首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
采用热模拟方法研究了薄板坯连铸连轧工艺生产无间隙原子钢的动态及静态相变规律,绘制其动态与静态连续冷却转变曲线;并比较分析薄板坯连铸连轧工艺下无间隙原子钢在变形及不变形条件下的相变温度及组织演变规律。  相似文献   

2.
E36船板钢连续冷却转变行为研究   总被引:3,自引:0,他引:3  
在THERMECMASTOR-Z热模拟实验机上测定了E36船板钢的连续冷却转变曲线,利用光学显微镜对钢组织进行了观察,并利用维氏硬度计对E36钢硬度进行了测定.结果表明,试验钢奥氏体向铁素体转变温度在785~590℃范围内.当冷却速率小于20℃/s时,随着冷却速率的增快,E36钢晶粒度增加较为明显;而当冷却速率大于20℃/s时,E36钢晶粒度变化趋于平缓.当冷却速率小于20℃/s和大于60℃/s时,E36钢维氏硬度值增加较大;而当冷却速率在20~60℃/s范围时,E36钢维氏硬度的变化趋于平缓.  相似文献   

3.
以FH40高强度级别船板钢为研究对象,利用真空感应炉冶炼了不同Mg、Zr成分的实验钢,采用Gleeble-3800热模拟试验机测定了实验钢连续冷却转变曲线(CCT)。采用金相显微镜系统研究了实验钢连续冷却条件下的组织演变规律,并探讨了Mg、Zr单独和复合添加对实验钢CCT曲线中铁素体和贝氏体相区的作用规律。结果表明,Mg、Zr及Mg-Zr添加均能影响过冷奥氏体和珠光体开始转变温度;Mg和Mg-Zr添加抑制了铁素体转变,促进了贝氏体转变,在5~30℃/s冷却速度范围内均获得以贝氏体为主的组织;Zr添加扩大了铁素体区,减小了贝氏体区,冷却速度提高至20℃/s以上可得到以贝氏体为主的组织。研究结果对进一步明确Mg、Zr对低碳微合金钢组织特征的作用规律,指导Mg、Zr及Mg-Zr处理在工业上的应用具有重要意义。  相似文献   

4.
为开发一种新的低成本高性能含B钒微合金钢和建立其TMCP生产工艺,用MMS-200热力模拟试验机研究了实验钢在连续冷却条件下的相变规律,绘制出实验钢的静态CCT曲线和动态CCT曲线.结果表明:微量的B提高了钒微合金钢过冷奥氏体稳定性,促进了针状铁素体形成,在比较宽的冷却速度范围内能得到贝氏体组织;未变形钢相比于变形钢,在更低的冷却速度甚至0.5℃/s的冷却速度下能得到大部分的贝氏体组织,但两者在5℃/s以上的冷却速度下都得到全部贝氏体组织;变形降低了奥氏体稳定性,促进铁素体转变,含硼钢铁素体转变存在的冷速升高到2℃/s,不含硼钢的其冷速升高到15℃/s;钒微合金钢中B有利于获得高强度的贝氏体组织,冷速5℃/s以上时相变后含硼钢的硬度都高于变形及未变形不含硼钢的硬度.  相似文献   

5.
72A帘线钢连续冷却转变规律的分析   总被引:2,自引:1,他引:1  
采用热膨胀法在Gleeble-1500热模拟实验机上测定72A帘线钢的连续冷却转变(CCT)曲线,并分析开始冷却温度为900 ℃时不同冷却速度下帘线钢的室温组织和连续冷却转变规律.结果表明,随着冷却速度的加快,72A帘线钢的转变开始温度降低、完成转变时间缩短、珠光体片层间距变细,但连续冷却转变条件下得到钢中珠光体组织的均匀性较差.  相似文献   

6.
铌钒微合金化高强度船板钢的连续冷却转变规律   总被引:1,自引:0,他引:1  
利用相变仪和热模拟试验机模拟现场生产工艺条件测定了一种铌钒微合金化高强度船板钢的静态和经三种终轧温度变形后的动态连续冷却转变(CCT)曲线.结果表明:同静态CCT曲线比较,实验钢的动态CCT曲线整体向左上方移动.随冷却速度的增大,实验钢的γ/α相变开始温度逐渐降低;贝氏体相变开始温度Bs先升高到一个平台,随冷却速度的进一步增加又降低;铁素体晶粒细化.终轧温度自900降至800℃,动态CCT曲线的γ/α相变开始温度及贝氏体上临界冷却速度轻微增加,Bs下降10℃左右,晶粒细化.  相似文献   

7.
TSCR生产800 MPa级TRIP钢的连续冷却相变及组织演变模拟   总被引:3,自引:0,他引:3  
采用热模拟试验机Gleeble-2000,研究了薄板坯连铸连轧工艺条件下TRIP钢连续冷却转变规律及其组织演变.结果表明:实验钢的相变开始温度较低且随着冷却速度的增大而下降,有利于低温终轧;高温加热抑制相变而变形则促进相变;同时当冷却速度大于10℃时,开始出现贝氏体转变.  相似文献   

8.
P460NL1钢的焊接热影响区粗晶区组织和性能   总被引:1,自引:0,他引:1  
利用焊接热模拟手段和冲击实验方法研究了国产新型低合金高强钢P460NL1焊接热影响区(HAZ)粗晶区的组织和性能在连续冷却转变过程中的变化,发现随着800℃到500℃冷却时间(t8/5)的增加,该区的组织、性能都随之而发生变化,当t8/520s,t8/5<60s时,热影响区粗晶区组织为羽毛状上贝氏体、铁素体,其性能逐渐变坏·因而在实际生产中建议严格限制使用大的焊接线能量,以确保焊接热影响区的机械性能·  相似文献   

9.
利用热模拟试验测定耐火钢Q420FRE在不同焊接热循环下的热膨胀曲线,结合显微组织观察及硬度测试结果,绘制其焊接热影响区的连续冷却转变(SH-CCT)曲线,分析t_(8/5)(从800℃到500℃的冷却时间)对试验钢组织、硬度及相转变速率的影响。结果表明,在较大的t8/5范围内,Q420FRE钢热影响区组织均以贝氏体为主,硬度(HV0.2)变化范围为185~208,与母材基本相当;试验钢具有较高的贝氏体转变温度,随着t8/5的减小(除50、80s外),即冷却速率的增加,贝氏体相变开始温度和结束温度逐渐降低,相变速率增大,相变温度区间变化不明显;当t_(8/5)为50、80s时,相变速率有所降低,相变温度区间稍有增大。  相似文献   

10.
用MMS-200热力模拟试验机研究了含钒汽车大梁钢P510L在连续冷却条件下的组织演变规律,采用热膨胀法结合金相法建立了P510L的静态CCT曲线和动态CCT曲线,分析了变形条件、冷却速度对P510L显微组织的影响.结果表明:奥氏体低温区的变形促进了铁素体相变和珠光体相变,抑制了贝氏体相变;并且随着冷却速度的增大,铁素体的量减少,贝氏体的量增多.  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
王慧 《科技信息》2008,(10):240-240
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.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

18.
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。  相似文献   

19.
1 Rise of studies on climate change's effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America's annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].  相似文献   

20.
The concept of nanopore analysis, using the pore-forming protein a-hemolysin to detect individual nucleic acids at a single-molecule level, was first proposed in 1996. Over the past two decades, tremendous progress has been made in the nanopore field, and nanopore analysis has become a label-free and high-throughput method for probing bio- molecules and other analytes with single-molecule sensi- tivity, especially holds the promising for "third generation" DNA sequencing. However, challenges still remain in the experimental strategies and the design of whole nanopore-based instruments. Here, we proudly present a special topic dedicated to the topic of "Nanopore Analysis", with 8 reviews/articles providing up to date coverage of the experimental strategies, theoretical calcu- lations and simulations, and instrument design. Reviews and articles on the experimental strategies cover control of DNA partitioning into a nanopore, detection of target DNA, and the advantages of nanopore-based DNA sequencing. The theoretical calculations and simulations discuss the translocation behavior of DNA, and an inte- grated measurement system and data analysis software are presented for instrument design.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号