CSP低碳微Ti钢中Ti(C,N)的析出行为

通过实验观察及热力学计算,研究了CSP低碳微Ti钢中的Ti(C,N)析出.实验观察到大量15～30nm的Ti(C,N)第二相粒子,它们在铸坯均热保温和前两道次的热轧中析出并长大充分;均热前CSP铸坯中只有很少量尺寸约大于50nm的TiN粒子析出,铸坯中观察不到微米级的大块TiN夹杂.研究结果表明,CSP工艺下粒子析出行为同传统工艺相比发生了变化,所以微量Ti在钢中的作用也有很大不同.     

CSP低碳微皿钢中Ti（C，N）的析出行为

通过实验观察及热力学计算，研究了CSP低碳微Ti钢中的Ti（C，N）析出．实验观察到大量15～30nm的Ti（C，N）第二相粒子，它们在铸坯均热保温和前两道次的热轧中析出并长大充分；均热前CSP铸坯中只有很少量尺寸约大于50nm的TiN粒子析出，铸坯中观察不到微米级的大块TiN夹杂．研究结果表明，CSP工艺下粒子析出行为同传统工艺相比发生了变化，所以微量Ti在钢中的作用也有很大不同．     

轧制工艺对CSP线热轧汽车用高强钢板组织特征的影响

研究了薄板坯连铸连轧(CSP)工艺生产高强度汽车用大梁板的工艺控制参数与力学性能和显微组织间的关系.根据柔性工艺控制的指导思想,在珠钢电炉CSP流程下实现了生产不同级别高强度钢板的柔性轧制工艺.利用扫描电镜和透射电镜研究了其组织和强度差异产生的原因.研究表明,钢板最终组织为多边形铁素体和少量珠光体组成,平均铁索体晶粒尺寸约为3.7～5.6μm;当降低卷取温度,部分渗碳体已破碎成细小的碳化物粒子分布于铁素体基体上,钢板中有少量贝氏体出现.     

CSP工艺生产低碳高强度汽车板力学性能特征及强化机理

研究了珠钢电炉CSP工艺生产低碳高强度汽车梁用钢板ZJ510L生产工艺、组织演变、强化机理与组织性能之间的关系.通过光学显微镜、透射电镜和力学性能实验研究表明:ZJ510L显微组织随着轧制道次和冷却速度的增加而细化,最终铁素体晶粒尺寸约为5～6μm;析出的第二相粒子主要为A12O3,MnS和AlN以及大量的碳化物,尺寸大多在20～150nm之间;成品板强度和延伸率较高,并具有良好的成形性能和低温冲击韧性.细晶强化是ZJ510L钢板的主要强化方式.     

梯度结构中间坯制备超细晶低碳钢的组织特性与强化机理

通过中间坯超快冷工艺,在0.2%C-2%Mn普碳钢中获得表层铁素体和心部马氏体的梯度层状组织,实现了钢板压下量约50%的大变形温轧.大变形马氏体经450℃和530℃退火后,制备出平均晶粒尺寸为0.52μm和0.66μm的超细晶组织.利用扫描电镜(SEM)、电子背散射衍射(EBSD)和准静态拉伸试验等手段,研究了超细晶钢板的微观组织与力学性能.结果表明,相较于610℃退火粗晶钢板,450℃和530℃退火超细晶钢的屈服强度可提升2～3倍,平均屈服强度分别达到了1 475 MPa和1 196 MPa,延伸率也显著下降.晶界强化和位错强化是超细晶钢强度提升的主要强化机制,而加工硬化率降低导致了超细晶钢的塑性下降.     

Cr17Mn6Ni4Cu2N奥氏体不锈钢连铸坯组织及凝固模式

采用AOD+LF精炼工艺冶炼,通过连铸工艺生产出Cr17Mn6Ni4Cu2N奥氏体不锈钢连铸坯,对其表面层和中心区域进行金相组织分析,并用电子探针分析组织中化学成分的变化.结果表明,连铸坯表面层上的组织均为在奥氏体基体上分布着不同形态的残余δ铁素体,由表及里δ铁素体的形态分别为骨架形,侧板条状和蠕虫状.根据组织形态确定出这种钢在连铸过程中的凝固模式为从液相中先析出δ铁素体,随后通过固相转变形成奥氏体.由连铸坯表面层铁素体的二次枝晶间距得到冷却速度,分析出冷却速度在5～20 ℃/s变化对凝固模式没有影响.     

中温压力容器钢12CrMo的高温塑性研究

通过热模拟试验对中温压力容器钢12CrMo连铸坯的高温塑性进行研究.在不同的变形温度下采用10-3 s-1的应变速率对试样进行拉伸变形,测量拉伸断口的面缩率,并对拉伸断口的显微组织和析出物进行分析.结果表明, 当变形温度高于900 ℃时,试样在拉伸过程中发生动态再结晶,其面缩率大于85%,表现出优良的高温塑性;当变形温度为850 ℃时,有大量细小的AlN在12CrMo钢中弥散析出,其尺寸约为10 nm;当变形温度降至800 ℃时,大量的先共析铁素体沿奥氏体晶界析出,形成网状结构,试样面缩率降至36%,12CrMo钢的高温塑性显著下降.     

CSP生产Ti微合金化高强钢中纳米碳化物

采用光学金相、电子显微术和化学相分析的方法并结合热力学计算,分析了紧凑式带钢生产(CSP)的Ti微合金化高强钢中的析出物及其析出规律.研究发现:高强钢中存在微米尺寸的立方TiN析出和大量纳米尺寸的析出物粒子;钢中MX相(M=Ti,Mo,Cr;X=C,N)的质量分数为0.0927%,其中10 nm以下的析出物占26.9%;均热之前和均热过程TiN已基本全部析出,连轧前TiC不具备析出的热力学条件;降低钢中N和S含量、严格控制卷取温度可增加TiC的体积分数,降低γ→α相变温度可以阻止细小碳化物长大.结果表明,析出物总的沉淀强化效果约为156 MPa,并能通过化学成分和工艺的控制进一步增强.     

Ti对高强耐候钢力学性能的影响

通过光学显微镜、透射电镜(TEM)以及力学性能测试等手段分析了薄板坯连铸连轧(TSCR)工艺生产Ti微合金化高强耐候钢的成分及工艺对显微组织和力学性能的影响.研究结果表明:钢中加入Ti,屈服强度有明显的提高;钛质量分数为0.05%～0.08%时,高强耐候钢的晶粒尺寸随着钛含量的增加基本不变;高强耐候钢强度的提高主要取决于钢中有效钛的含量,有效钛不仅与钛的含量有关,而且还与S, N的含量有关;在有效钛含量一定的条件下,析出强化的大小主要取决于轧后的卷取温度.     

X70针状铁素体管线钢析出相

用透射电镜研究了X70针状铁素体管线钢中的析出相.一种是以TiN为主、尺寸较大(50nm～1μm)、外形规则、几乎呈立方体的Ti(Nb)NC复合析出相,其中Ti/Nb比值处于5～12之间.另一种是以NbC为主、尺寸十分细小(小于20nm)、形态为圆形或椭圆形的Nb(Ti)C复合析出相,Nb/Ti比值处于1～6.37之间,衍射分析结果表明其为多晶粒构成.分析表明,尺寸较大的方形析出相在1150℃的温度时已经存在,并且在热模拟过程中变化不大.细小圆形析出相绝大部分是在1100～900℃之间析出,而且与基体保持共格或半共格的关系.V的析出不明显,其作用相对较弱.高温热塑性曲线的测量结果显示,在没有变形情况下,1050℃时析出相开始析出,900～850℃之间析出量达到最大.     

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     

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

正~~     

Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has