Microstructure evolution and mechanical properties of 1000 MPa cold rolled dual-phase steel

The microstructure evolution of 1 000 MPa cold rolled dual-phase (DP) steel at the initial heating stages of the continuous annealing process was analyzed. The effects of different overaging temperatures on the microstructures and mechanical properties of 1 000 MPa cold rolled DP steel were investigated using a Gleeble-3500 thermal/mechanical simulator. The experimental results show that ferrite recovery and recrystallization, pearlite dissolution and austenite nucleation and growth take place in the annealing process of ultra-high strength cold rolled DP steel. When being annealed at 800 ℃ for 80 s, the tensile strength and total elongation of DP steel can reach 1 150 MPa and 13%, respectively. The microstructure of DP steel mainly consists of a mixture of ferrite and martensite. The steel exhibits low yield strength and continuous yielding which is commonly attributed to mobile dislocations introduced during cooling process from the intercritical annealing temperature.

Influence of Rolling Temperature in Supercooled Liquid Region on the Surface Morphology of Zr_(52.5)Al_(10)Ni_(10)Cu_(15)Be_(12.5) Bulk Metallic Glass

Surface morphologies of Zr52.5 Al10 Ni10 Cu15 Be12.5 bulk metallic glass after being rolled at both a temperature around T9 and near （ Tx - 50） K were investigated with a scanning electron microscopy. Macroscopic and microscopic observation results show that squamae, cracks, steps and wedges exist on the surface when the samples were rolled at temperatures around Ty. However, a smooth and fiat surface appears when the samples were rolled at temperatures near （ Tx - 50） K. These results indicate that the mode of deformation in the supercooled liquid region is a partially homogeneous flow at a temperature around T9, and a fully homogeneous one at temperatures near （ Tx - 50） K. According to the results, it is more feasible to roll the amorphous alloys at temperatures near （ Tx - 50） K to obtain parts with smooth and fiat surface.

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 microstruc-ture 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 (4 um) and 35%~40% fibrous martensite, presented optimum tensile and impact properties because of enhanced resistance to crack propagation.

Tensile strength prediction of dual-phase Al0.6CoCrFeNi high-entropy alloys

The evolution of the microstructure and tensile properties of dual-phase Al0.6CoCrFeNi high-entropy alloys(HEAs)subjected to cold rolling was investigated.The homogenized Al0.6CoCrFeNi alloys consisted of face-centered-cubic and body-centered-cubic phases,presenting similar mechanical behavior as the as-cast state.The yield and tensile strengths of the alloys could be dramatically enhanced to^1205 MPa and^1318 MPa after 50%rolling reduction,respectively.A power-law relationship was discovered between the strain-hardening exponent and rolling reduction.The tensile strengths of this dual-phase HEA with different cold rolling treatments were predicted,mainly based on the Hollomon relationship,by the strain-hardening exponent,and showed good agreement with the experimental results.

东北漫川漫岗黑土区典型农业小流域切沟沟头形态特征及其影响因素

[目的]研究中国东北漫川漫岗黑土区典型农业小流域切沟沟头形态特征及其影响因素,为控制黑土区沟壑侵蚀提供基础数据和理论支撑。[方法]以黑龙江省海伦市海南乡典型农业小流域切沟沟头为研究对象,野外实地调查沟头形态特征及土壤类型和土体构型,解析沟头形态特征与沟头内因(土壤特性)及外部环境因素的相关性,分析内外因素对沟头形态的影响。[结果](1)海南乡小流域切沟沟头土壤类型为典型黑土、草甸黑土和冲积土,土体构型以腐殖质层(A)+淀积层(B)+母质层(C)型为主,以腐殖质层(A)+母质层(C)及腐殖质层(A)+母质层(C)+埋藏层(Ab)型为辅。(2)相关性分析表明,沟头形态与内外因素呈现复杂的相关性,单一形态不仅受内外因素的影响,同时受自身形态的共同作用影响。(3)冗余分析表明,土体构型、汇水面积、沟头坡度是影响沟头形态的主要因子,且与沟头形态呈正相关关系;沟头植被覆盖度、作物距沟头距离、沟头垄向与沟头立面夹角与沟头形态呈负相关关系。[结论]切沟沟头形态特征复杂,土壤垂向差异性是内因的根本,沟头形态受内外因素共同影响。

热带地区筑坝智能管控一体化技术实践

文章依托迈湾水利枢纽工程,针对热带地区筑坝的特点和难点,进行拌和、运输、碾压、温控等智能实施专题研究,通过对筑坝材料的管理及运输、大坝的碾压质量和温度的控制、试验管理等信息的全过程监控及实时调控,形成热带地区筑坝智能管控一体化技术。整个项目实施成果在极大地降低了人力成本的同时,也保证了大坝建设质量。该技术实践可为同类水利项目提供有效思路。

Wear analysis of a side dam in twin-roll strip casting

Reducing wear on a side dam can prolong the casting operation life of a twin-roll strip casting process,thus reducing production cost and improving casting stability.To lengthen the service life of the side dam,it is necessary to understand the wear performance of the side dam material.To investigate the wear behavior mechanism of the side dam,in this study,the UMT-2 friction and wear tester was used to determine the relationship between the wear rate of the side-dam material and various parameters.Based on the roughness of the contact area between the side dam and the end of the casting rolls as well as on the amount of deformation of the side dam,which was derived using a thermal-deformation simulation model,the reasons for the uneven wear of the side dam were obtained.

某型市域车转向架抗侧滚扭杆结构设计与试验验证

针对某型市域车转向架的输入要求,设计开发了一款抗侧滚扭杆产品,扭杆与扭臂采用过盈配合结构。通过理论计算,得到该过盈配合能够传递的最小力矩为17.76kN·m,防滑安全系数为2.89;通过有限元分析计算,得到该扭杆侧滚刚度为3.2495 MN·m/rad,扭杆最大应力为674.3 MPa,扭臂最大应力为309.5 MPa,最小疲劳强度因子FOS为1.719。样品通过了刚度、静强度和疲劳试验。理论与试验均证明,该抗侧滚扭杆满足功能和强度要求。

X80管线钢边部横裂纹成因分析

利用金相显微镜、扫描电镜并结合轧制工艺,对X80管线钢存在的边部横裂纹缺陷位置的微观组织进行分析。研究发现:在粗轧阶段由于板材边部与轧辊、冷却水和空气进行着强烈的三维热传导和热交换,导致边部温度比中间低,随着温度的降低和变形量的增加,诱导铁素体相变,边部进入两相区,X80管线钢在两相区轧制过程中导致先共析铁素体变形成扁平状,先共析铁素体在轧制过程中产生变形,成流线型组织,而心部仍为奥氏体,此类先共析铁素体从奥氏体相变得到,奥氏体塑性优于先共析铁素体,变形铁素体未来得及发生动态回复,当轧制变形力超过变形极限时导致边部开裂;此外,Nb在奥氏体中固溶度高于铁素体,边部处于两相区时,NbC和TiC钉扎在晶界,抑制了钢的动态再结晶,且存在于晶界的析出物弱化晶界,导致塑性变形能力差,作为应力集中源,均会导致开裂。

考虑双重不确定性的区域综合能源系统多阶段滚动随机规划

在绿色能源转型的背景下,以新型电力系统为核心的区域综合能源系统(RIES)多能耦合程度逐渐加深。在长期的规划运行过程中,除了源荷本身固有的常规预期波动特性外,还容易受到外界扰动的影响,从而产生非预期的不确定性。因此,文中提出了一种考虑预期与非预期双重不确定性的RIES多阶段滚动随机扩展规划。首先,针对RIES长期规划以及常规多能源荷预期不确定性,考虑建设过程中的投资成本、能源站收益、碳税等,基于信息间隙决策理论建立RIES多阶段随机规划模型。然后,考虑规划过程中突发的非预期不确定性,借鉴模型预测控制理论,建立RIES多阶段滚动随机规划。最后,以中国江苏地区的JSYZ-66节点测试系统为例,验证了所提方法在长期规划中面对常规源荷预期不确定性以及规划过程中非预期不确定性的有效性,分析了在风险投机和风险规避策略下规划方向的选择对于规划结果的影响。

弱垂直风切变环境下强下击暴流双偏振雷达特征

基于S波段双偏振多普勒天气雷达和常规观测资料,分析发生于2022年6月26日、6月30日和7月2日弱垂直风切变环境下强下击暴流的双偏振特征,探讨其物理机制。研究表明:3次强下击暴流的对流不稳定能量较强,但垂直风切变较小。6·30风暴和7·2风暴低层较湿,中(上)层略干,6·26风暴除近地层外整层较干。在垂直风切变较弱且0℃层高度较高的环境下,强下击暴流同时伴有高强度分钟降水量(超过3 mm)是其重要特征之一;强下击暴流产生前,风暴强度较强且风暴顶较高(超过10 km),0℃层及以上高度存在超过3.0°·km^(-1)的差分相移率高值区,表明液态粒子或融化的小冰相粒子浓度较高,可视为风暴液态粒子质量团的悬垂,类似于强反射率因子核的悬垂及下降,诱发强下击暴流并伴有短时高强度降水;由于夹卷层平均风速较小,该类强下击暴流动量下传机制较弱,如果空气较湿,强下击暴流的主要机制为重力拖曳及冰相粒子的融化作用,如果空气较干,还应考虑干空气的夹卷蒸发作用。

东北漫川漫岗区极端降水时空变化特征

为探讨东北漫川漫岗区极端降水时空变化特征,基于东北漫川漫岗区1981~2015年79个气象站点逐日降水数据,建立极端降水指标体系,采用气候倾向率法、变差系数C_(V)、M-K突变检验法、R/S分析法、GIS空间分析法综合分析了东北漫川漫岗区极端降水强度、频率、持续性指数的时空变化特征。结果表明,1981~2015年东北漫川漫岗区降水极端性整体呈减弱趋势,R×1day、R×5day、R12D、R50D、CRED分别以-0.5mm/10a、-2.1 mm/10a、-0.2 d/10a、0.02 d/10a、0.03 d/10a的速率减小;强度指数的年代变化呈“升-降-升”状态,频率指数与持续性指数的年代变化皆呈“降-升”状态,2010年代较2000年代上升12.5%~15.0%;频率指数R50D的C_(V)值为0.45,波动剧烈,其他指数的C_(V)值小于0.2,波动幅度较小;R50D与CRED分别在1988、1990年发生突变,在突变点前呈增加趋势,突变点后呈减弱趋势;极端降水指数未来变化趋势与历史变化趋势相反,降水极端性加剧;极端降水呈自东南向西北逐渐减少的分布规律,与1980年代相比,1990年代大部地区极端性有所增加,2000年代极端性减弱,2010年代东北漫川漫岗区南部极端降水强度减轻、频率降低、持续性减弱,北部高海拔地区极端降水强度增强,频率增加,极端降水发生风险较大。该研究可为制定东北漫川漫岗区应对极端降水侵蚀风险的策略提供理论依据。

Effects of Technological Parameters on Microstructures and Properties of Low Cost Hot Rolled Dual-Phase Steel on CSP Line

The effects of technological parameters on microstructures and properties of low cost hot rolled dual-phase steel was researched by design different finish rolling temperature,mid cooling temperature between laminar cooling and UFC (ultra fast cooling) and stable UFC rate on the same gauge strips with the same chemistry composition during the manufacture process.It is the key for controlling coil temperature to control finish rolling temperature and mid cooling temperature between laminar cooling and UFC that based on stable UFC rate precondition.The lower finish rolling temperature,with mid cooling temperature between laminar cooling and UFC,the better to form martensite is.The foundation of developing the similar productions on the similar product line was supplied.It is good to technological advancement of developing high affixation value production as hot rolled DP steel,TRIP steel etc.in CSP line.

考虑供需不确定性的区域综合能源系统时间解耦分层能量管理

进行以电为核心的区域综合能源系统运行优化研究,有利于提高能源利用率及系统运行的经济性、可靠性。针对区域综合能源系统中可再生能源出力与负荷需求的不确定性,提出基于能量枢纽的时间解耦分层能量管理策略。基于可再生能源和负荷预测的日前静态优化,实现了多种能源形式的协调利用。在基于反馈校正的日内滚动优化中引入储能一致性系数,使储能的日内滚动优化功率尽可能遵循日前静态优化结果,提高储能长时间尺度参与系统功率平衡的能力,降低系统供需不确定性的影响,系统抗干扰性增强;同时,根据功率预测误差按储能容量均衡分配备用功率,以提高惯性时间常数较小的电力电子化系统的安全稳定性。算例仿真证明了上述优化模型和策略的有效性。

IF钢铁素体区轧制的变形抗力模型

利用Gleeble热模拟试验机对IF钢铁素体区轧制的变形抗力进行了试验研究。通过实测铁素体区不同变形温度、应变速率、变形程度和变形抗力的关系,建立了变形抗力的数学模型。通过对模型进行回归分析,证明该模型具有良好的曲线拟合特性,可为IF钢铁素体区轧制力能参数计算提供准确的数学模型。

基于LMD-PCA-LSSVM的滚动轴承安全域估计和状态辨识方法

将安全域的思想引入滚动轴承的状态监测中,综合利用局部均值分解(Local Mean Decomposition,LMD)、主成分分析(Principal Component Analysis,PCA)和最小二乘支持向量机(Least Square Support Vector Machine,LSSVM),进行了滚动轴承运行状态的安全域估计以及正常和各种故障状态的辨识。首先,按一定的时间间隔将采集正常及各种故障状态的振动数据进行分段,每段数据进行LMD后获得各乘积函数分量;其次,基于各段数据的乘积函数分量,利用PCA提取出每段数据的T2和SPE统计量控制限值作为滚动轴承的状态特征量;最后,利用二分类的LSSVM进行滚动轴承运行状态的安全域估计,利用多分类LSSVM进行滚动轴承的正常以及滚动体、内圈、外圈故障四种状态的辨识。试验结果显示安全域估计和多种状态辨识的准确率均较高,验证了本文方法的有效性。

东北漫川漫岗区侵蚀沟发育特征研究

东北漫川漫岗区位于黑土区核心位置,侵蚀沟发育严重。利用3S获取侵蚀沟数量、长度等数据,计算降雨侵蚀力、坡度、坡长,分析侵蚀沟发育特征及三因素对侵蚀沟发育影响。结果表明:东北漫川漫岗区75.11%的发展沟处于发育初、中期,潜在发育危险性较大,沟蚀剧烈程度地域性差异显著,研究区南、北部沟壑密度分别为0.3,0.06km/km2;地形、冻融历时、温差等差异造成降雨侵蚀力对北部侵蚀沟发育影响显著,南部相对较弱;研究区坡度与坡长呈正相关关系,北部坡缓造成坡度与沟壑密度呈线性增加关系,南部坡陡造成坡度与沟壑密度呈线性减小关系,北部、南部地形因子与沟壑密度分别呈线性增加、减小关系,随着坡长的增加,沟壑密度先增加后减小,临界坡长为900m。

径轴向环轧机的可轧区

环件轧制过程中存在着运动学、动力学、金属塑性及缺陷等非线性约束。常规工艺制订方法很难同时满足这些非线性约束条件。本文提出了综合可轧区的概念，并对综合可轧区进行求解，最后将各种非线性约束用几条曲线统一起来。据此可方便地确定径、轴向压下量范围。它不仅可以保证轧制过程的顺利进行，还可避免鱼尾等缺陷的产生，对实际生产具有指导作用。

基于连续小波变换的面波衰减方法研究

面波压制是陆上地震资料处理的主要任务之一。根据面波和有效波在小波域能量和分布区域的不同,提出利用连续小波变换自动压制面波的方法。首先利用大尺度的小波系数自动识别面波区,然后计算每道面波的频带范围,最后对面波区小波系数进行滤波处理并估计出有效信号,根据计算的面波频带范围对估计出的有效信号进行高通滤波得到去除面波后的地震记录。实际地震资料的处理结果表明,与常用的高通滤波方法相比,该方法自动化程度高,压制面波的同时可以减少对有效信号的影响。