初始组织形态对中碳钢温变形组织演变的影响

中碳钢温变形过程的组织演变包含铁素体动态回复、再结晶和渗碳体的析出球化等过程.采用Gleeble1500热模拟试验机研究了初始组织形态对含碳0.48%(质量分数)的中碳钢在温变形中上述复杂过程的影响.结果表明:初始组织为珠光体 先共析铁素体的试样在温加工变形中渗碳体层片发生了扭折、溶断到逐渐球化的过程,在铁素体回复再结晶的同时伴随着细小弥散的渗碳体颗粒从过饱和铁素体中析出,得到微米级铁素体晶粒和颗粒状渗碳体弥散分布的复相组织,但等轴状铁素体晶粒与弥散的渗碳体颗粒沿变形方向呈带状不均匀分布.温加工变形促进初始组织为马氏体的中碳钢中渗碳体析出和铁素体回复与再结晶.由于初始条件下碳的分布在微观尺度下相对均匀,变形后获得细小等轴铁素体与均匀分布颗粒状渗碳体的组织.     

形变对板条马氏体回火组织的影响

对Q235级低碳钢板条马氏体在550 ℃多道次单向压缩变形后退火和室温大塑性变形轧制后在此温度退火的显微组织演变规律进行了对比研究,结合未变形板条马氏体在此温度的回火组织演变,讨论了变形对马氏体分解过程、铁素体再结晶晶粒尺寸和析出碳化物形貌的影响. 实验结果表明,变形显著影响马氏体分解过程,促进渗碳体的析出和铁素体回复及再结晶. 热变形组织铁素体再结晶晶粒尺寸在0.5 μm左右;渗碳体形貌从细棒状向球状转变,随变形量增大渗碳体尺寸增大,继续保温60 min导致铁素体晶粒长大到1 μm左右,晶粒内部的渗碳体消失,原先在铁素体晶界析出的渗碳体球化、粗化. 冷轧试样在550 ℃退火保温时间在30 min内得到0.3～0.4 μm超细晶粒和尺度小于150 nm的弥散渗碳体颗粒组织;随退火保温时间延长到60 min,铁素体再结晶晶粒长大到1.9 μm,渗碳体颗粒尺寸约160 nm.     

冷轧退火对共析珠光体钢组织球化超细化的影响

研究了冷轧变形并结合退火处理对共析钢组织球化超细化与性能的影响.结果表明:共析钢经冷轧形变量90%结合600～700 ℃退火得到了晶粒尺寸为亚微米级铁素体晶粒和颗粒状渗碳体的双相组织.颗粒状渗碳体的尺寸呈双峰分布.与传统球化处理工艺相比,球化时间明显缩短,球化组织细小;其原因是在冷变形过程中产生了高密度位错以及大量空位等缺陷,为碳原子的扩散提供了高速率扩散通道,促进了碳原子的扩散.细小渗碳体粒子在铁素体基体上的弥散分布可以用溶解-再析出机制来解释.冷轧后经700 ℃退火试样的拉伸塑性略有下降,屈服强度和抗拉强度大幅度提高,但屈强比较高.     

温变形对碳钢组织细化的作用

研究了中温预变形对亚、过共析钢组织的影响。结果表明,对于亚共析钢,在中温区变形、保温后可使先共析铁素体和珠光体组织大大细化,显著改善钢中铁素体和珠光体的分布状况;对于（ 过） 共析钢,中温区预变形则可大大缩短钢的球化时间,改善球化效果,细化组织,特别是对消除钢中的网状组织具有明显的效果。     

GCr15钢温变形对球化退火的影响

研究了 GCr15 钢的温变形对球化退火的影响。结果表明:珠光体温变形显著加快了碳化物球化过程。随变形量、变形速度的增加及变形温度的降低,球化速度增加,变形量是影响球化速度最显著的参数。珠光体的温变形促进了在790℃加热、保温过程中渗碳体的溶解和未溶渗碳体粒子的圆整过程。还对温变形试样快速球化退火工艺进行了试验。     

中碳钢温变形的力学特性

利用Gleeble-3500热模拟实验机对中碳钢铁素体+珠光体组织进行温变形压缩试验,研究其在不同变形温度(500～700 ℃)和应变率(0.001～10 s-1)条件下的流变行为及其主导机制. 研究结果表明:温变形过程先从铁素体变形开始,而后珠光体开始变形,渗碳体片层结构被破坏;铁素体晶粒细化至1～2 μm;珠光体片层被破坏使流变应力形成峰值;温变形流变应力曲线特征具有显著差异性,对工件塑性成形、工模具载荷分布及变形产生重要影响.      

铌对中碳Si-Mn系弹簧钢珠光体相变行为的影响

采用热模拟实验方法研究了铌对Si--Mn系弹簧钢相变特征的影响,分析了NbC的形变诱导析出行为.结果表明:弹簧钢中添加微量铌,推迟了珠光体转变,马氏体转变的最小冷却速率由5℃.s-1变为3℃.s-1;细化了珠光体,改变了珠光体组织形貌,渗碳体片层变薄、形状变得不规则,出现弯曲、断续;含铌弹簧钢在850℃变形时发生了NbC的形变诱导析出,NbC的析出位置为珠光体中的铁素体片层内、珠光体球团边界和位错处,析出物颗粒直径为10～15nm,形状近似球形.     

T10A钢锻造后的预处理工艺

本文主要介绍了T10A钢锻造以后的预先热处理工艺方法.结果表明,通过提高锻造以后的冷却速度,可以有效的细化珠光体基体组织,抑制网状二次渗碳体的析出,有效的细化渗碳体颗粒,同时,可适当降低球化退火时的加热温度,减少保温时间,降低生产成本,提高生产效率.     

不同工艺下Nb-Ti微合金钢组织演变和析出行为

利用Gleeble 3800热模拟实验机、透射电镜和纳米压痕仪器等研究了终冷温度和保温时间对Nb-Ti微合金钢组织、析出行为的影响规律.结果表明:随终冷温度的升高,铁素体晶粒尺寸增大,珠光体增多,贝氏体逐渐减少,维氏显微硬度随终冷温度先升高后降低,当终冷温度为640℃时,实验钢的维氏显微硬度最大;当终冷温度为640℃时,试样中存在排列规则的相间析出和弥散分布的随机析出两种析出形式.当保温时间为0s时,析出物以相间析出和弥散析出为主;当保温时间为100s时,析出物以弥散析出为主.随保温时间增加,实验钢的纳米硬度降低了140MPa.     

低碳钢中超细铁素体的长大倾向

在热模拟单向压缩条件下考察了四个不同C,Mn含量的低碳钢中通过形变强化相变产生的超细铁素体在模拟卷取温度下的长大倾向.结果表明,不同C,Mn含量的四种钢中的超细铁索体在～500℃的保温0～10min过程中都很稳定,没有明显的长大过程,也未明显观察到铁素体的静态再结晶.超细铁素体稳定的主要原因是由于稳定的第二组织(珠光体或渗碳体颗粒)的有效钉扎,它既阻止了铁素体的明显长大,也抑制其静态再结晶的充分进行.但不同C,Mn含量的四种钢中的第二组织有不同的演变规律,保温过程中形变奥氏体内形成离异珠光体并缓慢粗化.另外,利用背散射电子衍射取向成像技术还测定了08钢保温过程中的取向(差)变化.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.