薄板坯连铸连轧生产65Mn钢的CCT曲线和淬透性

利用Formaster热膨胀仪和金相法,测定了薄板坯连铸连轧工艺(CSP)生产的高碳高强度65Mn钢的CCT曲线,测得临界点为AC1=719℃,AC3=747℃,Ms=267℃,临界冷却速率为35℃/s。使用扫描电镜和硬度仪分析表明,薄板坯连铸连轧工艺生产的65Mn钢的淬火组织细小均匀,硬度高,比传统工艺生产的65Mn钢的淬透性好。     

酒钢CSP热轧薄板生产工艺研究

CSP技术是世界上最早投入工业化生产的薄板坯连铸连轧技术,它是由连铸机生产出高温的无缺陷板坯,无须加热或清理而直接轧制成材。该文介绍了薄板坯连铸连轧技术的现状、酒钢CSP生产线连铸、加热、轧制、精整生产工艺流程和生产工艺的主要特点,并指出酒钢CSP生产工艺存在生产过程组织难度大、加热炉热能利用率低,轧薄能力不足等问题。     

控制轧制和控制冷却对低碳钢板的组织和抗冷脆性的影响

本文研究了控制轧制工艺参数(奥氏体化温度、道次压下率及终轧温度)对低碳钢板轧后铁素体晶粒平均直径和脆性转化温度的影响及其相互关系。试验结果表明:轧制工艺参数中终轧温度起主要作用,决定着轧后铁素体晶粒平均直径、脆性转化温度及-40℃时的冲击韧性;在约800℃终轧,效果最好。轧后快冷时间及冷却速度对低碳钢板的组织和脆性转化温度影响的试验结果表明,延长快冷时间及加快冷却对轧后组织产生复杂影响:使魏氏组织级别增大;使伪共析珠光体量增加;使珠光体退化及细化。这样复杂的组织变化,对脆性转化温度带来复杂的影响。文中提出了低碳钢中珠光体退化的几种机制。     

薄板坯连铸连轧65Mn钢的热轧组织与力学性能

利用光学显微镜,扫描电子显微镜(SEM),透射电子显微镜(TEM)和拉伸试验机,硬度仪分析薄板坯连铸连轧工艺CSP生产的高碳高强度钢65Mn的热轧板微观组织与力学性能。该钢主要由珠光体和少量多边形铁素体组成,珠光体片层间距在0.2~0.5μm之间。该钢的平均屈服强度为489MPa,硬度为HRC22.3,伸长率达到18%;没有明显的C和Mn元素偏析,力学性能分布均匀。通过与传统连铸工艺生产的65Mn钢热轧组织与力学性能对比,CSP工艺生产的65Mn钢的组织更加细小,性能更加优良和均匀。     

连铸连轧薄板边裂原因分析

采用化学成分分析、金相检验、扫描电镜及能谱分析等方法对连铸连轧（CSP）工艺生产的热轧薄板出现边裂的原因进行了分析。结果表明：裂纹以发散的形状由薄板的边缘向板内延伸,薄板坯边缘的裂纹主要起源于层带状组织、混晶和魏氏组织的界面处以及含有大量夹杂（渣）的部位;裂纹产生的主要原因是拉速过快及浇铸时工艺参数控制不当等。     

薄板坯连铸连轧低成本高性能微合金化钢的研发进展

近年,薄板坯连铸连轧这一崭新的钢铁短流程生产线在我国得到迅速发展,目前在生产线数量、产能以及年产量等方面中国都位居世界前列,并在薄板坯连铸连轧的工艺特征和组织性能控制机理研究等方面开展了大量工作.简要说明了薄板坯连铸连轧工艺的冶金材料学特征,综述了近年我国在利用薄板坯连铸连轧工艺进行低成本高性能微合金化钢的研发方面的进展,重点介绍了薄板坯连铸连轧研究开发的微合金化高强和超高强耐候钢、工程机械用低碳贝氏体超高强钢、高强汽车结构用钢、冷冲压用钢和高性能管线钢等微合金化板带产品的成分、组织和性能.     

热轧薄板钢焊接区组织与性能分析

采用包钢CSP（Compact Strip Production）薄板坯连铸连轧工艺生产L245钢为原料进行螺旋焊管焊接生产,针对生产中焊缝裂纹问题对焊缝区的形貌、组织进行了观察,并对焊缝进行拉伸性能和X射线检验。分析表明,母材与热影响区的交界处（即偏向热影响区的“过渡区”）是L245焊管力学性能最脆弱处,珠光体的形貌是影响其拉伸性能的关键因素。     

薄板坯连铸连轧生产石油套管用J55钢板的实践

结合本钢FTSR薄板坯连铸连轧生产线设备和工艺，开发了薄板坯连铸连轧石油套管专用J55钢。分析了薄板坯连铸连轧工艺与材料组织性能的特点，设计了舍金成分、炼钢工艺和轧钢工艺，进行了现场试生产，检验了产品微观组织和性能。在C—Mn基础上加Nb、Ti微合金化，采用LF＋RH的炉外精炼工艺，结合合理的控轧控冷工艺，达到净化钢质、改善夹杂物形态及分布，提高钢材综合力学性能的目的。     

酒钢CSP热轧薄板板形缺陷研究

CSP技术,即紧凑式带钢生产技术。酒钢CSP采用薄板坯连铸连轧,由连铸机生产出高温的无缺陷板坯,无须加热或清理而直接轧制成材。该文介绍了酒钢CSP生产基本状况,根据2018年酒钢CSP生产冷轧基料和外销卷板形异常卷的统计数据,得出酒钢CSP生产板带板形缺陷主要是浪形,该文分析浪形出现的原因,并根据生产和设备的各方面情况,得到降低浪形缺陷出现概率的防范措施。     

CSP流程生产低碳高强度汽车板组织性能的研究

研究了珠钢电炉CSP工艺生产低碳高强度钢板的热轧工艺与组织性能之间的关系,通过光学显微镜和力学性能试验等检测分析技术分析了控制轧制和冷却各阶段工艺参数对成品板显微组织和力学性能的影响.研究表明:降低终轧温度和卷取温度可有效细化晶粒,提高钢板的强度;采用适当的控轧控冷工艺制度,可以获得不同强度级别强韧性能良好的热轧低碳高强度汽车用钢板.     

Achievements of New Generation Steel Project in China

Major achievements of the national project, Fundamental Research on New Generation of Iron and Steel Materials in China (NG Steel), are reviewed in the paper. Ultrafine grained steel technology, based on deformation induced ferrite transformation (DIFT)and successive microstructure changes, is illustrated for grain refinement in both plain low carbon steel and microalloyed steel. Delayed fracture resistance of alloy structure steel can be improved through prior austenite grain refinement. It is shown by results that nano scale precipitates play an important role to grain refinement in thin slab casting and rolling (TSCR)process. Progresses on super cleanliness, high homogeneity, welding and metallurgical process simulation are also briefly introduced.     

Achievements of New Generation Steel Project in China

Major achievements of the national project, Fundamental Research on New Generation of Iron and Steel Materials in China (NG Steel). are reviewed in the paper. Uhrafine grained steel technology, based on deformarion induced ferrite trartsformation (DIFT)and successivechanges, is illustrated tor grain refinement in both plain low carbon steel and mieroalloyed steel. Delayed fracture resistance of alloy structure steel can be improved through prior austenite grain refinement. It is shown by results that nano scale precipitates play an important role to grain refinement in thin slab casting and rolling (TSCR)process. Progresses on super cleanliness, high homogeneity, welding and metallurgical process simulation are also briefly introduced.     

取向硅钢制备工艺及其发展趋势

取向硅钢作为一种重要的铁芯材料,在电力行业中有着广泛的应用.基于生产工艺及技术特点,取向硅钢的制备工艺可以分为传统厚板坯工艺、薄板坯连铸连轧工艺及双辊薄带连铸工艺.传统的厚板坯工艺是工业生产取向硅钢的主要方法,其按加热温度又可分为板坯高温加热、板坯中温加热以及板坯低温加热工艺,其中板坯低温加热工艺具有加热温度低、能耗少...     

A Discussion on Evolution of Microstructures and Influence Factors during Continuous Rolling of Compact Strip Production

The evolution of microstructures and influence factors of ultrathin hot strips of low carbon steel produced by compactstrip production (CSP) techniques were investigated. The steel blocking samples of CSP six-passes were obtained,and microstructures at the different positions of workpiece for each pass were studied. At the same time, anexplicit finite element technique was used to reveal the continuous rolling process. By combining experiment resultswith simulation analysis, the effects of plastic strain, temperature, precipitation and interval time on evolution andrefinement of crystal grains have been investigated. The results are useful for the development of high strength hotstrips.     

中国钢铁工业的现状和发展

钢铁材料良好的综合性能和易于循环利用等特点,至今仍是人类社会发展所需的不可替代的材料。在过去的20年里,中国的钢铁工业取得了巨大的进步,粗钢年产量已超过1×108t,工艺流程和技术不断得到革新和发展,钢铁品种多样化,满足了国民经济不断发展的需要;薄板坯连铸、低温轧制等高新技术的应用使中国的钢铁工业更具有竞争力和吸引力;致力发展与环境友好、省能的新一代钢铁工业得到了人们广泛的关注;电场、磁场、微波场及超声波等多种物理场将大大强化化学反应和优化凝固过程,它们的运用将会对未来的钢铁工业带来革命性的变化。     

D6A钢在轧制过程中的强韧化机理EI北大核心CSCD

通过轧制-热处理工艺能够使D6A钢的强度显著提高。为了探究其强韧化机理,本实验采用热轧及两相区温轧退火工艺,获得微米级D6A合金钢样品,微观组织为铁素体基体及粒状渗碳体。通过室温拉伸实验、SEM、X射线衍射、EBSD等手段对实验钢的显微组织和力学性能进行表征,结果表明:随着变形量的增加,晶粒尺寸由4.5μm细化为1.5μm,渗碳体的含量逐渐增加,小角度晶界的比例升高,屈服强度和抗拉强度不断增加,伸长率略有降低,说明轧制过程使亚晶粒的尺寸不断降低,晶界面积增加,位错滑移受到的阻力增大。同时,本研究对不同轧制变形量实验钢的位错密度进行计算,当轧制变形量为88%时,位错密度最高,此时加工硬化的程度最高。随着变形量的增加,第二相强化和晶粒细化引起的强度增量呈不断上升的趋势,位错强化引起的强度增量先升高后降低,D6A钢的主要强化方式为第二相强化、细晶强化及位错强化。     

Effect of Strain Rate on the Ferrite Grain Refinement in a Low Carbon Nb-Ti Microalloyed Steel during Low Temperature Deformation

1. IntroductionThe thermomechanical controlled processing(TMCP) of microalloyed steels has been employed fosome times in the production of plates and sheet material to optimize mechanical properties. The centrafeature of thermomechanically processed steel is the ul-trafine grain size in the final product. Therefore, theferrite grain refinement of structural steels has attractedconsiderable interest from engineering scientists due toits unique role of increasing both strength and toughnessDem…     

The influence of cryogenic rolling on a transformation-induced plasticity steel

ABSTRACT

Here, a novel cryogenic rolling plus intercritical annealing process was applied to a transformation-induced plasticity (TRIP) steel with a low chemical composition of carbon and manganese. Compared with traditional cold rolling, obvious grain refinement was observed, due to a high amount of dislocations retained. In addition, austenite volume fraction was increased, because of a unique nucleation mechanism. Subjected to cryogenic rolling, strength and ductility were increased, due to the enhanced austenite stability, which provided continuous and active TRIP effect. Consequently, tensile strength was increased to 1030?MPa, and elongation was increased to 38.2%. Thus, a great mechanical combination was obtained in a steel with a relatively low chemical composition with carbon and manganese, only by cryogenic rolling process.     

Microstructure evolution of medium carbon steel during manufacture process for non-quenched and tempered oil well tubes

The microstructure evolution of medium carbon microalloyed steel during the manufacture sub-processes of N80 grade hot rolling seamless oil well tubes was investigated by compression simulation on Gleblee 1500 thermal simulator and industrial experiments of seamless tubes production. The results show that the tested steel has good anti-coarsening ability at equalization sub-procedure. The quantitative analysis of austenite grain size has illustrated that the average austenite grain size in the steel would almost always continuously increase in the tube manufacture process till just before the stretch-reduction-diameter deformation. The most effective microstructure refinement in industrial experiment did not occur in austenite state, but mainly in austenite decomposition following the stretch-reduction-diameter process. The intra-granular ferrite formation should be very useful for effective refinement of the whole microstructure. The variation tendencies of austenite grain size in simulated and industrial experiments are nearly the same, while the optical microstructures and precipitation characterization are quite different.     

Processing of steel for ultrafine ferrite grain structures

Abstract

The attainment of ultrafine ferrite grain structures in low carbon, low alloy steels is of interest because of the improvement in yield strength and Charpy impact transition temperature predicted by extrapolation of known data to very fine grain sizes. This paper presents a summary of research aimed at producing ultrafine ferrite in a niobium microalloyed, low carbon steel by three processing routes. Transformational grain refinement (TGR), in which extrafine austenite is hot rolled and cooled rapidly, has been shown to be capable of producing grain sizes of <1 µm in a surface layer, and 1.5 µm in the centre of 3 mm thick plate. Dynamic recrystallisation of ferrite during multipass warm rolling was shown to be neither complete nor uniform within the cross-section of the plate. Nevertheless, a partly recrystallised, partly recovered grain structure with an average grain size of 1.5 µm was obtained in the centre of 3 mm thick plate. Cold rolling and recrystallisation of ferrite that had been previously refined by TGR to an intermediate grain size was shown to produce an ultrafine grain microstructure (<1 µm grain size) throughout the section of 1 mm thick strip. The hardness of ultrafine ferrite was shown to obey a linear relationship with the inverse square root of grain size, but with a lower slope than expected from the Petch relationship for yield strength.