An Experimental Study on Constraint Cooling Process of Hot-rolled CoilS

In order to master mechanical property, surface quality and microstructure of constraint cooling (CC) coils undervarious water cooling parameters, more than 100 coils cooling experiments were done with real production process,of which is designed a cooling experimental instrument in the end. The experiments show that high initial coolingtemperature, discontinuous cooling style, and long cooling time can improve mechanical property of cooling coilsand shorten cooling time. The CC coils experiments cover the different steel grades, so that CC process effects onhot-rolled coils may be predicted and controlled actively.

Improvement in Production Yield of Hot-rolled Coil by Controlling Process Cobbles

The yield is dependent upon many factors,such as cobbles,total scrap generation,crop loss and scale loss.It appears that the huge quantity of scale is mainly responsible for the yield loss.However,by the correlation study,it reveals that the number of cobbles is the major contributor to the yield loss.The innovation lies in changing the focus of attacking the real problem by analysing the operating data which was not surfaced earlier.The focus shifted from the furnace to the mill and the cobbles studied through the years deeply.All the analysis proved to be helpful for the future prevention of the similar kind of failure.The internal target of bringing down the number of cobbles per month in single digit was taken.This also helped in improving the maintenance practice and reducing the amount of delays significantly.The yield was improved by 0.93%.

基于线粒体COI序列片段研究华鳈不同地理群体及其他鳈属鱼类的遗传多样性

鳈属(Sarcocheilichthys)鱼类是东亚地区常见小型淡水鱼类,并具有一定的养殖开发潜力。深入了解鳈属鱼类的遗传结构及其地域变异,对科学制定保护计划和可持续利用野生资源具有重要意义。试验采用鳈属鱼类包括小鳈(S.parvus,XQ)20尾,江西鳈(S.kiangsiensis,JXQ)20尾,黑鳍鳈(S.nigripinnis,HQQ)20尾,东北鳈(S.lacustris,DBQ)24尾,华鳈(S.sinensis)淮河群体(HQ_(HH))20尾、闽江群体(HQ_(MJ))17尾、江西群体(HQ_(JX))15尾和建德群体(HQ_(JD))17尾,并对每个群体的线粒体细胞色素C氧化酶亚基Ⅰ(cytochrome C oxidase subunitⅠ,COI)序列片段进行了测序和分析。试验结果表明,在获得的153个样本序列(668 bp)中,保守位点507个,变异位点154个,简约信息位点150个,碱基缺失或插入位点27个,平均转换与颠换比值为5.2。HQQ群体的单倍型多样性(Hd)最低(0.442),HQHH群体的Hd略高于HQQ群体(0.574),DBQ群体的Hd则稍高于HQHH群体(0.707),而XQ群体的Hd最高(0.963),HQMJ和HQJX群体的Hd则略低于XQ群体(0.860、0.848)。核苷酸多样变化趋势则与Hd结果类似。153尾个体定义了56种单倍型,各群体的单倍型网络中均存在各自群体的主要单倍型,如Hap_2、Hap_33和Hap_37等。基于遗传距离构建的UPGMA分子系统发育树、层次聚类树和NeighborNet分子系统发育网络表明,XQ、HQQ、JXQ和其他鳈属鱼类间遗传关系较远,而DBQ与HQHH群体间遗传关系较近。该研究利用COI序列片段评估了4个华鳈地理群体及其他4种鳈属鱼类的遗传多样性。研究结果将有助于了解华鳈不同地理群体及其他4种鳈属鱼类野生资源的遗传多样性现状,为今后华鳈以及其他4种鳈属鱼类种质资源保护及利用提供参考。

“Quartus scale” of hot-rolled strip steels and its formation mechanism

The types and growth of various oxide scales formed during the different phases of the production of hotrolled strip steel products are reviewed. Similarities and differences between the ＂tertiary scale＂ on the surface of carbon steels at high temperatures and the oxide scale on pure iron are compared. The micro-structural features of the ＂final oxide scale＂ on the surface of strip steels at room temperature as well as the relationship between these features and the position of the steel coil （plate） and the subsequent processes of recoiling, temper rolling and trimming, etc. are summarized. The actual oxide scales retained on the commercial hot-rolled strip steels at room temperature have been proposed to define as ＂ quartus scale＂ for the first time. The micro-structural development and phase transformation of the initial ＂tertiary scale＂ during and after cooling and coiling are described. The reasons for the ＂tertiary scale＂ on carbon steels differing from the oxide scale formed on pure iron, and the major influencing factors in the formation of various types of ＂quartus scales＂ are analyzed from both thermodynamic and dynamic viewpoints. The development mechanism of ＂ quartus scales＂ is discussed and the potential effects of the ＂ quartus scale＂ state （thickness, constitution, structure and defects）, on the rusting and pickling properties of commercial hot-rolled strip steel, as well as on the mechanical properties of oxide scales are analyzed.

Microstructures and Mechanical Properties of Nb-Ti Bearing Hot-rolled TRIP Steels

Nb-Tihot-rolled TRIP-assisted steel with high plasticity and appropriate volume percentage of retained austenite based on fine ferrite grain have been developed in the experiment. The test results showed that niobium tend to exist in solution state in matrix with less precipitation, and niobium-titanium could be precipitated in form of （Nb, Ti）C or （Nb, Ti） （C, N）, which play an important role in increasing yield strength （from 495 MPa to 610 MPa）. Besides, the retained austenite had a positive effect on improving the plasticity by transformation into martensite during tensile deformation.

基于形态特征、COI基因序列和杂交试验的云南茶园小绿叶蝉种类鉴定

【目的】前期研究发现,云南普洱茶园的小绿叶蝉与我国其他产茶省茶园的小贯小绿叶蝉Empoasca(Matsumurasca)onukii形态相似,但阳茎形态略有差别。本研究旨在明确云南茶园发生的小绿叶蝉是否为小贯小绿叶蝉,以期为云南茶园小绿叶蝉防治提供科学依据。【方法】采集了云南4市11区/县13个茶园的小绿叶蝉样品和贵州省1个茶园、浙江省2个茶园的小贯小绿叶蝉样品。通过形态学观察、COI基因序列比对和杂交试验,以明确云南省茶园发生的小绿叶蝉种类。【结果】云南省13个茶园采集的小绿叶蝉样品雄虫阳茎干基腹面均具一刺突,而贵州和浙江省小贯小绿叶蝉样品无此特征。云南13个茶园的小绿叶蝉COI基因序列NCBI上的搜索结果与E.(M.)onukii的COI序列的一致性在99.35%~99.74%;16个采样地的小绿叶蝉遗传距离两两比对在0.000~0.011;单倍型丰度聚类分析显示,云南的样品单独成支,贵州和浙江的样品聚集为一支。云南普洱茶园小绿叶蝉的雌雄成虫与浙江杭州小贯小绿叶蝉可自然发生交配,并产生可育的F_(1)代。两种群间无生殖隔离。正反杂交F_(1)代的孵化率、羽化率、若虫历期无显著差异。F_(1)自交的F 2代其单雌产卵量、羽化率、雌雄比和若虫历期无显著差异。【结论】云南茶园发生的小绿叶蝉为小贯小绿叶蝉E.(M.)onukii,我国茶园中的小贯小绿叶蝉已经分化出不同形态特征的地理种群。

Research on Retained Austenite for Advanced Aluminum-containing Hot-rolled TRIP Steel

A new type of hot-rolled transformation induced plasticity （TRIP） steel with 2.3%AI was developed to replace conventional Si-bearing TRIP steel to improve surface quality of the steel sheet. The relationship between retained austenite volume fraction and hot-rolling processing was researched by Gleeble-2000 thermo-dynamic test for the Al-bearing steel. The experimental result showed that aluminum played an important role on retaining austenite and the volume fraction increased from 4.4% to 7.5% as coiling temperature increased from 350℃ to 450℃, while coiling temperature had a stronger effect on retaining austenite than finishing rolling temoerature.

Effect of Reduction on Bonding Interface of Hot-rolled Wear-resistant Steel BTW1/Q345R Cladding Plate

Wear-resistant cladding plates consisting of a substrate（Q345 R） and a clad layer（BTW1） were bonded through hot rolling at the temperature of 1 200 ℃ and a rolling speed of 0.5 m/s. The microhardness of the cladding plate was also tested after being heat treated. The microstructure evolution on the interface of BTW1/Q345 R sheets under various reduction rates was investigated with a scanning electron microscope（SEM） and EBSD. It is found that the micro-cracks and oxide films on the interface disappear when the reduction is 80%, whereas the maximum uniform diffusion distance reaches 10 μm. As a result, a wide range of metallurgical bonding layers forms, which indicates an improved combination between the BTW1 and the Q345 R. Additionally, it is discovered that the unbroken oxide films on the interface are composed of Mn, Si or Cr at the reductions of 50% and 65%. The SEM fractography of tensile specimen demonstrates that the BTW1 has significant dimple characteristics and possesses lower-sized dimples with the increment in reduction, suggesting that the toughness and bonding strength of the cladding plates would be improved by the increase of reduction. The results reveal that a high rolling reduction causes the interfacial oxide film broken and further forms a higher-sized composite metallurgical bonding interface. The peak microhardness is achieved near the interface.

Properties,Microstructures and Precipitate Morphology of Hot-rolled Interstital-Free(IF)Steel Sheets

In order to simplify production process and to decrease production cost of thicker cold-rolled iF steel sheets for deep drawing applications, a new hot-rolled IF steel sheet is developed through hot-rolling in or region. In this paper, properties, microstructures and precipitate morphology of hot-rolled iF steel sheets are described..

Deep learning for predictive mechanical properties of hot-rolled strip in complex manufacturing systems

Higher requirements for the accuracy of relevant models are put throughout the transformation and upgrade of the iron and steel sector to intelligent production.It has been difficult to meet the needs of the field with the usual prediction model of mechanical properties of hotrolled strip.Insufficient data and difficult parameter adjustment limit deep learning models based on multi-layer networks in practical applications;besides,the limited discrete process parameters used make it impossible to effectively depict the actual strip processing process.In order to solve these problems,this research proposed a new sampling approach for mechanical characteristics input data of hot-rolled strip based on the multi-grained cascade forest(gcForest)framework.According to the characteristics of complex process flow and abnormal sensitivity of process path and parameters to product quality in the hot-rolled strip production,a three-dimensional continuous time series process data sampling method based on time-temperature-deformation was designed.The basic information of strip steel(chemical composition and typical process parameters)is fused with the local process information collected by multi-grained scanning,so that the next link’s input has both local and global features.Furthermore,in the multi-grained scanning structure,a sub sampling scheme with a variable window was designed,so that input data with different dimensions can get output characteristics of the same dimension after passing through the multi-grained scanning structure,allowing the cascade forest structure to be trained normally.Finally,actual production data of three steel grades was used to conduct the experimental evaluation.The results revealed that the gcForest-based mechanical property prediction model outperforms the competition in terms of comprehensive performance,ease of parameter adjustment,and ability to sustain high prediction accuracy with fewer samples.

Hot-rolled strips of up to 19 mm in thickness and their processing to helically welded large diameter pipes of grade X80

Hot-rolled wide strip for production of large diameter,heavy gauged(up to 19 mm) helical line pipe grade X80 was a priority development over the last three years.Microstructure,texture and mechanical properties of strips have been characterised.Also the welding conditions have been simulated.The favourable microstructure is achieved by the proper selection of an appropriate chemical composition of low carbon content and increased niobium micro alloying in combination with suitable strictly controlled hot-rolling parameters.The addition of niobium in combination with the adjustment of other alloying elements increases the recrystallisation stop temperature and thus makes it possible to apply a high temperature processing(HTP) concept.The homogeneous bainitic microstructure across the strip gauge is then formed during accelerated cooling on the run-out table of the hot-rolling mill.All results indicated excellent properties of these hot strips which make it suitable for spiral pipes of grade X80 for example 18.9mm×Φ1 220 mm at dimension.

Rusting behavior and preventative measures of hot-rolled steel plates for automobile applications

As one of the important categories of hot-rolled products, hot-rolled steel plates for automobile applications generally undergo uniform corrosion or localized corrosion according to different environments of manufacturing, transportation and/or storage of the plates. General corrosion often takes place on the surface of a plate in the exterior part of a package, and only reduces the thickness of the plate and slightly increases the roughness of the surface; however, localized corrosion on the surface of a plate inside the package is likely to result in the formation of pit-like defects on the substrate of the plate, which cannot be removed thoroughly by normal acid pickling or sand blasting, and affects the application of the plate. This research report analyzes the phenomena and characteristics of the rusting behavior of hot- rolled steel plates for automobile applications, and the influencing factors are summaried. The corresponding preventative measures are proposed.

基于COI基因的浙江省内黄缘闭壳龟遗传多样性研究

为了解浙江省内不同黄缘闭壳龟(Cuora flavomarginata)群体的种质资源现状,基于线粒体DNA COI序列对来自浙江省内野外和养殖场的8个黄缘闭壳龟群体的遗传多样性和遗传结构进行比较分析。结果表明:黄缘闭壳龟线粒体COI基因序列长度为1040 bp,A=27.4%、T=30.5%、C=24.6%、G=17.5%,有较强的AT偏好性;共定义9个单倍型,单倍型多样性(Hd)为(0.79900±0.21000),核苷酸多样性(Pi)为(0.00209±0.00147),呈“高Hd低Pi”遗传分布;不同黄缘闭壳龟群体间的遗传距离为0~0.003,群体内部的遗传距离为0~0.004,其中磐安后阁村(YS)群体内部的遗传距离最大,为0.004;单倍型系统发育树并未呈现明显的谱系结构;群体间遗传分化指数(FST)为-0.34752~0.82222,8个群体的遗传分化不显著(p>0.05);中性检验(Tajima’s D=-0.36627,Fu’s FS=-0.605)与核苷酸错配分布均表明,浙江省内黄缘闭壳龟群体并未经历种群扩张事件,同时,由Mantel检验可知,遗传距离与地理距离没有显著的相关性(R=0.2938,p>0.05);AMOVA分子方差结果显示,群体内的遗传变异高于群体间(85.06%>14.94%)。研究表明,浙江省内黄缘闭壳龟群体之间为高单倍型多样性和低核苷酸多样性的遗传特征,并且存在一定水平的遗传分化,群体内存在明显的基因交流,根据COI基因分析显示,在磐安县获得的野生黄缘闭壳龟个体确定为黄缘闭壳龟浙江种,同时也发现存在浙江种与安徽种的杂交种,建议将分化程度不同的黄缘闭壳龟群体划分为不同单元保护。研究结果为浙江省内黄缘闭壳龟种质资源开发利用和合理制定保护措施提供了基础依据。

基于COI和16S rRNA基因序列的鱼胶基原鱼种DNA条形码鉴定

目的建立基于COI和16S rRNA基因序列的DNA条形码鱼胶基原鱼种鉴定方法。方法以汕头、厦门、莆田等地采集的28份鱼胶为研究对象,利用形态归类法对28份样品进行观察,再提取基因组DNA,分别利用6对引物扩增COI和16S rRNA基因序列并双向测序。聚合酶链式反应(polymerasechain reaction,PCR)产物测序分析后,输入Genbank中进行BLAST分析比对,再利用最大似然法(maximum likelihood,ML)进行系统发育分析。结果采集的28份鱼胶样品可分为11种类型,主要有萝卜型、“Y”字型、心型、纸片型和琵琶型等。BLAST分析比对共鉴定出26份鱼胶样品基原鱼种,隶属于5目6科9属12种。系统发育分析表明不同种类的鱼胶处于不同分支中。结论该方法可用于鱼胶基原鱼种的快速分子鉴定,也为鱼胶的真伪鉴定及溯源提供理论依据。

新疆额尔齐斯河北极茴鱼形态性状与纯重的通径分析及基于COI基因序列的系统进化

开展北极茴鱼(Thymallus arcticus)形态性状和纯重间的通径分析,探明北极茴鱼与同属近缘种间的系统进化关系,明确其分类学地位,为制定资源保护管理方案及开展增殖放流工作提供参考资料。对采自新疆额尔齐斯河93尾北极茴鱼样本31个形态性状和纯重进行通径分析,采用PCR技术扩增了线粒体DNA COI基因序列,结合GenBank数据库中下载的茴鱼属鱼类进行系统发育探讨。结果表明,全长(X_(1))、枕骨后末端至腹鳍起点距离(X_(14))、臀鳍起点至背鳍基部末端距离(X_(21))3个指标对鱼体纯重影响最大,可以作为辅助选育的最优表型;COI基因序列分析共得到26种单倍型,单倍型基因多样性(H_(d))为0.984,核苷酸多样性(P_(i))为0.0386,平均核苷酸差异(k)为20.7718,显示出较高的遗传多样性水平;系统发育树显示黑龙江茴鱼、欧洲茴鱼和北美茴鱼各自形成完整的进化枝,北极茴鱼可能存在不同的进化单元,新疆分布的北极茴鱼与短头茴鱼和蒙古茴鱼亲缘关系较近。

基于种特异性COI引物(SS-COI)的桉树枝瘿姬小蜂A、B隐种快速鉴定技术

隐种A和隐种B是桉树枝瘿姬小蜂Leptocybe invasa两种重要的全球入侵隐种,对多国林业生产造成了严重危害。由于桉树枝瘿姬小蜂体型微小,且无法从形态上区分隐种类型,给该害虫的防治造成困难。本研究基于线粒体DNA细胞色素C氧化酶亚基I(mtDNA COI)基因序列的种特异性(species-specific COI,SS-COI)PCR方法,研究桉树枝瘿姬小蜂隐种快速分子检测技术。基于隐种A、B的COI序列分别设计特异性SS-COI引物各1对(AF/AR和BF/BR)。使用这两对引物扩增同一桉树枝瘿姬小蜂样品DNA,即可有效进行隐种鉴定,同时两对引物也能互相验证鉴定结果。引物鉴定灵敏性检测结果显示,AF/AR与BF/BR均具有较高的鉴定灵敏性,其对DNA的有效鉴定浓度阈值分别为11.42 pg/μL和28.32 pg/μL。本研究开发的桉树枝瘿姬小蜂隐种A、B的快速鉴定方法解决了桉树枝瘿姬小蜂入侵地区隐种鉴别的难题,极大缩短鉴定时间、降低鉴定费用,为进一步探究桉树枝瘿姬小蜂隐种A、B的生物学差异以及它们对不同抗性品种桉树的适应能力提供技术参考。

Patenting of hot-rolled high-carbon steel and its applications

The patenting process of three hot-rolled steels with carbon mass contents of 0.70%-0. 90% was studied. The effect of the quenching temperature on the cementite lamellar distance in the steel was evaluated on the basis of microstructural characterization and mechanical property tests. The patenting treatment of high-carbon hot- rolled strip and its application in springs were discussed.

Phase transformation behavior of a hot-rolled,titanium microalloyed steel during heating and continuous cooling

The critical transformation temperatures,A_(c1) and A_(c3),of a hot-rolled low-carbon titanium microalloyed steel were determined as a part of an examination of its phase-transformation behavior. Austenite decomposition during the continuous cooling of the titanium microalloyed steel was studied by heating it to 1 250 ℃,cooling it to 880 ℃,holding for 2 s,and then cooling it to room temperature at different cooling rates. The transformation kinetics( CCT curve) was characterized as well.

Thermomechanical controlled processing of hot-rolled multiphase steel containing Nb

Influence of thermo-mechanical controlled processing(TMCP),including two-stage rolling with laminar cooling,air cooling and ultra-fast cooling,on the microstructure and mechanical properties of three kinds of Nb-microalloeyed steels was investigated by hot-rolling experiment.Effect of chemistry compositions and microstructure on mechanical properties and the relationship between the multiphase microstructure' s formation with TMCP were analyzed.The results showed that the mixed microstructure containing ferrite,bainite,martensite and a small amount of retained austenite can be obtained by thermo-mechanical controlled processing.Size, quantity and distribution of the constituents(ferrite grain,bainite packet and M-A islands) significantly affect the mechanical properties of three kinds of Nb-microalloyed steels.Under the condition of similar TMCP parameters, there is a gradually decreasing tendency in tensile strength from high silicon Nb steel,high silicon Nb-Ti steel to low silicon Nb-Ti steel,and an opposite tendency in total elongation and product of tensile strength and ductility. Total elongation and product of tensile strength and ductility reach the maximum values(41%and 25256 MPa% respectively) for low silicon Nb-Ti steel.

Research on welding technology of hot-rolled extra-high-strength steel developed by Baosteel

In this study, the welding technology of the hot-rolled extra-high-strength steel, BS960QC, has been comprehensively investigated. Analysis has been made on the weldability ,the different welding procedures ,the mechanical properties, and the fatigue properties, and a set of recommendation guidelines have been proposed for evaluating the welded joints of the extra-high-strength steel. The research and results indicate that the hot-rolled extra-high-strength steel, BS960QC,has good weldability and an excellent adaptability to welding procedures. Further,the excellent mechanical properties and fatigue properties of the welded joints ,which can be achieved by using optimized welding procedures, can completely meet the technical requirements of the construction machinery industry.