Plate Rolling Research Articles

Rolled Thickness Prediction for Titanium/Steel‐Clad Plates Based on Combined Method of Theoretical and Neural Network

To address the issue of low precision in rolled thickness prediction for titanium/steel‐clad plates, theoretical calculation and back propagation (BP) neural network prediction models are established based on the slab method and the rolled measured data, respectively. Furthermore, to solve the model's black‐box problem while also improving thickness prediction accuracy, three combined prediction models are built using the principles of compensating multiplicative error, additive error, and average error based on the model's advantages and features for thickness prediction. During the modeling phase, 1925 groups of manufacturing data for titanium/steel‐clad plate rolling are selected and normalized to form the data set. The trial‐and‐error method is used to determine the optimal network structure for the BP neural network. The model's performance is assessed by calculating the mean square error, mean absolute error, and coefficient of determination (R2) and comparing the relative errors in prediction outcomes across different models. In the results, it is demonstrated that the average error combined model (Combined Model III) performs better and predicts more accurately.

Strain Hardening of 1565ch, AMg6, 01570, and 1580 Aluminum Alloys in the Process of Cold Rolling of Plates

Strain Hardening of 1565ch, AMg6, 01570, and 1580 Aluminum Alloys in the Process of Cold Rolling of Plates

Vertical vibration analysis of rolling interface based on dynamic rolling force with variable friction characteristics

This study investigates the impact of variable friction characteristics at the rolling interface on the vertical vibration of plate and strip rolling mills. Based on the optimized Karman equilibrium theory, a dynamic rolling force model considering the front and back tension, elastic stretching, and rolling speed was established. The amplitude-frequency response equation of rolling mill system is solved by multi-scale method, and the influence of main parameters on vertical vibration of rolling mill system is analyzed. The results show that the increase of the first stiffness coefficient of dynamic rolling force leads to the decrease of the principal common amplitude of the system. On the contrary, when the third stiffness coefficient increases, the system exhibits a jump phenomenon. When the third stiffness coefficient of dynamic rolling force is reduced within a certain range, a stable and unique solution is obtained without jumping phenomenon. Moreover, the smaller the damping coefficient of the upper and lower roller system is, the larger the vibration amplitude is and the jump phenomenon occurs. Decreasing the external disturbance force can effectively reduce the system’s vertical vibration amplitude and suppress the resonance. In addition, with the change of external disturbance force, the roll system of the rolling mill shows a variety of complex motion states, such as periodic motion, double-periodic motion, and chaotic motion. The research results provide an effective theoretical reference for the suppression of vertical vibration of rolling mill.

Research on the Mechanism of Oxygen-Induced Embrittlement Fracturing in Industrial Electrolytic Nickel.

In this study, severe cracking occurred during an investigation of the direct hot rolling of industrial electrolytic nickel plates. To determine the cause of hot-rolling cracking, the microstructure phase composition was analyzed through the utilization of various techniques, including optical microscopy, scanning electron microscopy, electron backscattering diffraction, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and electron probe micro-analysis. The comparative microstructural analysis took place between specimens heat treated in atmospheric and vacuum environments. The characterization and analysis of the hot-rolled plates considered the crack microstructure and fracture morphology. It was shown that holes appeared along the large angular grain boundaries after annealing at 1100 °C for 8 h. Possible reason: In a high-temperature environment, the decomposition of residual additives in the electrolytic nickel releases oxidizing gases, which oxidizes the grain boundaries. The reaction with carbon diffused into the grain boundaries and produced carbon monoxide gas, which induced holes and severely reduced the grain boundary plasticity. The heat treatment time did not need to be very long for severe grain boundary degradation to occur. After severe cavitation, the electrolytic nickel was severely cracked at grain boundaries cracks due to a shear force, and brittle fractures occurred along grains with very low plasticity.

Bonding enhancement of cold rolling TA1 P-Ti/AA6061 composite plates via surface oxidation treatment

TA1 P-Ti/AA6061 composite plate was produced by oxidizing the surface of the titanium plate and adopting a cold roll bonding process. The results revealed that the oxide film (Ti6O) prepared on the surface of TA1 pure titanium was easy to crack during the cold roll bonding, thereby promoting the formation of an effective mechanical interlock at the interface, which can effectively reduce the minimum reduction rate of the composite plates produced by cold rolling of titanium and aluminium plates. Moreover, the composite plate subjected to oxidation treatment exhibited high shear strength, particularly at a 43% reduction rate, achieving a commendable value of 117 MPa. Based on oxidation treatment and different reduction rates, the annealed composite plates at temperatures of 400, 450, and 500 °C displayed favorable resistance to interface delamination, highlighting their remarkable strength−plasticity compatibility as evidenced by a maximum elongation of 31.845%.

Effect of ultra-high temperature treatment on the rolled pure molybdenum for nuclear thermal propulsion

Molybdenum (Mo)-based uranium dioxide (UO2) fuel is considered one of the most promising fuel forms for deep-space exploration. The rolling process has been proposed for the preparation of Mo matrix due to its excellent performance. However, there has been limited research on the ultra-high temperature stability of Mo matrix used in nuclear thermal propulsion (NTP). Therefore, in this study, annealing experiments were carried out on rolled Mo plates within a relatively wide temperature range of 1200 to 2300 °C for 1 h to investigate the effects of temperature on the phase composition, microstructure, and mechanical property. The results showed that, despite the body-centered cubic structure of the Mo plates remaining unchanged without undergoing phase transition after high-temperatures, the intensity of the crystal diffraction peaks experienced a significant increase. The preferred growth orientation shifted from the (110) direction at lower temperatures to the (200) direction at 2300 °C. The grain shape of the rolled Mo plates changed from elongated to equiaxed after annealing, and the grain size increased from the initial 1 μm to tens of microns. No discernible surface pores or fracture bubbles were observed when annealed at 1200 to 2100 °C. However, subsequent annealing at 2300 °C revealed a proliferation of polyhedral bubbles, ranging in size from tens of nanometers to several microns, distributed both in grain boundaries and within grains. Nevertheless, there is no apparent change in the density from 1200 to 2300 °C. Bright-field TEM micrographs show that after annealing at 2300 °C, the dislocation density is significantly reduced, and the dislocation shape evolves from screw dislocation to long and straight line. In addition, the Vickers hardness value of the rolled Mo plates undergoes a significant decrease, from 247.1 to 199.6 Hv, after annealing at 1200 °C. Subsequently, in the temperature range of 1200 to 2300 °C, a gradual decline in the hardness value is observed. This work will deepen our understanding of the high-temperature resistance of rolled Mo plates and provide data to support their applications in ultra-high-temperature conditions.

Grain boundary-mediated strain response mechanism of AZ31 gradient- structure Mg alloy plate under uniaxial tensile loading

The changes in strain gradient induced by grain boundaries are crucial for enhancing the plasticity of gradient magnesium (Mg) alloys. The change of strain distribution influence by grain boundaries during plastic deformation of the gradient structure was examined. In this paper, the gradient structure AZ31 Mg-alloy plate with the surface fine grain (FG) to the center coarse grain (CG) was fabricated using hard plate rolling (HPR). The microstructure and strain distribution of Mg-alloy with a gradient structure were analyzed by electron backscatter diffraction (EBSD) and Digital image correlation (DIC) during uniaxial tensile. The findings indicate that the gradient structure sample (GS sample) displays a uniform strain distribution during the tensile process. Coarse-grain sample (CG sample) have obvious strain concentration, which leads to premature fracture. Based on EBSD characterization, low-angle grain boundaries (LAGBs) accumulates in the CG during plastic deformation. Orientation of CG tends to the (0001) basal. At the same time, the density of geometrically necessary dislocations (GNDs) inside CG has changed, which improves the Heterogeneous deformation induced (HDI) stress of gradient structure. During the uniaxial tensile, LAGBs accumulates in CG and changes the strain distribution of the gradient structure, which induces the accumulation of GNDs, and hence improving the properties of the GS Mg-alloy. These findings unveil the mechanism of strength-plasticity synergism of GS alloys from a new perspective and offer insights into the application of GS in Mg-alloys.

Double effects of recrystallization behavior on grain morphology evolution and mechanical properties of Al/Mg/Al composite plate by hard plate rolling

Enhancing the bonding strength, optimizing the microstructure and refining the properties represent effective strategies for the fabrication of heterogeneous composite plates. In this study, composite plates of Al/Mg/Al were fabricated through hard plate rolling (HPR) with a reduction in rolling ranging from 40 ​% to 80 ​%. The research primarily concentrates on the substrate in the influence of rolling dynamic recrystallization (DRX) behavior on the grain morphology evolution and mechanical properties of AZ31 magnesium alloy sheets during the process. The findings indicate that at a compression amount of 60 ​%, the composite plate exhibits an ultimate tensile strength (UTS), a maximum elongation (EL) of 12.5 ​%, and improved interface bonding. Comparative analysis reveals the occurrence of DRX on the Mg side, resulting in the formation of small DRXed grains being generated. With an increase in reduction, DRX is facilitated, leading to an initial rise and subsequent decline in the proportion of DRXed grains. The proliferation of fine grains hinder dislocation movement, thereby reinforcing composite plate. Moreover, an elevation in the degree of recrystallization enhances the initiation of non-basal slip and enhances the plasticity of sheet metal. This study offers valuable scientific guidance and technical assistance for the production of forming high-quality Mg–Al composite plates.

Second phase and matrix texture evolution influence mechanical properties of Al-Mg-Al composite plate by HPR with annealing temperature

Annealing treatment can determine the quality of heterogeneous composite plate by regulating the matrix and interface structures and interlayer bonding ability. Al-Mg-Al composite plate was used as an example. Al-Mg-Al composite plate was rolled with 50 % reduction by hard plate rolling. After that, it was annealed at 250 ℃, 300 ℃, 350 ℃ and 400 ℃ for one hour respectively. Through microstructure observation and performance test, the results show that the reaction phases of Al3Mg2 and Al12Mg17 were formed at the interface during annealing treatment. As the temperature continued to climb, yield strength and elongation after fracture of Al-Mg-Al composite plate showed a trend of increasing first and then decreasing, in addition, the tensile strength gradually decreased. As temperature reached 300 °C, its performance reached the best, the tear strength increased to 0.367 KN, and yield strength and elongation reached 172 MPa and 14.5 %, respectively. The study showed that although annealing temperature didn't change types of texture configuration of magnesium alloy, it affected the grain growth, resulting in the change of base surface texture and the overall performance of heterogeneous composite plate. This research provides a theoretical basis for precise regulation of microstructure and comprehensive performance of heterogeneous composite plate by annealing treatment.

Effects of Y2Zr2O7 particles and rolling deformation process on the mechanical properties and heat load behavior of W–Y2Zr2O7 plate

This paper addresses the significant requirements in China's fusion engineering and investigates the preparation technology and performance characterization of high-performance tungsten-based materials used as PFMs. The rolled W–Y2Zr2O7 plate were prepared through sintering and subsequent rolling, and steady-state heat load assessment was conducted under fusion device working conditions. Additionally, the change in mechanical behavior of the rolled plates was investigated across different surfaces. The results also revealed that the rolling plate exhibited a DBTT between RT and 200 °C, with more superior mechanical properties along the RD direction. The flat-plate W–Y2Zr2O7/Cu components demonstrated the ability to withstand 1000 heat load cycles at 10 MW/m2 without cracking, indicating favorable thermo-mechanical performance as PFMs. These findings serve as a valuable reference for the fabrication of tungsten-based materials in fusion engineering.

Fatigue crack propagation anisotropy of an Al–Zn–Mg–Cu super-thick plate

The fatigue crack propagation (FCP) rate is an important performance index in the aerospace industry for the safe lifespan evaluation. In this study, the FCP anisotropy of an Al–Zn–Mg–Cu super-thick rolled plate was analyzed. The results show that as the depth increases, the FCP anisotropy gradually becomes significant especially in the low ΔK region. The specimens tested along the transverse direction exhibit lower FCP rate than those tested along the rolling direction in the low ΔK region, which is related to the difference in the grain shape and grain orientation. More specifically, the crack is easy to deflect along the grain boundaries in the deformed grains when loading along the transverse direction. Meanwhile, more obvious grain orientation deviation on both sides of the crack can cause larger angle deflection, longer FCP path, and lower FCP rate. In the Paris region, the FCP anisotropy is not obvious regardless of thickness. The reason is that the main influencing factor is controlled by strength in this region, while the strength anisotropy is very limited leading to this similarity.

Digital Model of Automatic Plate Turning for Plate Mills Based on Machine Vision and Reinforcement Learning Algorithm

Plate turning is an essential step in the plate rolling process. The traditional control mode relies on the manual observation of billets and mainly manual operation. Manual plate turning becomes an external disturbance of the automatic control system of plate mills, which reduces the reproducibility and accuracy of the rolling process. The automatic plate turning function is urgently needed to improve the control level of the rolling line. In this paper, based on the improved image processing algorithm, the position and angle information of the billet conversion process are detected in real time, and the real-time processing of detection data in a complex production environment is realized. Based on the change in the billet rotation angle in the actual plate turning process, a mathematical model is constructed to simulate the plate turning process. On this basis, the digital model and optimization algorithm for automatic plate turning based on reinforcement learning are established, and the automatic optimization of plate turning speed and accuracy is completed. The field application of data-driven plate turning systems replaces manual plate turning control. The plate turning angle detection error of the system is ≤2°. The average plate turning time of each billet is greatly shortened compared with manual plate turning mode, and the fastest time can be shortened by more than 1 s, which greatly improves the production efficiency and is of great significance for improving the automatic control level and digital upgrade of plate mills.

Effects of normalizing process on microstructure, texture, and precipitates of Sn bearing oriented silicon steel

Low temperature heating process of the slab has become the mainstream process for producing high quality oriented silicon steel due to its environmental protection, low cost, and high yield. For this process, the number of inhibitors is less and the size is large, resulting in insufficient inhibition, coarsen grains during primary recrystallization, and insufficient driving force for secondary recrystallization, which reduces the magnetic properties of the product. These shortcomings can be improved by optimizing the inhibitors and normalizing processes. The effects of normalizing processes on the microstructure, texture, and precipitations of low-temperature oriented silicon steel containing Sn were studied by OM, SEM, TEM, and EBSD with Fe–3%Si hot-rolled plate as initial material. The experimental results show that the sample has the best performance in terms of microstructure, texture, and precipitations with the two-stage boiling water cooling normalizing process that the heating temperature is 1150 °C, and the normalizing intermediate temperature is 850 °C. With the above parameters, the microstructure is inhomogeneous along thickness. There are more {111}<112> textures, which are favorable to the growth of Goss texture. The proportion of high energy grain boundary reached 54.2%. The precipitates are significantly refined, which enhances the ability to inhibit primary recrystallization. The sub-surface thickness of the hot rolled plate increases from 40.6% to 62.1% with increasing Sn content from 0.01% to 0.11%. The degree of tin segregation at grain boundary increases with the increase of normalizing temperature and the decrease of medium soaking temperature.

Microstructure and mechanical properties of Mg−Gd−Y−Zn−Zr alloy plates with different initial textures after hot rolling

The effects of initial textures on the microstructures and mechanical properties of rolled Mg−4.7Gd− 3.4Y−1.2Zn−0.5Zr (wt.%) plates were studied by optical microscope (OM), scanning electron microscope (SEM), electron backscatter diffraction (EBSD), transmission electron microscope (TEM) and tensile test. In the plate with an initial texture of 〈0001〉//RD (rolling direction), relatively coarse grains and bimodal basal texture are developed. However, in the plate with an initial texture of 〈0001〉//TD (transverse direction), finer grain size and strong 〈0001〉//ND basal textures are obtained due to the higher degree of dynamic recrystallization during rolling. Additionally, the irregular-shaped long-period stacking ordered (LPSO) phases are elongated along RD in both plates, which results in anisotropic load-bearing strengthening behavior, and further leads to a certain degree of yield anisotropy. The analysis of the strengthening mechanism shows that grain boundary strengthening is the most effective strengthening method in the plates. Because of the finer grain size and the strengthening caused by the elongated irregular-shaped LPSO phases, the rolled plate with an initial 〈0001〉//TD texture achieves the highest yield strength along RD.

Interface enhancement mechanism of rolled Mg/Al clad plate with particle interface control

In this study, the cold-spraying process was utilized to deposit Al particles onto an Al slab, an Mg slab, and both Al and Mg slabs to form an ultra-thin interlayer, and then the clad slabs were rolled at 400 °C, developing three roll-bonding processes: the roll-bonding process with cold-sprayed Al powder on the Al slab (CS-Al), the roll-bonding process with cold-sprayed Al powder on the Mg slab (CS-Mg), and the roll-bonding process with cold-sprayed Al powder on both the Al slab and the Mg slab (CS-Both). The effects of three different cold-sprayed Al particle interlayer processes on the mechanical properties of rolled Mg/Al clad plates were investigated to improve the mechanical properties. The microstructure, texture evolution, intermetallic compound formation, mechanical properties, and mechanisms involved in the Mg/Al clad plate rolling were systematically investigated. The results showed that the pre-bonding between the particles and the substrates through cold-spraying had a significant impact on the bonding strength of the Mg/Al clad plates, and the CS-Both process can increase the average shear strength of the Mg/Al clad plates to 49.24 MPa at a medium reduction rate of 37.5 %, 2.5 times that of the conventional rolling process. The CS-Both process constructed more evident dual microscopic three-dimensional interfaces and promoted more thorough atomic diffusion at the interface through the double-sided cold-spraying process. Meanwhile, the dual cold-sprayed Al coatings on both the Mg slab and Al slab underwent dynamic recrystallization during rolling to form a homogeneous unit with no additional coating interfaces. Fine grain strengthening and dislocation strengthening were judged to be important mechanisms for improving the mechanical performance of the interfacial layer.

Quality Improvement of Health Plaster Products With Six Sigma Method and QCDSME Analysis

Health plasters are one of a pharmaceutical company's excellent items. There are still defective products in the manufacturing process, including torn paper, joint 1, not cut, perforated edges, joint 2, tucked, long-short, and asymmetrical. Research conducted between June and December 2021 reveals that 192.960 Kg of substandard items were discovered. The contribution of this research is to identify the underlying reasons of the problem and decrease the number of product faults. By using the QCDSME (Quality-Cost-Delivery-Safety-Morale) method analysis in the cost stage, this company is known to experience losses due to defective products of IDR 18,047,232 / year. The results of the analysis using the six sigma method at the analyze stage using the fishbone diagram tool are known that defective products are caused by the absence of size standards in the repair of plate and pressure roll positions, differences in operator responses, the absence of written procedures for handling product defects, and the existence of product roll rolls that are too loose or tight. The improvement proposal made next is to make a size standard for the plate position with a value of 12.5 ± 1 cm and a pressure roll with a value of 22 ± 1 mm with additional tools in the form of a ruler. After taking corrective steps and quality control on product defects, the results showed that the value of product defects decreased from the previous average of 1,119 pcs/day to 205 pcs/day, so that the company's loss value was reduced to IDR 3,306,240/year.

Using multiscale second phases to fabricate high-performance Mg-3Al-3Nd-0.1Mn alloys with bimodal grain structures

The quest for magnesium alloys that combine high strength and high ductility drives significant research effort aimed at broadening their use in various sectors. In this research, a low-alloy Mg-3Al-3Nd-0.1Mn (AEM330) was successfully prepared through Hard Plate Rolling (HPR), achieving an ideal combination of high strength and ductility via carefully modifying grain structure at lower rolling temperature. The optimized processing conditions led to an alloy with an ultimate tensile strength of 427 MPa and an notable elongation of 11.4 %. The AEM330 processed by HPR displayed unique bimodal grain structure with coarse grains (CGs) sizes ∼13.66 µm and fine grains (FGs) sizes ∼2.36 µm, and their strength and ductility were found to be directly related to the microstructural differences between CGs and FGs. A crucial discovery of this study is the essential role of the Al2Nd phase (larger than 1 µm) and the Al11Nd3 phase (smaller than 1 µm) in forming bimodal grain structure. The former phase plays a significant role in recrystallization by particle-stimulated nucleation (PSN), and the latter restricts grain size via Zener pinning. Furthermore, it was found that the ratio of CGs to FGs could be controlled by modifying the rolling temperature. Importantly, the simple composition and direct shaping process of the AEM330 alloy not only improve its cost-effectiveness but also streamline the manufacturing process; thus, enhancing its potential for broad industrial use.

Transverse difference of activation slip/twin system in wide AZ31 alloy plate during its rolling

The macroscopic finite element method (FEM) and the crystal plasticity finite element method (CPFEM) were combined to study the transverse difference of activation slip/twin system in wide AZ31 magnesium alloy plates during rolling. The macro-deformation and micro-texture evolution along the transverse direction of the plate during rolling were analyzed experimentally. The microscopic CPFEM was developed on the basis of the thermo-force coupling behavior during plate rolling obtained from macroscopic FEM. The CPFEM parameters were fitted by uniaxial compression experiments. This combination of two scale simulations accurately predicted the texture evolution during the rolling process and had been experimentally validated. Further examination of the deformation mechanism reveals that the transverse spread action of the plate is stronger at the edge region compared to center, and this transverse spread action has a more significant impact on the activation of the {10 1‾ 2} tension twin. The comparison of the activation and extension of pyramidal <a> slip in granular and plate-like grains reveals that plate-like grains are more prone to generate slip bands through the grain, leading to cracking of the grain along the slip activation band and further formation of sub-grains.

Quantitative characterization of Zr60700 alloy plate rolling in different directions based on electron back-scatter diffraction

Fully annealed Zr60700 alloy plates with a thickness of 15 mm were rolled at 15%, 30%, 45%, 60%, and 75% thickness reductions, and the rolling paths were unidirectional rolling (UR) and cross-rolling (CR), respectively. Electron back-scatter diffraction (EBSD) experiments revealed that the texture developed gradually towards the basal texture with increased thickness reduction. Severe orientation hardening enhanced the deformation resistance of the CR sample, resulting in a higher grain size than the UR sample. The plastic deformation during the rolling process was dominated by dislocation slip. The results of the prediction based on the Schmid factor (SF) and the calculation based on the in-grain misorientation axis (IGMA) showed that the prismatic <a> slip was the primary deformation mode in the early stages of the UR and CR processes. With the increase in thickness reduction, the basal <a> and pyramidal <c+a> slip played an increasingly important role. Compared with the UR process, the CR process was more accessible to activate the basal <a> slip and more conducive to forming the basal texture. Mechanical tests showed that the CR samples exhibited higher isotropy than the as-received and UR samples.

Research on the strengthening mechanism of Nb–Ti microalloyed ultra low carbon IF steel

Interstitial free (IF) steels are characterized by their interstitial free ferritic matrix due to addition of micro-alloying elements that draw carbon and nitrogen out of matrix to form carbonitrides. The IF steels typically have excellent deep drawing ability, certain mechanical strength, and high plastic deformation performance. In this paper, the microstructure evolution and carbides precipitation behavior during the hot rolling, cold rolling and annealing processes have been studied using both experimental and thermodynamic and kinetic modeling approaches. The strengthening mechanism of Nb–Ti microalloyed IF steel has been investigated. The results of the thermodynamic simulation indicates that the addition of Nb into Ti bearing IF steel promotes recrystallization at 900 °C, leading to fine recrystallized grains. Due to the recrystallization of austenite during the final rolling process, Nb–Ti microalloyed hot rolled plates exhibit finer grain size, fewer substructures, and lower dislocation density compared to the hot rolled plates containing only Ti. Building upon the initial fine and uniform structure, Nb–Ti microalloyed steel maintains a refined structure after undergoing cold rolling and annealing. The study of the carbides precipitation behavior suggests that TiN precipitates at high temperature above 1100 °C, while a substantial amount of (Nb,Ti)C and TiC precipitate at about 900 °C in Nb–Ti and Ti bearing steels, respectively. There is no significantly difference between the amount of carbides in steels hot deformed at 900 °C and in the hot rolled plates, indicating that the carbides mainly precipitate during the hot rolling process. There are negligible carbides precipitated during the coiling process at 600 °C. In Nb–Ti containing steel, Nb and Ti in solid solution are significantly reduced due to the large amount precipitation of (Nb,Ti)C during the final rolling process. The reduction of solid solution Nb effectively promotes the recrystallization of austenite. Therefore, the grains of hot-rolled, cold-rolled, and annealed strips are refined. In addition, there are more small size carbides in Nb–Ti bearing steel than that in Ti bearing steel. Therefore, the higher strength of Nb–Ti steel is mainly from the strengthening effect of grain refinement and carbides precipitation.