Texture evolution of commercial pure Ti during cold rolling and recrystallization annealing

X-ray diffraction (XRD) was employed to analyze the texture evolution of commercial pure (CP) Ti during cold rolling and re-crystallization annealing. The texture components were measured by electron backscattered diffraction (EBSD) after recrystallization an-nealing. The CP Ti tends to form a texture with the basal pole tilted 30°-40° away from the normal direction toward the transverse direction. The texture of the initial hot-rolled plate can be classified into three kinds, i.e., the pyramid texture and , the basal plane texture , and the stronger prism texture . After cold rolling and annealing (700°C, 60 min), the main texture components are the cold-rolled texture and the recrystallized texture . The texture is in-herited from the texture of the initial hot-rolled plate with the decrease of orientation density gradually. The volume contents of the cold-rolled texture and the recrystallized texture are calculated by EBSD. After recrystallization annealing, the specimen is rich in the recrystallized texture and inherits some of texture components from the cold-rolled texture. When the annealing time is prolonged, the anisotropic value decreases.     

IF钢生产过程中的织构演变

对IF钢生产过程中热轧、冷轧及退火试样的织构演变进行研究。分别借助EBSD和XRD测定和计算了热轧、退火及冷轧试样的取向分布函数及相关织构组分的体积分数。结果发现,热轧板在变形过程中发生了动态再结晶,晶粒为细小的等轴晶,为后续组织发展提供了基础;热轧后试样中的织构很弱,不会影响冷轧织构组分及含量。冷轧过程是织构形成的主要过程,试样中含有4种主要的织构组分：{001}〈110〉、{111}〈110〉、{111}〈112〉和{112}〈110〉。退火过程中发生再结晶,4种冷轧织构组分在退火过程中均分别转变为{111}面织构。     

Microstructures and properties of 550 MPa grade high strength thin-walled H-beam steel

The microstructures and mechanical properties of 550 MPa grade lightweight high strength thin-walled H-beam steel were experimentally studied. The experimental results show that the microstructure of the air-cooled H-beam steel sample is consisted of ferrite, pearlite and a small amount of granular bainites as well as fine and dispersive V（C,N） precipitates. The microstructure of the water-cooled steel sample is consisted of ferrite and bainite as well as a small amount of fine pearlites. The microstructure of the water-cooled sample is finer than that of the air-cooled sample with the average intercept size of the surface grains reaching to 3.5 gna. The finish rolling temperature of the thin-walled high strength H-beam steel is in the range of 750 ~C-850 ~C. The lower the finish rolling temperature and the faster the cooling rate, the finer the ferrite grains, the volume fraction of bainite is increased through water cooling process. Grain refinement strengthening and precipitation strengthening are used as major strengthening means to develop 550 MPa grade lightweight high strength thin- walled H-beam steel. Vanadium partially soluted in the matrix and contributes to the solution strengthening. The 550 MPa grade high-strength thin-walled H-beam steel could be developed by direct air cooling after hot rolling to fully meet the requirements of the target properties.     

变形温度对细晶高强IF钢应力-应变曲线及显微组织的影响

以细晶高强IF钢为研究对象,在东北大学轧制技术及连轧自动化国家重点实验室MMS-300热力模拟实验机上,测定了在变形速率为10s^-1,真应变为0．5,变形温度分别为750、800、850、900、950、1000℃时的应力应变曲线。通过实验发现,钢的应力应变曲线为动．态回复型,不随温度而变化;流变应力随着变形温度的增加而下降;通过显微组织观察发现,随变形温度的降低,晶粒变细。     

Ti微合金化450-550MPa级耐候钢组织性能研究

设计了屈服强度达450-550MPa级高强耐候钢化学成分,在实验室进行冶炼和热轧试验,测试和观察了试验钢的力学性能和显微组织,分析了Ti含量对Ti微合金化耐候钢性能的影响。结果表明,试验钢的金相组织主要为在多边形铁素体基体上分布少量的珠光体;Ti微合金化耐候钢具有足够的强度和塑性,随着W（Ti）从0．025％增加到0．07％,试验钢的屈服强度从360MPa增加到550MPa;采用传统控轧控冷工艺可生产出屈服强度达450～550MPa级高强耐候钢。     

Experimental study on 830 MPa grade pipeline steel containing chromium

The diversity of microstructure and properties of 830 Mpa grade pipeline steel containing chromium was investigated by optical microscope and transmission electron microscopy. The main microstructures were multiple configurations, containing lath bainite and granule bainite. Mechanical properties test results showed that the yield strength and tensile strength improved with in-creasing chromium content. The toughness and elongation decreased at the same time, so temper process was introduced. Appling proper temper parameters, the values of toughness and elongation were improved dramatically, and the strength decreased slightly.     

电炉法生产IF钢的工艺研究

提出了用电炉法生产IF钢的合理工艺配置,阐明了通过采取相应的技术措施如选择合适的炉料配比(增加铁水、DRI或生铁的使用量)、正确的生产操作(如电炉内吹氧喷碳造泡沫渣、钢包内脱氧,注意钢水在连铸过程中的保护浇注等)并配备合适的钢水二次精炼设备如LF+VTD-OB后,可以生产部分IF钢(CQ,DQ和DDQ级)产品.     

Modeling texture development during cold rolling of IF steel by crystal plasticity finite element method

With the consideration of slip deformation mechanism and various slip systems of body centered cubic (BCC) metals,Taylor-type and finite element polycrystai models were embedded into the commercial finite element code ABAQUS to realize crystal plasticity finte element modeling,based on the rate dependent crystal constitutive equations.Initial orientations measured by electron backscatter diffraction (EBSD) were directly input into the crystal plasticity finite element model to simulate the development of rolling texture of interstitial-flee steel (IF steel) at various reductions.The modeled results show a good agreement with the experimental results.With increasing reduction,the predicted and experimental rolling textures tend to sharper,and the results simulated by the Taylor-type model are stronger than those simulated by finite element model.Conclusions are obtained that rolling textures calculated with 48 {110}<111>+{ 112}<111>+{123}<111> slip systems are more approximate to EBSD results.     

一种冷轧高强钢板的纳米析出物

在研究纳米析出强化热轧钢板的基础上,对该钢板进行了冷轧退火试验研究。采用透射电镜（TEM）和能谱分析等方法分析了析出物的分布和形貌,测定了两种纳米析出物的成分。结果表明,试验钢经退火处理后存在着两种形状的析出物,矩形析出物尺寸为30-50nm,主要由TiN组成;圆形析出物为5～10nm,主要由TiC组成。这些析出物的出现将直接影响实验钢的性能及应用。     

高强度钢54SCV6超高周疲劳研究

介绍用２０ＫＨｚ超声波振动疲劳试验机对一组高强度钢５４２ＳＣＶ６的２９个试件的超高周疲劳强度研究结果,研究发现,中材料的高周直到超高周区间疲劳强度随材料寿命的加大呈明显减小,即Ｓ－Ｎ曲线呈明显下降。这一结果与传统的假说认为该区间的疲劳强度为水平渐近线或为一定值完全不同。     

Microstructure homogenization control of Nb-bearing X65 pipeline steel by the CSP process

In order to get the controlled methods of microstructure homogenization and high strengthening-toughening combination by compact strip production (CSP) rolling,the dynamic recrystallization characteristics of each pass were obtained during CSP rolling using a Gleeble-1500 thermal mechanical simulator.Then,the CSP process was simulated by laboratory rolling experiment.Through thermal mechanical simulation experiment and laboratory rolling experiment,a design idea of Nb-bearing pipeline steel by CSP can be ob...     

常温与高温下高强钢T型连接受拉性能试验

为研究高温下高强钢T型连接的受拉性能,对11个常温下和17个高温下的T型连接试件进行拉伸试验,其中包括300、400、500、600℃等多种高温环境下Q355、Q460、Q690、S690、S960等不同强度钢材的T型连接,通过试验得到各T型连接的初始拉伸刚度、抗拉承载力、破坏模式等。将试验结果与欧洲规范和中国规程的计算结果进行对比,以期校验规范对于高强钢T型连接的适用性,并分析翼缘强度、翼缘厚度、螺栓强度、螺栓直径、螺栓位置以及高温温度等多种因素对T型连接受拉性能的影响。常温与高温下的试验结果表明：欧洲规范和中国规程对高温下高强钢T型连接初始拉伸刚度的估算偏于危险,而对抗拉承载力而言偏于保守;与普通钢T型连接相比,薄翼缘高强钢T型连接能在保持承载能力相当的情况下,具有更好的变形能力;当螺栓离腹板距离和翼缘距离的比值小于1时,增大螺栓离腹板的距离会显著降低T型连接的初始拉伸刚度和抗拉承载力;螺栓直径的增加将增大T型连接初始拉伸刚度值,但螺栓强度对初始拉伸刚度影响不大。本文研究成果可为高强钢端板连接节点及其等效T型连接的抗火设计提供试验依据,为相关规范修订提供参考。     

Mechanical performance and texture characteristic of an IF steel containing Nb and Ti by double cold rolling

Single cold rolling and double cold rolling were applied to hot rolled strips with different reduction ratios. The evolutions of {100},{111} and Goss face texture during double rolling were investigated by comparing the orientation distribution function(ODF) of the double rolled sample with that of the single rolled one. The double cold rolling texture is characterized by a higher γ-texture and a lower α-texture,and the {111}<112> component is improved remarkably. Based on the TEM observation and mechanical...     

约束高强度Q460钢梁的抗火性能

为了研究约束高强度Q460钢梁的抗火性能,在已有约束钢梁分析理论的基础上,引入残余应力,提出了约束钢梁的抗火性能分析方法,并采用普通强度约束钢梁试验数据对分析方法进行了验证。考虑高强度Q460钢材高温下力学性能参数,利用所提出的方法分析了约束高强度Q460钢梁的抗火性能,并与普通强度Q345钢梁进行了对比。对影响约束高强度Q460钢梁的抗火性能参数进行了分析,包括荷载比、残余应力、轴向约束刚度、转动约束刚度和受火方式等。研究表明:所提出的分析方法准确可靠,高强度Q460钢梁抗火性能与普通强度钢梁具有较大的区别,高强度Q460约束钢梁的抗火性能明显优于普通强度约束钢梁。荷载比、轴向约束刚度、转动约束刚度、受火方式对高强度Q460约束钢梁有较大影响。     

高强钢筋混凝土桥墩抗震性能试验研究

试验对配有HRB500高强钢筋混凝土桥墩试件进行低周往复加载试验,比较不同钢筋强度、箍筋间距和轴压比对桥墩试件的破坏特征、承载能力、位移、滞回特性、骨架曲线、刚度退化和耗能能力等抗震性能指标的影响。研究表明:钢筋强度、轴压比和箍筋间距对配有HRB500高强钢筋混凝土桥墩的抗震性能影响效果显著。增大钢筋强度、减小轴压比和减小箍筋间距都能够提高高强钢筋混凝土桥墩试件的变形能力,在提高桥墩试件滞回性能的同时,减缓试件的刚度退化。增大钢筋强度、增大轴压比和减小箍筋间距可以增强桥墩试件的极限承载力。     

汽车超高强钢防撞梁热成形试验

以汽车用超高强度钢22MnB5为研究对象,采用直接热成形工艺和间接热成形工艺进行汽车防撞梁成形试验。采用金相显微镜、显微硬度仪和万能拉伸试验机等分析测试手段对成形件的组织、力学性能进行了分析。探讨了直接、间接热成形工艺对成形组织及力学性能的影响。结果表明,成形件的微观组织为理想的板条状马氏体,抗拉强度达到1500MPa以上,硬度在450HV以上,完全满足生产要求,实际生产中可以根据情况选择合适的成形工艺。     

Microstructure and texture evolution in commercial-purity Zr 702 during cold rolling and annealing

Microstructure and texture evolution in commercial-purity Zr 702 during cold rolling and annealing was investigated by optical microscopy, transmission electron microscopy, and X-ray diffraction. The results showed that crystallographic slip was the predominant deformation mechanism in the early stage of deformation. Deformation twins started to form when the rolling reduction was larger than 38.9%; both the dislocation density and the number of twins increased with increasing rolling reduction. The initial texture of the Zr 702 plate consisted of the basal fiber component. During cold rolling the strength of the basal fiber first decreased and then increased with increasing rolling reduction. The cold-rolled sheets were fully recrystallized after being annealed at 550℃. The recrystallization temperature and the size of recrystallized grains decreased with increasing rolling reduction. A larger rolling reduction resulted in a higher grain growth rate when the annealing temperature increased from 550℃ to 700℃. The recrystallization texture was characterized by a major basal fiber and a minor {0113}〈2110〉 component. The strength of the recrystallization texture increased with increasing rolling reduction.     

钢纤维高强混凝土及其在框架节点中的应用分析

介绍了钢纤维高强混凝土的特点以及在框架节点中的应用,制作了1个高强混凝土和1个钢纤维高强混凝土框架中节点试件,研究其在低周反复荷载作用下的变形、强度和刚度退化、延性和耗能能力。结果表明：与普通混凝土节点相比,钢纤维混凝土节点的开裂荷载较高、承载能力和变形能力良好、滞回曲线更为饱满、延性和耗能指标也较高,有利于结构抗震,对于解决节点区箍筋过密有显著作用,指出了钢纤维高强混凝土具有广阔的应用前景。     

Research on microstructural evolution and dynamic recrystallization behavior of JB800 bainitic steel by FEM

Single pass compression tests were conducted on Gleeble1500 thermal simulator. The effect of different deformation parameters on the grain size of dynamically recrystallized austenite was analyzed. A mathematical model of dynamic recrystallization and a material database of JB800 steel, whose tensile strength is above 800 Mpa, were set up. A subprogram was compiled using Fortran language and called by Marc finite element software. A thermal coupled elastoplastic finite element model was established to simulate the compression process. The grain size of recrystallized austenite obtained by different recrystailization models was simulated. The results show that the optimized dynamic recrystallization model of JBS00 bainitic steel has a higher precision and yields good agreement with metallographic observations.     

Research on microstructural evolution and dynamic recrystailization behavior of JB800 bainitic steel by FEM

Single pass compression tests were conducted on Gleeblel500 thermal simulator.The effect of different deformation pa- rameters on the grain size of dynamically re,crystallized anstenite was analyzed.A mathematical model of dynamic re,crystallization and a material database of JB800 steel,whose tensile strength is above 800 MPa,were set up.A subprogram was compiled using Fortran language and called by Marc finite element software.A thermal coupled elastoplastic finite element model was established to simulate the compression process.The grain size of recrystallized austenite obtained by different recrystallization models was simu- lated.The results show that the optimized dynamic recrystallization model of JB800 bainitic steel has a higher precision and yields good agreement with metaliographic observations.