Cr21节约型双相不锈钢的高温塑性

通过高温拉伸和高温压缩试验研究了两种Cr21节约型双相不锈钢在950～1150℃温度范围内的高温塑性,结果表明两种材料的高温塑性差异很大.通过温度、应变速率、相比例和显微组织4个方面的分析发现,适当增加稳定铁素体相元素和升高变形温度有利于提高Cr21节约型双相不锈钢的高温塑性.在较低温度较高应变速率热变形时,裂纹容易在被拉长的奥氏体和铁素体相界处形核并沿着相界在铁素体内进行扩展.     

热处理对奥氏体不锈钢00 Cr24 Ni13铸坯高温热塑性的影响

采用热处理实验方法,同时结合热模拟压缩和热模拟拉伸试验,研究了热处理对奥氏体不锈钢00Cr24Ni13铸坯高温热塑性的影响。实验结果表明：热处理能够明显改变实验钢铸坯中δ铁素体的形貌;经1200℃保温3 h空冷后,原始铸坯中存在的大面积连续网状δ铁素体完全转变为弥散分布的细小颗粒状组织。具有颗粒状δ铁素体的热处理试样与热处理前相比,不同温度压缩时的变形抗力略有增加,但并没有急剧恶化;热模拟抗拉强度基本保持不变;相同温度下的断面收缩率( Z)显著提高,其中Z≥60%的温度区间由1150~1280℃扩展为1050~1300℃,高塑性(Z≥80%)温度范围在150℃左右(1150~1300℃)。     

冷却速率对奥氏体不锈钢凝固过程影响的原位观察

通过采用激光共聚焦扫描显微镜对AISI304奥氏体不锈钢的凝固过程进行了原位动态观察研究.发现当冷却速率为0.05℃.s-1时,奥氏体不锈钢以胞状晶方式凝固,其凝固模式为FA模式,即δ铁素体相先从液相中形核并长大,γ相在1 448.9℃时通过与液相发生包晶反应（L＋δ→γ）在δ铁素体相界形成,当温度降到1 431.3℃时液相消失,δ铁素体相通过固态相变转变为γ相,富Cr贫Ni的残留铁素体位于胞状晶之间.当冷却速率为3.0℃.s-1时,奥氏体不锈钢以枝晶方式生长,冷却到1346.4℃时包晶反应在液相与δ铁素体相界之间进行,其残留铁素体位于枝晶干,与冷却速率为0.05℃.s-1时相比,其残留铁素体的数量增多,残留铁素体富Cr贫Ni的程度减轻.     

固溶处理温度对2507双相不锈钢组织结构及耐蚀性能的影响

【目的】现代工业的飞速发展对双相不锈钢的使用要求越来越高,为扩大2507双相不锈钢(DSS2507)的实际应用,本研究探讨固溶处理温度对DSS2507组织结构、硬度及耐蚀性能的影响。【方法】通过定量金相法及硬度法研究固溶处理温度对DSS2507显微组织结构以及硬度的影响;通过电化学实验分析固溶处理温度对DSS2507抗腐蚀能力的影响。【结果】随着固溶处理温度的上升,铁素体α相含量增多而奥氏体γ相含量减少,固溶处理温度为1 050~1 100℃时可使钢中铁素体相跟奥氏体相的比例达到1∶1。固溶处理温度为1 000~1 050℃时DSS2507的硬度降低;但固溶处理温度从1 050℃升高到1 200℃时,其硬度又逐渐升高。另外,随着固溶处理温度从1 000℃升高到1 200℃,DSS2507的耐均匀腐蚀和点蚀性能先增强后减弱,1 050℃处理的DSS2507抗电化学腐蚀性能最优。【结论】固溶处理温度为1 050~1 100℃时可以使DSS2507两相比例达到1∶1,经1 050℃固溶处理的DSS2507抗电化学腐蚀性能最优。     

热处理工艺对高碳贝氏体钢组织与力学性能的影响

借助OM、SEM、XRD等手段,对比研究了一步、两步等温贝氏体转变工艺及QPB(淬火+配分+贝氏体转变)工艺对高碳贝氏体钢(w(C)=0.79%)显微组织与力学性能的影响。结果表明,采用一步等温贝氏体转变工艺处理试验钢时,当等温温度同为250℃,随着保温时间的延长,钢中贝氏体转变越充分,块状残余奥氏体尺寸降低,组织更为均匀细小;而在较低温度下(200℃)等温处理时,钢中残余奥氏体含量显著降低,贝氏体铁素体板条更细小,材料的强度和硬度提高,而塑性和韧性下降。两步等温贝氏体转变工艺处理(250℃×24 h+200℃×72 h)的试验钢中贝氏体铁素体板条平均尺寸约为82 nm,残余奥氏体体积分数为21.4%,获得了最佳的综合力学性能,抗拉强度达到2040 MPa,伸长率为12.5%,冲击韧性为21 J。QPB工艺提高了贝氏体转变速率,大大缩短了热处理时间,最终得到马氏体+贝氏体铁素体+残余奥氏体的组织,试验钢同时也获得了良好的强度和塑韧性。     

不同Al质量分数的铸造304不锈钢组织和性能

通过中频无芯感应炉,在无保护气氛的大气中熔炼铸造制备Al质量分数为0%、1.5%、2%、3%的304不锈钢,并对其进行1 050℃,保温45min的固溶处理,利用X射线衍射仪、光学显微镜、电子探针(EPMA)、扫描电镜(SEM)、拉伸试验和腐蚀试验,研究不同Al质量分数304不锈钢的组织和性能.结果表明:304不锈钢中加入Al元素后合金的组织由奥氏体+少量的骨骼状的δ铁素体逐渐转变为奥氏体+铁素体双相组织,当含Al质量分数为3.0%时,304不锈钢的基体组织转变为铁素体和在铁素体晶界上分布着的少量奥氏体.固溶态高铝304不锈钢的性能优于铸态性能,含Al质量分数1.5%的固溶态304不锈钢具有最优的力学性能和耐腐蚀性能,与未加铝的304相比,各种性能均得到较大提高.     

热处理对奥氏体不锈钢00Cr18Ni10N组织和性能的影响

通过对新型奥氏体不锈钢00Cr18Ni10N的热处理工艺试验,研究了不同固溶温度、冷却方式和保温时间对其组织性能的影响.结果表明,随着固溶温度的升高,00Cr18Ni10N钢晶粒变大,力学性能降低,塑性提高.随着保温时间的延长,拉伸强度、屈服强度和硬度都有所降低,断后伸长率略有提高,冲击韧性和断面收缩率变化并不显著.虽然冷却方式对其力学性能和晶粒大小的影响并不是很明显,但在1050℃淬火,采用水冷可以到达更好的综合性能.因此,00Cr18Ni10N钢采用1050℃固溶、保温1h后水冷的热处理工艺具有良好的组织和强韧性配合.     

5NiCrMo低温钢QLT热处理工艺研究

研究了5NiCrMo低温钢的淬火+临界淬火+回火(QLT)热处理工艺,分析了回火温度对该钢组织和力学性能的影响。结果表明:试验钢经QLT热处理后,形成了回火马氏体、-铁素体与逆转变奥氏体的混合组织。560-640℃回火时,随温度提高,屈服强度降低,100℃冲击功先升高、在620℃回火时达到峰值后降低。深冷后保留的逆转变奥氏体显著影响试验钢的低温韧性。拉伸和冲击性能均满足要求的回火温度是600-620℃。     

304奥氏体不锈钢的热处理工艺研究

本文研究了不同热处理工艺对304奥氏体不锈钢组织和性能的影响。304奥氏体不锈钢试块进行1050℃保温30min固溶处理,分别在水中和在空气中的冷却,结果发现得出组织均为单相奥氏体,水中冷却不锈钢硬度更高,说明水冷后获得更大的内应力。原材料进行650℃保温60min敏化处理和800℃保温60min敏化处理对比得出在800℃保温60min时更容易发生晶间腐蚀。因此,304不锈钢热处理时应避免在敏化温度区间内较高温度停留较长的时间。     

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.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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