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.     

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。     

CSP生产低碳钢的组织演变和析出物研究

为了阐明EAF-LF-CSP工艺生产的低碳钢组织细化机理,在薄板坯和不同道次变形后的同一轧件上取样,利用金相、SEM、TEM、XEDS等技术研究了连轧过程中显微组织演变和钢中第二相析出物.结果表明:与普通连铸板坯相比薄板坯的凝固组织更加细小;随轧制道次增加,薄板坯表面和心部的组织差异逐渐减小,轧后室温组织细化;CSP生产的低碳钢中存在大量纳米尺寸的氧化物和硫化物,起到细化晶粒的作用.CSP生产中采用快速冷却和凝固工艺、单道次大压下连轧工艺和层流冷却工艺,是成品组织细化的主要原因.     

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。     

薄板坯连铸连轧流程生产高磁感取向硅钢的研究现状与技术分析

概述了高磁感取向硅钢生产工艺的研究现状及发展趋势。介绍了国内外薄板坯连铸连轧流程生产高磁感取向硅钢的研究现状。从流程工序特点、热履历、组织与抑制剂控制方面进行对比,分析了薄板坯连铸连轧流程相对传统板坯流程生产高磁感取向硅钢的技术优势,在此基础上提出了利用该流程生产高磁感取向硅钢需要解决的主要技术难点。     

取向硅钢生产工艺研究进展

结合取向硅钢的传统生产工艺,介绍其生产工艺研究的最新进展,重点介绍了薄板坯连铸连轧生产取向硅钢、异步轧制生产取向硅钢、双取向硅钢生产工艺、磁场退火生产取向硅钢和无抑制剂生产取向硅钢5种取向硅钢生产新工艺。这些新工艺均可在一定程度上提高取向硅钢的性能,有的已进入工业化实践阶段,有的已在实验室取得长足进步。     

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。     

本钢薄板坯连铸连轧生产线节能功能开发

介绍了本钢薄板坯连铸连轧生产线轧机与卷取机部分节能功能的开发原理。在薄板坯连铸连轧生产线的生产中,由于产品低等因素,致使吨钢电耗处在一个较高的水平,此功能主要利用轧制过程中的待机时间,通过对精轧机的速度控制与卷取机起停控制来降低电耗。     

空调管用连铸连轧3003铝合金圆铝杆工艺研究

对3003铝合金圆铝杆生产工艺进行了系统研究,分析了化学成分、熔体净化、连铸连轧工艺和均质退火工艺对3003铝合金圃铝杆组织和性能的影响。     

Modeling of Microstructure Evolution and Mechanical Properties of Steel Plates Produced by Thermo-Mechanical Control Process and Its On-line Application

An integrated metallurgical model was developed to predict microstructure evolution and mechanical properties of low-carbon steel plates produced by TMCP. The metallurgical phenomena occurring during TMCP and mechanical properties were predicted for different process parameters. In the later passes full recrystallization becomes difficult to occur and higher residual strain remains in austenite after rolling. For the reasonable temperature and cooling schedule, yield strength of 30 mm plain carbon steel plate can reach 310 MPa. The first on-line application of prediction and control of microstructure and properties (PCMP) in the medium plate production was achieved. The predictions of the system are in good agreement with measurements.     

轧后冷却速率对14CrMoR钢板热处理后显微组织和力学性能的影响

首先对14CrMoR钢进行了轧制后不同冷却速率的冷却,然后进行了相同工艺的正火+回火热处理,研究了轧后冷却速率对14CrMoR钢板热处理后显微组织和力学性能的影响。结果表明:轧后冷却速率越小,钢板热处理后的各类显微组织越细小,珠光体和回火贝氏体组织的分布越均匀,综合力学性能也越好。     

Predicting microstructural evolution and yield strength of microalloyed hot rolled steel plate

Abstract

A mathematical model has been developed to optimise process parameters for production of API grade steel plates by thermomechanical controlled processing at a plate mill in Bhilai Steel Plant, India. The model comprises the prediction of the microstructural evolution during hot rolling, the subsequent phase transformation, and, finally, the mechanical properties of microalloyed steels. Effects of chemistry and mill parameters on recrystallisation, grain growth, and precipitation kinetics were taken into consideration to describe the metallurgical processes. . The model has been validated through laboratory experiments as well as full-scale rolling at the plate mill.     

极地破冰船用大线能量型高强度船板的开发

采用微合金化的设计思路,钢板成分在低C、低碳当量的基础上添加少量的Nb、Ti等微合金化元素,同时在冶炼过程中采用氧化物冶金技术,在TMCP轧制过程中采用针对低碳当量的超快冷技术,最终在成品钢板中得到低碳贝氏体+铁索体混合组织,钢板强韧性匹配良好,-60℃冲击功达到200 J以上.采用100～250 kJ/cm的线能量进...     

Microstructure—Properties Correlation of Dual Phase Steels Produced by Controlled Rolling Process

The purpose of this research is to quantify the effects of compositional and processing parameters on the microstructure and properties of dual phase steel produced directly by hot rolling and rapid cooling.Steels with the base composition of 0.1%C,1.4%Si,and 1.0%Mn with additions of 0.5%Cr to influence hardenability,0.04%Nb to retard recrystallization in the latter stages of rolling,or 0.02% Ti to inhibit grain growth during and after reheating were investigated.Investigation was made to predict microstructure evolution and to correlate microstructure with processing parameters.The effects of the important microstructure parameters such as ferrite grain size,martensite volume fraction (VM) and morphology (polygonal or fibrous) on the tensile and impact properties are discussed.Multiple linear regression analysis of the ultimate tensile strength has shown that,increasing VM and martensite microhardness and grain refinement of ferrite are the major contributions to increase the strength of the steel.It was found that the dual-phase steel produced by controlled rolling process,with a microstructure which consisted of fine grained ferrite(4μm) and 35%-40% fibrous martensite,presented optimum tensile and impact properties because of enhanced resistance to crack propagation.     

不锈钢/高硼不锈钢层状复合材料组织变化

为了解决高硼不锈钢材料变形难度大、易开裂、塑性低等问题,采用复合浇铸-热轧变形工艺,制备了以难变形金属高硼不锈钢为中间层的层状复合板,研究了复合材料在铸造、热轧和固溶处理各阶段的组织特点及芯层中硼化物的相组成规律.结果表明:含硼质量分数2%～2.5%的复合板芯层的铸态组织主要以共晶组织形式凝固,含硼较高的芯层铸态组织除以共晶组织形式凝固外,还形成大块的含有Cr2B和Fe2B的过共晶硼化物相;热变形使共晶硼化物发生破碎、细化,但过共晶硼化物的体积形状变化不大;固溶处理使覆层中细小的二次析出物明显减少,这有利于复合板的力学性能,但芯层中硼化物的形貌、数量及尺寸变化不大.     

Some new results in thermomechanical processing of microalloyed steels

In recent times, efforts have been directed towards a better understanding of the mechanisms associated with deformation and restoration of austenite during continuous multipass hot rolling of microalloyed steels. The correspondence between the condition of austenite before transformation and the resultant microstructure upon cooling holds the key to the attainment of interesting properties. In the present paper, some results obtained on the deformation of austenite in a microalloyed steel, using a hot compression machine, are presented. Here, the idea was to simulate actual plate rolling or hot strip rolling conditions and study the evolution of microstructure at different stages of the hot deformation process i.e. after precise reductions at given strain rate and temperature of deformation. The paper further discusses recent results obtained by us on the influence of hot deformation parameters (strain, finish rolling temperature, temperature of deformation) and cooling rates (air cooling, spray water cooling) on the microstructure of microalloyed steel. The precise conditions leading to the evolution of acicular ferrite and bainitic microstructures have been identified. New information on the influence of short tempering treatments (15 min at 550, 600 and 650°C) on the microstructure and properties of a microalloyed steel are also outlined.     

Q460C钢组织特性对表面裂纹成因的影响分析

通过光学显微组织观察,测定显微组织硬度和能谱分析等方法对Q460C中厚板表面裂纹成因进行了分析研究,分析了热送热装工艺对裂纹形成的影响,分析了轧制过程中裂纹的形成机理.利用热膨胀法结合金相法在Gleeble-1500热模拟实验机上测定了实验钢连续冷却转变曲线,分析了材料组织转变与裂纹形成规律的联系.分析结果表明：热送热...     

热镀锌钢板用冷轧板退火工艺的确定

采用盐浴退火方法分别对牌号为SSGrade40,SSGrade33和SSGrade50的热镀锌钢板的冷轧硬卷进行了不同工艺的退火处理,研究了退火工艺对三种热镀锌钢板用冷轧板显微组织和力学性能的影响,以确定三种冷轧板的再结晶温度及最佳退火温度范围。结果表明：SSGrade40冷轧板的再结晶温度在720℃左右,退火温度在720℃较佳;SSGrade33冷轧板的再结晶温度在680℃左右,考虑到力学性能的稳定性,退火温度选择在720℃左右较佳;SSGrade50冷轧板的再结晶温度在700℃以上,为了保证其强度富余量和性能稳定性,退火温度选择在780℃左右较佳。     

镍-不锈钢复合板轧制过程中界面的结合机制

采用轧制终止取样法对镍-不锈钢热轧复合板轧制过程中的界面成分、界面组织以及界面处的氧化物进行了表征,研究了轧制过程中界面的结合机制并根据热力学原理解释了高温下选择性内氧化的机理。将复合板坯加热至1200℃,保温120 min后进行轧制,分别在轧制3、5、7道次后中断轧制快速水冷,随后进行取样观察。结果表明,轧制3道次时终轧温度为1000℃左右,金属之间有近距离结合,微观组织有轻微的畸变,界面两侧的板材均为等轴晶粒,元素的扩散不甚明显;轧制至5道次时终轧温度为940℃左右,316H的晶粒被拉长而发生晶格畸变,界面附近出现明显的扩散行为;轧制到7道次时终轧温度为880℃,316H层出现大量拉长的畸变晶粒,界面处主要是轧碎的细晶组织,但Ni层的晶粒粗大,界面附近Ni、Fe和Cr元素充分扩散,微弱扩散的Mo元素在316H界面富集。镍-不锈钢复合板在轧制过程中界面的演化遵循三阶段理论和N.Bay理论,3道次到5道次间处于物理接触阶段、物理化学阶段,轧制7道次时物理化学阶段结束并开始扩散,即开始进入“体”相互阶段,主要元素在此阶段完成相互扩散。在高温低氧环境的轧制条件下,界面处生成Mn的氧化物,该氧化物因轧制而破碎并向基材挤压最终在界面附近成链状分布。