学性能要求,同时具有好的强塑性匹配.     

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     

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