Head Curvature of Pure Titanium Sheet Influenced by Process Parameters and Controlling in Hot Rolling Process

We investigated the influences of process parameters on the head curvature of pure titanium sheet in hot rolling process and proposed the controlling means. First, the thermal simulation experiments for pure titanium TA1 were carried out to investigate the hot deformation behaviors of pure titanium in the temperature range of 700-800 ℃ with strain rate range of 1-20 S-1, and the processing map was established to determine optimized deformation parameters. Then, the finite element model has been constructed and used to analyze the effect of process parameters on the direction and severity of head curvature of pure titanium sheet. The process parameters considered in the present study include workpiece temperature, work roll diameter, pass reduction, oxide scale thickness of workpiece surface, and interface friction coefficient. The simulation results show that the workpiece temperature and the interface friction coefficient are the two main factors. The proposed controlling means was carried out on a hot rolling production line and solved the head curvature problem effectively. The rolling practices indicate that the rolling yield is improved greatly.

Mathematical model for cooling process and its self-learning applied in hot rolling mill

Control precision of coiling temperature is one of the key factors affecting the profile shape and surface quality during the cooling process of hot rolled steel strip.For this reason,the core of temperature control precision is to establish an effective cooling mathematical model with self-learning function.Starting from this point,a cooling mathematical model with nonlinear structural characteristics is established in this paper for the cooling process of hot rolled steel strip.By the analysis of self-learning ability,key parameters of the mathematical model could be constantly corrected so as to improve temperature control precision and adaptive capability of the model.The site actual application results proved the stable performance and high control precision of the proposed mathematical model,which would lay a solid foundation to improve the steel product qualities.

Effect of gradient temperature rolling process on promoting crack healing in Q500 heavy plates

To ensure the quality of heavy plate products as determined by ultrasonic inspection, it is necessary to effectively control defects such as cracks and shrinkage cavities in heavy plates. Generally, some defects such as large size cracks exist due to insufficient deformation in the center of traditionally rolled plates. Compared with the traditional rolling process, gradient temperature rolling(GTR) process can effectively increase deformation inside heavy plates. In this study, the effect of GTR on crack healing was analyzed through a comparison experiment with the uniform temperature rolling(UTR). The results show that the GTR process could increase the plastic strain inside the heavy plate and effectively promote the healing process of the preset cracks. The degrees of crack healing at the center and quarter thickness position of the steel plate via GTR were greater than twice those of the plate via UTR. The GTR process can significantly reduce the internal defects of heavy plates and improve the defect detection level of heavy plate products. Also, The GTR process results in the formation of new crystal grains in the crack region, which is crucial to crack healing.

Influence of hot rolling on the microstructure of lean duplex stainless steel 2101

In this work, the microstructure and the strain partitioning of lean duplex stainless steel 2101 (LDX 2101) during different hot-rolling processes are investigated by optical microscopy and electron-backscattered diffraction (EBSD). The results show that the LDX 2101 exhibits poor thermoplasticity at high temperature. The four-pass hot-rolled plates show fewer edge-cracking defects and superior thermoplasticity compared with the two-pass hot-rolled plates prepared at different temperature. The phase boundary is the weakest site in the LDX 2101. The cracks are initiated and propagated along the phase boundaries during the hot-rolling process. According to the EBSD analysis, the increase of the hot-rolling pass can dramatically improve the strain distribution in ferrite and austenite phases and promote the strain transmission in the constituent phases, thereby improving the coordinated deformation ability of the two phases. This effect further in- creases the thermoplasticity and reduces the formation of edge cracks in LDX 2101.

Formation Mechanism in Alloy Steel Rolling Process Using Thermo-mechanical Coupling Method

Based on the theory of elastic-plastic finite element method, the high-speed hot continuous rolling process of a billet is simulated and analyzed in vertical and horizontal passes. The billet is dragged into the passes by contact friction force between the billet and rollers. The rollers and billet are represented by respectively rigid and deformable bodies, and three-dimensional models are developed for the billet and rollers. The distribution of deformation field, effective strain, rolling force and temperature field are accurately calculated for the whole rolling process （including unstable and stable stages）. In addition, the rolling pressure on the width symmetry center is compared with that in the in-situ experimental measurements. It is revealed that various heat exchange phenomena among the billet, rollers and surroundings can result in unbalanced temperature distribution on the cross section. Rolling force and strain can change significantly when the billet is moved towards or away from the roller gap, and keep almost invariable in the stable stage. It is expected that the simulation results would be useful for practical manufacture and provide the theoretical foundation for improvement of process planning and optimization of process parameters.

Wave Processes and Mass Transfer on the Copper-Stainless Steel Interface under Solid Phase Bonding by High-Temperature Rolling

The paper presents the study of hierarchy of deformation wave-processes from nano- to macro-structural level, which takes place in dissimilar materials, bonded by high-temperature vacuum rolling in solid phase. The focus was on the processes that occur on the interface of the bonded materials: mass trasfer of impurities and alloying elements stimulated by deformation, the study of nano- and micro-hardness.

Self-Learning and Its Application to Laminar Cooling Model of Hot Rolled Strip

The mathematical model for online controlling hot rolled steel cooling on run-out table （ROT for abbreviation） was analyzed, and water cooling is found to be the main cooling mode for hot rolled steel. The calculation of the drop in strip temperature by both water cooling and air cooling is summed up to obtain the change of heat transfer coefficient. It is found that the learning coefficient of heat transfer coefficient is the kernel coefficient of coiler temperature control （CTC） model tuning. To decrease the deviation between the calculated steel temperature and the measured one at coiler entrance, a laminar cooling control self-learning strategy is used. Using the data acquired in the field, the results of the self-learning model used in the field were analyzed. The analyzed results show that the self-learning function is effective.

Optimal design of hot rolling process for C-Mn steel by combining industrial data-driven model and multi-objective optimization algorithm

A successful mechanical property data-driven prediction model is the core of the optimal design of hot rolling process for hot-rolled strips. However, the original industrial data, usually unbalanced, are inevitably mixed with fluctuant and abnormal values. Models established on the basis of the data without data processing can cause misleading results, which cannot be used for the optimal design of hot rolling process. Thus, a method of industrial data processing of C-Mn steel was proposed based on the data analysis. The Bayesian neural network was employed to establish the reliable mechanical property prediction models for the optimal design of hot rolling process. By using the multi-objective optimization algorithm and considering the individual requirements of costumers and the constraints of the equipment, the optimal design of hot rolling process was successfully applied to the rolling process design for Q345B steel with 0.017% Nb and 0.046% Ti content removed. The optimal process design results were in good agreement with the industrial trials results, which verify the effectiveness of the optimal design of hot rolling process.

Application of FEM to Hot Continuous Rolling Process for Inconel 718 Alloy Round Rod

A finite element model for coupled thermo-meehanical analysis has been developed in hot continuous rolling process for Inconel 718 alloy round rod with diameter of 45 mm. The stability of this alloy is discussed by integration of FEM and processing map reported in literatures. The result shows that the stability of Inconel 718 alloy is analyzed effectively during that process and good stability appears as the initial temperature is 960 ℃ and the initial velocity is from 0. 15 to 0.45 m · s^-1 or the initial temperature is 980 ℃ and the initial velocity is from 0. 15 to 0. 25 m · s^-1.

Numerical simulation on recrystallization behavior and microstructure evolution during hot continuous rolling process of 38CrMoAl steel rod

The control of microstructure during hot rolling process of steel is of great importance and will affect the properties of the steel products.According to the production line,a three-dimensional multi-field coupled finite element model of 24-pass continuous hot rolling process of 38CrMoAl steel rod is established using the finite element software MSC.Marc.Based on the recrystallization kinetics model and the grain growth model,a subroutine written in Fortran is introduced to calculate the recrystallization behavior and microstructure evolution of 38CrMoAl steel during the entire rolling process.The distribution and evolution of variables such as strain,temperature and recrystallization fractions during the rolling process are analyzed.The temperature variations and grain sizes at both the center and surface of the tested steel are compared with the experimental results.And it is found that the simulation results are in good agreement with the experimental ones,confirming the reliability of the established model.

基于深度置信网络的多模态过程故障评估方法及应用

传统的多模态过程故障等级评估方法对模态之间的共性特征考虑较少,导致当被评估模态故障信息不充分时,评估的准确性较低.针对此问题,首先,提出一种共性–个性深度置信网络(Common and specific deep belief network,CS-DBN),该网络充分利用深度置信网络(Deep belief network,DBN)的深度分层特征提取能力,通过度量多模态数据间分布的相似性和差异性,进一步得到能够反映多模态过程共有信息的共性特征以及反映每个模态独有信息的个性特征;其次,基于CS-DBN,利用多模态过程的已知故障等级数据生成多模态共性–个性特征集,通过加权逻辑回归构建故障等级评估模型;最后,将所提方法应用于带钢热连轧生产过程的故障等级评估中.应用结果表明,随着多模态故障等级数据的增加,所提方法的评估准确率逐渐增加,当故障信息充足时,评估准确率可达98.75%;故障信息不足时,与传统方法相比,评估准确率提升近10%.

不同除鳞工艺对热轧带钢热镀锌质量的影响

目的研究酸洗、湿法抛丸技术(Eco-Pickled Surface,EPS)、EPS+纤维刷工艺(EPS+plus)和干抛丸4种不同除鳞工艺对Q235B热轧带钢热镀锌质量的影响机理和规律,并将EPS和EPS+plus工艺处理后的热轧带钢在带钢热镀锌生产线上试制,实现大规模生产。方法采用粗糙度轮廓仪测量4种表面除鳞处理后的Q235B钢板表面粗糙度,利用扫描电镜分析表面形貌及氧化皮残留情况。通过实验室热镀锌实验,观察镀锌层表面形貌,利用场发射电子探针(EF-EPMA)分析锌层截面形貌及成分面分布;通过折弯实验评定锌层结合力;去除表面镀锌层,计算锌消耗量,观察脱锌后表面抑制层形貌,并用能谱对其进行成分分析。将Q235B热轧带钢在鞍钢金固EPS生产线上进行EPS和EPS+plus处理后,分别在热镀锌生产线进行镀锌和镀锌铝镁工业试制,并对生产试制卷进行力学、折弯及杯突检测,以评定质量。结果酸洗、EPS、EPS+plus和干抛丸4种工艺处理后钢板表面粗糙度分别为1.4442、3.3305、2.3964、4.3388μm。EPS处理试样表面未发现有氧化铁皮的残留,EPS+plus处理试样仅有极少量的氧化铁皮残留。EPS和EPS+plus工艺处理钢板热镀锌试样基体与锌层之间均能形成连续较致密的抑制层,锌层结合力评为1级,且锌消耗量较小,分别为148.3、123.5g/m^(2)。结论EPS和EPS+plus工艺处理后钢板镀锌质量优于酸洗和干抛丸工艺,EPS和EPS+plus工艺处理后在热镀锌生产线上试制的实验卷满足镀锌质量要求。

基于差分进化算法的热轧板坯工艺参数优化

针对热轧生产过程中工艺参数优化问题,提出了一种差分进化算法。首先,构建随机森林回归模型预测质量特征;然后,基于随机森林回归模型的工艺参数重要性排序结果选择待优化的工艺参数;最后,利用差分进化算法优化工艺参数并使用最优结果替换待优化的工艺参数。文章提出以缺陷相对发生率平均降低值和平均降低率作为评价指标,对比研究优化前后的结果,与其他优化算法相比,差分进化算法达到了最优性能。应用分析表明,所提算法进行工艺参数优化后,单位板坯中的缺陷个数均少于25,算法执行平均用时为8.57 s,具有良好的可操作性与应用推广价值。

超吸水织物的制备及性能研究

以丙烯酸为单体,过硫酸钾、亚硫酸氢钠为氧化还原引发剂,与聚乙烯醇共混,采用溶液聚合法制备了丙烯酸高聚物溶液,浸轧丙纶热熔无纺布织物,经烘干得到超吸水织物,通过傅里叶变换红外光谱仪、场发射扫描电子显微镜、同步热分析仪对超吸水织物的结构、形貌和热性能进行分析,考察了聚合反应水浴温度、丙烯酸中和度、聚乙烯醇添加量、带液率对吸水倍率的影响,并对吸水机理进行探讨。结果表明:在聚合反应水浴温度为75℃,丙烯酸中和度75%,聚乙烯醇添加量(对单体)为5%(质量分数),带液率为500%,烘干温度为120℃条件下,制备的超吸水织物吸蒸馏水倍率为109.82g/g。

基于时域卷积网络的精轧出口厚度预测

以精轧过程为研究对象,引入时域卷积网络算法,构建了基于时域卷积网络的精轧出口厚度预测模型。利用时域卷积网络模型提取精轧过程时序数据的特征信息,通过优化模型结构和参数,提升精轧出口厚度预测性能。实际钢种数据集仿真实验结果表明,相较于传统方法,本文所提出的时域卷积网络算法在均方根误差、平均绝对百分比误差及决定系数等评价指标方面存在较大优势,可为现场工程师提供重要的决策信息。

B500BD13mm带肋钢筋四线切分轧制生产工艺开发

介绍了石横特钢棒材厂英标B500BD13mm热轧带肋钢筋四切分轧制生产工艺的设计。针对顶出口、切分刀粘铁、力学性能不稳定以及成品尺寸不符合标准问题,分别从提高轧机刚性、优化导卫结构、提高温度工艺控制精度和优化孔型、调整机架间张力的措施着手,实现了热轧带肋钢筋四切分的稳定轧制,最终形成工业化批量生产,年创效360万元,产品质量满足用户需求。

轧钢热装效益的提升探讨

通过提高组织优化、信息化和数字化水平,提出了一系列措施实现资源配置调整、调度协同化、技能培训、引入智能调度系统、数据集成与共享以及数据驱动的决策等,有助于增加企业经济效益,并建议与制造部门密切合作,不断追求优化和改进,旨在提升永钢集团轧钢厂的热装效益。

黏胶/ES纤维热轧消毒吸附干巾表层材料的制备与性能分析

为制备兼具良好力学性能和导流性能的消毒吸附干巾表层材料,将黏胶纤维和ES纤维混合,通过热轧非织造加固工艺制备黏胶/ES纤维热轧消毒吸附干巾表层材料。通过单因素试验,探讨黏胶纤维和ES纤维混合比例及热轧温度对材料力学性能和导流性能的影响。结果显示:纤维混合比例与热轧温度均显著影响材料的力学性能与导流性能,优化的工艺参数为黏胶纤维和ES纤维质量比20/80、热轧温度135℃。采用优化工艺参数制备的热轧消毒吸附干巾表层材料,其纵横向断裂强力分别为88.16 N和36.82 N,吸液率为751%,扩散长度为18.1 cm,渗水面浸湿时间为2.25 s,上下层吸水速率分别为26.19%/s和65.61%/s,上下层液态水扩散速度分别为3.96 mm/s和6.54 mm/s,单向传递指数为962,兼具良好的力学性能和导流性能。

热连轧过程机架间运动板带动特性研究

研究了热轧过程机架间运动板带动力学特征及其影响因素。基于热轧过程板带张力形成机理,考虑机架间板带张力建立了动态张力模型;同时,考虑热轧机活套辊对运动板带的支撑作用,基于Hamilton理论建立了运动板带等效运动梁模型,并基于四阶Galerkin截断法对偏微分方程进行离散化,得到系统四阶常微分方程组。仿真分析机架间板带张力、速度和活套辊支承刚度对运动板带动力学特性的影响,以及运动板带在辊系振动引发的速度摄动下振动特征和影响规律。结果表明:张力、板带速度和活套支撑辊刚度均影响板带动力学模态特征,且活套辊支撑作用可降低板带振动幅值;在热轧工艺范围内,调整板带张力和速度对运动板带的稳定性影响不大;辊系振动造成板带运动速度呈摄动特征,且摄动频率和幅值与板带振动强度关系密切。该研究对热轧过程机架间运动板带稳定性分析和活套控制设计提供参考。