Deep learning for predictive mechanical properties of hot-rolled strip in complex manufacturing systems

Higher requirements for the accuracy of relevant models are put throughout the transformation and upgrade of the iron and steel sector to intelligent production.It has been difficult to meet the needs of the field with the usual prediction model of mechanical properties of hotrolled strip.Insufficient data and difficult parameter adjustment limit deep learning models based on multi-layer networks in practical applications;besides,the limited discrete process parameters used make it impossible to effectively depict the actual strip processing process.In order to solve these problems,this research proposed a new sampling approach for mechanical characteristics input data of hot-rolled strip based on the multi-grained cascade forest(gcForest)framework.According to the characteristics of complex process flow and abnormal sensitivity of process path and parameters to product quality in the hot-rolled strip production,a three-dimensional continuous time series process data sampling method based on time-temperature-deformation was designed.The basic information of strip steel(chemical composition and typical process parameters)is fused with the local process information collected by multi-grained scanning,so that the next link’s input has both local and global features.Furthermore,in the multi-grained scanning structure,a sub sampling scheme with a variable window was designed,so that input data with different dimensions can get output characteristics of the same dimension after passing through the multi-grained scanning structure,allowing the cascade forest structure to be trained normally.Finally,actual production data of three steel grades was used to conduct the experimental evaluation.The results revealed that the gcForest-based mechanical property prediction model outperforms the competition in terms of comprehensive performance,ease of parameter adjustment,and ability to sustain high prediction accuracy with fewer samples.

Stream Surface Strip Element Method and Simulation of Three-Dimensional Deformation of Continuous Hot Rolled Strip

A new method,the stream surface strip element method,for simulating the three-dimensional deformation of plate and strip rolling process was proposed.The rolling deformation zone was divided into a number of stream surface(curved surface)strip elements along metal flow traces,and the stream surface strip elements were mapped into the corresponding plane strip elements for analysis and computation.The longitudinal distributions of the lateral displacement and the altitudinal displacement of metal were respectively constructed to be a quartic curve and a quadratic curve,of which the lateral distributions were expressed as the third-power spline function,and the altitudinal distributions were fitted in the quadratic curve.From the flow theory of plastic mechanics,the mathematical models of the three-dimensional deformations and stresses of the deformation zone were constructed.Compared with the streamline strip element method proposed by the first author of this paper,the stream surface strip element method takes into account the uneven distributions of stresses and deformations along altitudinal direction,and realizes the precise three-dimensional analysis and computation.The simulation example of continuous hot rolled strip indicates that the method and the model accord with facts and provide a new reliable engineering-computation method for the three-dimensional mechanics simulation of plate and strip rolling process.

Elastoplastic 3D Deformation and Stress Analysis of Strip Rolling

An elastoplastic method for analyzing the 3D deformation, stress and transverse distribution of tension stress during cold strip rolling is developed. The analysis is based on the elastoplastic variational principle in which a kinematically admissible velocity field is constructed with the lateral flow function as an unknown function. The stress distribution and volume strain distribution are obtained by solving the simultaneous equations formed by the longitudinal differential equation of equilibrium and constitutive equations. The lateral flow function is determined by minimizing the total energy dissipation rate. Experimental investigation was carried out on a reversible cold mill. The front tension stress distributions in cold rolled strips were measured by a multi roll segmented tension sensing shapemeter. The calculated results are in good agreement with the measured ones.

“Quartus scale” of hot-rolled strip steels and its formation mechanism

The types and growth of various oxide scales formed during the different phases of the production of hotrolled strip steel products are reviewed. Similarities and differences between the ＂tertiary scale＂ on the surface of carbon steels at high temperatures and the oxide scale on pure iron are compared. The micro-structural features of the ＂final oxide scale＂ on the surface of strip steels at room temperature as well as the relationship between these features and the position of the steel coil （plate） and the subsequent processes of recoiling, temper rolling and trimming, etc. are summarized. The actual oxide scales retained on the commercial hot-rolled strip steels at room temperature have been proposed to define as ＂ quartus scale＂ for the first time. The micro-structural development and phase transformation of the initial ＂tertiary scale＂ during and after cooling and coiling are described. The reasons for the ＂tertiary scale＂ on carbon steels differing from the oxide scale formed on pure iron, and the major influencing factors in the formation of various types of ＂quartus scales＂ are analyzed from both thermodynamic and dynamic viewpoints. The development mechanism of ＂ quartus scales＂ is discussed and the potential effects of the ＂ quartus scale＂ state （thickness, constitution, structure and defects）, on the rusting and pickling properties of commercial hot-rolled strip steel, as well as on the mechanical properties of oxide scales are analyzed.

A dynamic large-deformation particle finite element method for geotechnical applications based on Abaqus

In this paper,the application of Abaqus-based particle finite element method(PFEM)is extended from static to dynamic large deformation.The PFEM is based on periodic mesh regeneration with Delaunay triangulation to avoid mesh distortion.Additional mesh smoothing and boundary node smoothing techniques are incorporated to improve the mesh quality and solution accuracy.The field variables are mapped from the old to the new mesh using the closest point projection method to minimize the mapping error.The procedures of the proposed Abaqus-based dynamic PFEM(Abaqus-DPFEM)analysis and its implementation in Abaqus are detailed.The accuracy and robustness of the proposed approach are examined via four illustrative numerical examples.The numerical results show a satisfactory agreement with published results and further confirm the applicability of the Abaqus-DPFEM to solving dynamic large-deformation problems in geotechnical engineering.

Effect of Deformation between Stands on the Strip Shape in Hot Rolling

A theoretical model about the secondary deformation is developed by the combination of analytical and experimental approaches. A system simulation based on the model is completed to predict the strip profile after the interstand deformation. On the other hand, comprehensive experiments and quantitative comparisons are made to calibrate the model for a wide variety of products. As a result, the correction of the model has been verified by the actual rolling data from production mill and it is helpful to improve the strip shape control.

Hot-rolled strips of up to 19 mm in thickness and their processing to helically welded large diameter pipes of grade X80

Hot-rolled wide strip for production of large diameter,heavy gauged(up to 19 mm) helical line pipe grade X80 was a priority development over the last three years.Microstructure,texture and mechanical properties of strips have been characterised.Also the welding conditions have been simulated.The favourable microstructure is achieved by the proper selection of an appropriate chemical composition of low carbon content and increased niobium micro alloying in combination with suitable strictly controlled hot-rolling parameters.The addition of niobium in combination with the adjustment of other alloying elements increases the recrystallisation stop temperature and thus makes it possible to apply a high temperature processing(HTP) concept.The homogeneous bainitic microstructure across the strip gauge is then formed during accelerated cooling on the run-out table of the hot-rolling mill.All results indicated excellent properties of these hot strips which make it suitable for spiral pipes of grade X80 for example 18.9mm×Φ1 220 mm at dimension.

Mill scale structure and damp heat corrosion performance of four 510L hot-rolled strips

In this study, the matrix structure, state and composition of the mill scales of four typical domestically made 510L hot-rolled strips were observed and analyzed by means of optical microscopy （OM） ,scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The corrosion behavior of the steels with and without mill scales were investigated by means of hot-humid corrosion tests under the condition of relative humidity （ RH ） of 95% at 50℃ and 70℃, respectively. The results show that the matrix structures, state, composition and thickness of mill scales vary in the strips. The rusting starting time of the specimens with scales is generally a bit longer than that of the specimens without scales, but their corrosion mass-gain is higher. For these two kinds of specimens ,their corrosion rate increases significantly with the increase of temperature. The rusting behavior of the 510L strips produced by various plants is different due to the variations of hot-rolling processes and designed chemical compositions. Various relevant aspects should be taken into account in the evaluation of the corrosion behavior of hot-rolled strips.

STUDY ON STRIP AND ROLL DEFORMATION COUPLING OF COLD STRIP ROLLING ON 4-H MILL

The cold strip rolling process on a 4 h mill is studied by coupling the 3 dimensional plasticity deformation of the strip with the elastic deformation of the rolls. On the conditions of that the width to thickness ratio of the strip is 660 and the exit strip shapes are respectively edge wave, centre wave and good, the computed results of the transverse distributions of the roll gap, the rolling pressure, the inter roll pressure, and the front and back tension agree with the experimental results well. The studing methods and the studied results are of great importance to forming shape theory and guiding the development of shape control technology.

Inclusion and its deformation behavior in 304 stainless steel

Non-metallic inclusion is the main reason for the presence of surface defects in cold-rolled steel strip. In this study, the composition, morphology, and size of the non-metallic inclusion in hot-rolled 304 stainless steel strips are analyzed. Cold-rolled 304 stainless steel strips with different cold-rolling reduction have been prepared, and the morphology and size of inclusion in these cold-rolled strips are also analyzed. Furthermore, the deformation behavior of a non-metallic inclusion during the cold-rolling process is studied. The results show that CaO-SiO2- MgO-Al2 O3, a kind of brittle compound oxide,is the main type of inclusion in hot-rolled 304 stainless steel strips. During the cold-rolling process, ductile deformation of this type of inclusion is not obvious, where large inclusions are crushed, and the average size of inclusions in cold-rolled strips decreased while the cold-rolling reduction increased.

A test method for analyzing the deformation of landslide model

In order to study the overall deformation of geotechnical model conveniently,the worksite of landslide bridge foundation reinforced by the front and rear row anti-slide piles in Chenglan railway was taken as an example.On the basis of shaking tabe test of a 1/40 reduced scale model,the landslide deformation caused by vibration waves was monitored through burying self-made phosphor bronze strips in soil.Combined with the horizontal and vertical coordinates of the bending strain points on the phosphor bronze strips,the digital matrix was converted by applying Renka Cline random matrix generation method,and the two-dimensional contour plots were drawn based on it.The results showed that the two-dimensional contour plots reflected the basic law of landslide deformation reasonably,and it revealed the evolution process of landslide deformation and failure.The research conclusions were consistent with the test phenomenon,which met the basic requirements of overall deformation analysis of landslide model.This proposed method can monitor multiple cross sections and was practical for model test.

基于可变形卷积和注意力的带钢瑕疵识别方法

带钢生产中瑕疵检测的准确性对于其质量的保证有着至关重要的意义。本文针对带钢表面瑕疵检测中的瑕疵种类复杂、背景干扰严重、瑕疵样式间面积形态差异较大等问题,提出了一种基于ResNet50改进的结合多尺度变形卷积和注意力的带钢表面瑕疵分类识别方法。首先通过细化ResNet50中BottleNeck结构的卷积块为一组多尺度卷积以扩大感受野,然后引入可变形卷积代替组中的卷积核,使网络在训练中捕捉不同形态尺度的瑕疵特征。最后在网络中引入增强注意力模块,使网络可以关注到通道与空间之间的信息,将其联合起来从而关注到更重要的通道和空间位置。通过对比实验表明,本文提出的方法在带钢的表面瑕疵分类识别上精确度优于现有方法,可以应用于企业实际的带钢的工业生产中。

潮汐效应对沿海多条带时序InSAR地表形变监测的影响

潮汐效应对沿海大范围、高精度的合成孔径雷达干涉测量(Interferometric Synthetic Aperture Radar,InSAR)技术地表形变监测的影响不可忽略.潮汐效应中的固体潮(Solid Earth Tide,SET)位移和海洋潮汐负荷(Ocean Tide Loading,OTL)位移会在时间和空间域上对沿海大范围InSAR地表形变监测产生分米级的误差,而且不同条带中地表潮汐形变时空差异性会对多条带InSAR影像拼接产生较大误差.本文针对沿海地区多条带InSAR形变时序,重点分析了潮汐效应在不同条带InSAR地表沉降监测中的影响,并采用多种潮汐位移估计方法对多条带地表潮汐形变进行改正.结果表明,研究区域不同条带时序InSAR中地表潮汐形变具有较大的时空差异性,其造成沿海地区相邻条带时序InSAR地表沉降速率差异能达到1~2 cm·a^(-1);通过固体潮模型、海潮负荷模型或GPS参考站网海潮位移改正,能够消除不同条带中地表潮汐形变时空差异性对时序InSAR形变结果拼接产生的空间高阶非线性误差,弥补了传统拼接方法在拟合潮汐位移偏差的不足.在大气延迟误差改正的基础上,时序InSAR形变残差的标准差(Standard Deviation,STD)由潮汐改正前的2.3 cm减少至0.75 cm;本文研究揭示了沿海地表潮汐形变改正对多条带时序InSAR形变结果拼接的重要性,可大幅提高沿海地区广域时序InSAR地表形变监测的精度.

Prediction of hot-rolled strip crown based on Boruta and extremely randomized trees algorithms

The quality of hot-rolled steel strip is directly affected by the strip crown.Traditional machine learning models have shown limitations in accurately predicting the strip crown,particularly when dealing with imbalanced data.This limitation results in poor production quality and efficiency,leading to increased production costs.Thus,a novel strip crown prediction model that uses the Boruta and extremely randomized trees(Boruta-ERT)algorithms to address this issue was proposed.To improve the accuracy of our model,we utilized the synthetic minority over-sampling technique to balance the imbalance data sets.The Boruta-ERT prediction model was then used to select features and predict the strip crown.With the 2160 mm hot rolling production lines of a steel plant serving as the research object,the experimental results showed that 97.01% of prediction data have an absolute error of less than 8 lm.This level of accuracy met the control requirements for strip crown and demonstrated significant benefits for the improvement in production quality of steel strip.

基于DeForm的板条冲压扭曲成形数值模拟

运用DeForm-3D软件进行数值模拟,分析不同尺寸规格板条在扭曲成形过程中的损伤值、等效应力、等效应变、金属流动速率及载荷-行程的影响规律。通过18组模拟数据表明,夹具与板条的夹持力(夹具与板条摩擦力)一定时,板厚t较薄,板条扭曲容易失稳;t较厚,不易失稳但易破裂。板条扭曲成形过程中金属流动速率与板条宽度正相关,与板条厚度关系不大。板料变形区中间部分变厚,边缘部分变薄,即板条扭曲变形边缘会伸长,属于伸长类变形;中心线附近会缩短,属于压缩类变形。

铝合金板料成形间距对逐点连续电磁成形过程的影响规律

电磁成形具有高速成形和提高材料塑性成形性能的特点,非常适用于准静态下难加工轻质铝合金材料的成形。在电磁系统中加入集磁器可以实现对工件的局部加工,但当电磁集中在小区域内多次成形时,由于两个成形点的距离较小,存在局部变形相互影响的区域,从而影响板料成形的均匀性。为研究逐点连续电磁成形过程中局部变形之间的相互作用机理,采用数值模拟结合实验验证的方法,探究了金属板料小区域逐点连续电磁成形过程中的变形行为,揭示了成形间距对板料成形涉及的电磁力、应变和最终成形效果的影响规律。研究结果表明,在单次电磁成形时,板料受到的电磁力呈环状分布,成形点中心受到径向与切向压应变和轴向拉应变,成形点四周受到径向拉应变和轴向与切向的压应变。在多次成形时,随着两成形点间距减小,板料在第二次成形时受到变形区的影响,影响间距为14 mm,板料中心所受的径向压应变和轴向拉应变增大,板料电磁力逐渐增大。第二成形点中心的成形高度随着两成形点间距的增加逐渐增加,两个成形点衔接处的凹槽深度也越深,而两个成形点衔接处的径向拉应变随着成形间距的增加表现为先增大后减小的趋势。本研究为在铝合金板料多点电磁成形过程中两点变形间距对电磁力和成形效果的影响提供了理论依据。

改进YOLOv8 的带钢缺陷检测

针对带钢表面缺陷检测精度不足的问题,提出一种改进的YOLOv8n检测模型。基于可变形卷积对Head网络中的C2f模块进行了重新设计;通过利用采样点的可变性,有效提高了对表面不规则缺陷的检测能力。添加多头自注意力机制捕捉不同的关注点,从而提供全面且多样化的特征表示,进一步增强模型的检测性能。拼接Backbone和Head的特征,提升特征的质量和丰富度,解决缺陷局部信息丢失问题。在NEU-DET带钢数据集的实验验证中,该方法在平均精度和mAP50上较YOLOv8n分别提升了5.6和2.2个百分点。值得注意的是,裂纹缺陷的检测精度和mAP50分别提升了15.2和9.9个百分点,效果显著。

在线连续退火对TA4箔带材性能的影响

采用氩气保护在线连续退火炉对冷轧变形后0.12 mm厚度TA4箔带材进行退火试验,并进行拉力试验和金相组织试验,分析不同退火温度下TA4箔带材的力学性能和金相组织变化。研究结果表明,在550~610℃范围内退火,随着温度的升高,TA4箔带材抗拉强度(Rm)和屈服强度(Rp0.2)连续下降,而伸长率(A50)持续升高;在此温度范围内TA4箔带材处于不完全再结晶状态,金相组织呈现变形组织和部分等轴晶的混合状态,回复和部分再结晶是引起强度降低、塑性提高的原因;得到满足3C电子产品对TA4箔带材性能需求的在线退火参数,TA4箔带材显现出良好的强度和塑性。

基于EMD能量熵的受电弓滑板振动特性分析与诊断

结合检测数据,对高速运行下受电弓滑板振动特性进行研究,提出了基于经验模态分解(EMD)的滑板异常振动诊断方法。首先,开展国内外弓网振动评价体系研究。其次,通过分析线路试验数据,得出高速运行时DSA380型受电弓滑板垂向加速度能量主要集中在278、550 Hz附近,且振动主频为278 Hz。通过ANSYS计算滑板垂向第3、5阶模态频率为279.65、531.47 Hz,与线路试验结果相近。该结果反映我国弓网振动评价体系主要表征受电弓碳滑板的弹性振动,且DSA380型受电弓滑板高速运行时振动响应主频为滑板3阶模态频率。最后,应用经验模态分解对振动数据进行自适应分解得到若干本征模态函数(IMF)。当滑板异常振动时,能量集中分布于滑板3阶模态频率处,能量熵较正常状态大幅减小,因而可采用能量熵作为评价指数,评判滑板工作状态。

条带充填开采巷道围岩变形及顶板导水裂隙带实测研究

以常村煤矿条带充填巷道群集中开采为宏观技术背景,依托常村煤矿CTS2-01工作面充填开采工程实践,对现场充填体强度、顶底板移近量和导水裂隙带发育高度进行实测。结果表明,充填膏体试件强度随养护时间增加而增加,井下充填体试件不同期龄的平均抗压强度比地面充填站的更高,且标准差和方差也更大;巷道变形最大为67 mm,平均变形量不超过0.5 mm/d,说明条带充填开采后工作面主巷道变形量很小,不影响正常生产;综合顶板窥视及注水试验结果判断认为,条带充填开采后,工作面顶板最大导水裂隙带发育高度小于4.0 m。研究成果可为条带式充填开采技术的推广应用提供一定的技术参考与经验借鉴。