Rolling Process Research Articles

Springback characteristics and influencing laws of four-axis flexible roll bending forming for aluminum alloy.

This study aims to solve the problem of springback control of aluminum alloy components in the rolling process, and the method of combining experiment and simulation is adopted. Firstly, a series of aluminum alloy samples are designed, and the four-axis flexible bending machine is used for precision roll bending. Secondly, the three-dimensional (3D) shape change data of the workpiece before and after roll bending is monitored and recorded in real-time by a high-precision 3D scanner. Meanwhile, aiming at different rolling process parameters of each group (including roll bend speed, feed rate, pre-deformation amount, mold curvature radius, and other factors), advanced finite element software is used to carry out detailed simulation and calculations. In addition, the coincidence is compared and analyzed between the actual experiment results and the simulation prediction. The stress-strain distribution and springback evolution of aluminum alloy during roll bending are described accurately. The experimental and simulation results show that the springback rate of aluminum alloy fluctuates in the range of 5% to 15% after four-axis flexible roll bending, and the specific springback value is influenced by various process parameters. For example, under the premise of keeping other conditions unchanged, when the roll bending speed is increased from 30mm/s to 60mm/s, the springback rate shows an upward trend of about 3%. By increasing the feed rate by 20%, an average decrease of about 7% in springback quantity is observed. It can be seen that the increase in roll bending speed can aggravate the springback phenomenon, and the appropriate increase in feed rate can play a certain role in restraining the springback. Further analysis shows that the choice of the mold curvature radius and pre-deformation amount also has a decisive influence on the springback characteristics. There is a nonlinear relationship between the two parameters and the amount of springback. Changing these two parameters in a specific range can effectively regulate the springback effect.

Choosing the Design of a Radial-Shear Rolling Mill for Obtaining a Screw Profile

The purpose of this work is a comparative analysis of the workpiece shape, and parameters of the stress-strain state during deformation on two radial-shear rolling mills with different roll configurations to determine the most suitable scheme for obtaining a screw reinforcement profile. During the FEM simulation of the radial-shear rolling process in the DEFORM program, a comparison of the workpiece shape change after rolling, equivalent strain, damage index, and Lode–Nadai index was carried out. Steel 10 (analogue of AISI 1010) was chosen as material workpiece. The analysis of the obtained data revealed that the most rational choice for the implementation of the reinforcement profile production process is the radial-shear rolling mill RSR 10-30. Subsequent modeling of the combined process of radial-shear rolling and twisting in a screw matrix showed that when using rolls of RSR 10-30 mill, the screw profile of the workpiece is formed successfully, whereas using rolls of the SVP-08 mill, the formation of a screw profile is impossible due to jamming due to an irregular cross-section shape. A laboratory experiment confirmed the possibility of forming a screw reinforcement profile at RSR 10-30 mill, and an assessment of the geometric parameters of the final workpiece showed full compliance with the dimensions of the profiles obtained during modeling and experiment.

Global knowledge flows and dynamics of scientists` priorities: from rolling process to labor protection in metallurgy

Global knowledge flows and dynamics of scientists` priorities: from rolling process to labor protection in metallurgy

A new deformation model for plane strain asymmetric sheet rolling process

A new deformation model for plane strain asymmetric sheet rolling process

Effect of hot rolling process on the microstructure and mechanical properties of a high-strength strip casting microalloyed steel

A novel Nb–V–Mo microalloyed steel with 1 GPa yield strength and high ductility was developed by strip casting. The effects of hot rolling on the microstructure and mechanical properties of the Nb–V–Mo microalloyed steel were investigated using scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, atom probe tomography and tensile tests. Both the as-cast and hot-rolled specimens exhibit a microstructure characterized by lath-like bainite and (Nb, V, Mo)C clusters, while the bainite lath was refined after hot rolling. Tensile test results show obvious improvements in the yield strength, tensile strength, and elongation of the hot-rolled specimen (1008 MPa, 1075 MPa, 20.1 %, respectively), compared to that of the as-cast ones (879 MPa, 978 MPa, 19.0 %, respectively). Additionally, the hot-rolled specimen displays a similar dislocation multiplication and storage capacity to the as-cast specimen, resulting in a comparable work-hardening capability during plastic deformation.

Enhancing strength-ductility synergy in low-Mn lightweight steel by large-deformed warm rolling and flash annealing

The presence of δ-ferrite makes it challenging to achieve higher strength-ductility in low-Mn lightweight steels. In this study, a large deformation warm rolling process was used to construct a precursor enriched with Mn, nano-precipitations, ultra-fine grains, and high-density dislocations. The subsequent flash annealing process not only promotes the formation of multi-heterogeneous structures but also refines and reduces δ-ferrite while increasing the ultrafine-grained hard phase martensite. Additionally, this process enhances the retention of retained austenite, whose ultrafine grains contribute to improved mechanical stability. The synergistic effect of multiple strengthening mechanisms enables low-Mn lightweight steel to achieve outstanding comprehensive mechanical properties, with a tensile strength of 1423 MPa and a total elongation of 23.0 %.

Visual study of hydrate particles agglomeration and rolling characteristic in gas-oil-water phase using a flow loop

Natural gas hydrate blockage always leads to safety problems in oil and gas transportation pipelines. It is important to look for the characteristic of hydrate blockage process. The hydrate blockage was visually investigated under gas-oil-water multi-phase flow conditions in a flow loop in this study. The change of pressure drop with water conversion rate variations were detected. The hydrate particle movements were also observed in the visual pipes at different liquid loadings and water cuts. It was found that the hydrate particles may agglomerate and deposit with an obvious rolling process in low water cut conditions. The oil phase will accelerate particles agglomeration in the contact interface of oil, gas and water, and form a large number of flocculent hydrates. A theoretical hydrate particle rolling model was conducted to analysis the experiment results, and the hydrate particle velocity increases first and then decreases with the increase of particle diameter due to the comprehensive influence of van der Waals force and drag force. The results also confirmed the maximum of the pressure drop increased when the liquid loading increased. However, the hydrate formation and blockage speed also slow down due to small component of the gas phase in high liquid loading. In addition, comparing with 20 % and 80 % water cut, 50 % water cut has the fastest hydrate formation speed in different experimental conditions. Furthermore, the maximum water conversion rate increased with have a higher water cut. More hydrate will form in the condition, which will lead to the decrease of flow velocity in the pipeline.

Enhanced mechanical performance and tailored degradation characteristics of rolled Zn-0.8Li-0.4Mn alloy

The application of biodegradable Zn-based vascular alloy stents proves to be an ideal solution for addressing cardiovascular diseases. In this work, a Zn-0.8Li-0.4Mn alloy is designed with no biological toxicity, and optimized microstructure and properties through a hot rolling process. The resulting alloy shows a combined enhancement in both mechanical strength and resistance to corrosion. Noteworthy is the effectiveness of rolling deformation in refining alloy grains, promoting the uniform distribution of precipitates, and enhancing strength and ductility. After 90 % deformation, the Zn-0.8Li-0.4Mn alloy demonstrates excellent mechanical properties, with peak yield strength and ultimate tensile strength of 406.0 MPa and 449.1 MPa, respectively, and elongation exceeding 75 %. Corrosion studies indicate a relationship between the degradation rate increase and grain refinement, with the primary corrosion mechanism being pitting corrosion. The corrosion product Li2CO3 exhibits high stability, providing a passivation effect on the alloy surface. This work establishes a theoretical foundation and practical reference for the development of new biodegradable Zn-based alloys tailored for biomedical applications.

EFFECTS OF HOT-ROLLING PROCESSES ON THE FRACTURE BEHAVIORS AND MECHANICAL PROPERTIES OF 2009Al/SiCp METAL MATRIX COMPOSITES

Defects such as pores and weak interfacial bonding in SiC-reinforced aluminum-matrix composites (AMCs) limit the reinforcement effect. The objective of this study is to control the microstructural defects and status of the Al/SiC interface in an 2009Al/SiCp composite using rolling processes. The influence of the rolling reduction rate on the microstructure and mechanical properties is investigated. The fracture behavior of the 2009Al/SiCp composite is observed through in-situ scanning-electron-microscopy tensile tests. The results demonstrate that an appropriate rolling reduction rate can effectively eliminate microstructural defects in the matrix and enhance the interfacial bonding strength of Al/SiC. Plastic deformation during the rolling processes expands the dislocation-strengthening regions near the Al/SiC interface. Consequently, mechanical loads can be more efficiently transferred from the aluminum matrices to SiC particles. In the as-sintered specimens, cracks primarily initiate at the Al/SiC interfaces during tensile tests. In contrast, cracks predominantly propagate from the SiC particles to Al matrices in the as-rolled specimens. This work provides a fundamental understanding of the dynamic changes in the microstructure and the resulting mechanical properties during hot rolling of SiC-reinforced AMCs.

Effect of intermediate annealing temperature and cold rolling deformation on the texture of yttrium bearing oriented silicon steel

The cold rolling and intermediate annealing process, along with the incorporation of rare earth elements, play an important role in the microstructure, texture, and inhibitors of oriented silicon steel. Currently, there is limited research on the impact of rare earth yttrium on texture evolution during the cold rolling and intermediate annealing processes. Therefore, the effects of different cold rolling deformations and intermediate annealing temperatures on the microstructure and texture of Y bearing oriented silicon steel have been studied. The experimental results demonstrate that the average grain size of the intermediate annealed plate progressively decreases with increasing the cold rolling deformation. This is because the high cold rolling deformation brings more additional dislocations and distortions, consequently enhancing the driving force for recrystallization. Observing the microstructure with various cold rolling deformation, the results show that the annealed plate with a 72 % reduction rate exhibited the highest Goss texture percentage of 4.83 %. This is because the cold-rolled sheet with a reduction rate of 72 % exhibits an abundance of Goss oriented substructures. These substructures quickly dominate the {111}<112> deformed matrix during the initial recrystallization, and promote grains nucleation and growth. As the annealing temperature increases, the driving force for the growth of recrystallized grains also increases, leading to a gradual increase in grain size. The plate annealed at 940 °C exhibits the highest percentage (4.83 %) of Goss texture. The addition of rare earth Y can lead to an increase in grain size in the intermediate annealed plate and facilitate the formation of {411}<148> texture. This is advantageous for the abnormal growth of Goss texture. The results demonstrate that a cold rolling deformation rate of 72 % and an intermediate annealing temperature of 940 °C are good for promoting abnormal growth of Goss orientation. The study results on precipitation kinetics suggests that the grain boundary nucleation of AlN and dislocation nucleation of MnS are the most effective way of nucleation. The precipitates in oriented silicon steel without Y are Al2O3 and MnS, while those in the samples with Y are AlN, YS, and YOxSy. The addition of rare earth Y leads to a reduction in both the density and size of precipitates. Moreover, With the increase of annealing temperature, the size of precipitates decreases and the amount of precipitates increases. Additionally, the addition of Y makes the steel more clean, meanwhile, the pinning effect of inclusions on grain boundaries is weakened. Therefore, the grain size of the steel with Y is larger.

Stability analysis of rolling mill system for flexible rolling process based on maximum Lyapunov exponent

Flexible rolling technology is the current development trend of strip production industry. However, due to the simultaneous change of mechanical, process and strip specification parameters in the flexible rolling process, the motion state of the system is difficult to analyze and stability control is hard to achieve. In this paper, the active motion characteristics of rolls in flexible rolling technology are considered, and the dynamic rolling process model is established to reflect the influence mechanism of process and specification parameters on the dynamic rolling force. The dynamic model of a 4-high rolling mill was developed and the structure-process-strip coupling strategy was applied to couple the models. The Runge-Kutta method was applied to solve the dynamic equation to obtain the maximum Lyapunov exponential spectrum for a single parameter variation. It is noteworthy that the two-parameter dynamics method was adopted to solve the dynamics on the two-parameter plane considering the nature of simultaneous variation of the system parameters, which solves the limitations of the traditional analytical method and is suitable for the application of the flexible rolling system. The results suggest that the parameters influence the motion state in the form of coupling, the influence pattern of each parameter on the stability is clarified, the evolution of the stable domain under the effect of parameter coupling is revealed, and the parameter matching strategy is determined. The results will provide a solution for the system parameter setting of flexible rolling technology and a theoretical reference for enhancing the stability of the rolling mill.

Extension of a Contact Subroutine for Composite Ring Rolling to Include Temperature Dependency

By combining the ring rolling and roll bonding processes, the product spectrum can be additionally expanded. Since a successful composite ring rolling process requires a higher growth tendency for the inner ring, previous publications commonly included a softer inner ring to reduce the flow resistance of the inner ring or specific geometries for rings and tools. In this work, the material combination of a 100Cr6 (DIN 1.3505, AISI 52100) outer ring and a 42CrMo4 (DIN 1.7225, AISI 4140) inner ring is used to show that the composite ring rolling process is also possible for material combinations with a balanced flow stress ratio and equal wall thicknesses. In earlier publications, the influence of temperature was neglected. As the influence on the yield stress and thus on the success of the process has a significant influence, this should be considered in order to be able to make a reliable statement. For this purpose, the bond formation of the two materials was investigated by bonding experiments, and an existing bond formation model was extended with respect to the temperature dependency. On the basis of this model, the process control parameters were investigated using FE simulations, and a ring rolling experiment was carried out.

Fabricating a pure titanium foil with excellent strength-ductility combination via bimodal grain structure coupling with deformation twins

Preparation of pure titanium foil by cold rolling deformation often confronts the strength-ductility trade-off dilemma, how to obtain an excellent strength-ductility combination remains a great challenge. In the present work, we have prepared a pure titanium foil with a bimodal grain (BG) structure consisting of coarse grain (CG) and ultrafine grain (UFG), coupling with high-density deformation twins (DT) via a cryogenic-temperature rolling (CTR) and partial recrystallization annealing (PRA) process. Notably, a high strength-ductility synergy with YS of ∼483 MPa, UTS of ∼517 MPa and elongation of ∼21 % is achieved. The high strength is mainly caused by pronounced fine grain strengthening from the UFG region and twin boundary strengthening from strong interactions between DT and dislocations activated in the CG region. The GND caused by the hetero-deformation between CG and UFG, along with the activation of pyramidal <c+a> dislocation via DT in the CG region endows the pure titanium foil with excellent ductility.

High-dimensional process monitoring under time-varying operating conditions via covariate-regulated principal component analysis

High-dimensional process monitoring, which aims to raise warnings for faulty events, is a fundamental tool in ensuring the safety of large-scale industrial systems. Over the last few decades, there has been significant interest in Principal Component Analysis (PCA)-based Statistical Process Control (SPC) charts. However, most of them rely on PCA’s optimal properties in homogeneous data, which often fails when dealing with heterogeneous data from industrial processes under time-varying operating conditions. To address this issue, this study proposes a Covariate-regulated PCA model (CrPCA) seamlessly integrated into a process monitoring framework. The main idea is to adjust the principal component directions smoothly according to the time-varying operating conditions, resulting in significantly less information loss in the principal component scores compared to existing methods. This approach further yields a low-dimensional feature vector that follows a distribution with fixed parameters, regardless of covariates, for real-time surveillance. We validate the performance of our methodology through a comprehensive numerical study and two real-world applications: wind turbine condition monitoring and hot rolling process monitoring.

Deep learning-based quality prediction for multi-stage sequential hot rolling processes in heavy rail manufacturing

Traditional quality control practices in heavy rail manufacturing primarily rely on experiential knowledge and numerical simulations. However, these methods come with significant drawbacks, including high costs, safety concerns, and limited accuracy due to the inadequate consideration of various influencing factors. Despite the accumulation of extensive data by some heavy rail manufacturers in recent years, achieving data-driven quality modeling remains a formidable challenge, mainly due to the complexity of the multi-stage sequential production process. This study presents the Temporal-Spatial Mapping approach to transform isochronous sampling data into spatially aligned data. Additionally, it introduces a multi-objective prediction model, Temporal-Fusion-LSTM (TFL), designed for evaluating the quality of heavy rails. The proposed model presents the Double-Layer LSTM with Time-Steps Fusion (DLL) architecture. The first layer of the DLL architecture targets the temporal transfer regularity within a single stage, while the second layer addresses the transition dynamics across multiple rolling stages in the heavy rail rolling process. Following this, the Local Process Correlation Matrix (LPCM) based on the Maximal Information Coefficient (MIC) is employed to empower the model to comprehend the intricate interactions among parameters in each stage of the rolling process. Finally, the Multi-Gate based Shared-Bottom architecture is employed to accentuate manufacturing processes highly correlated with the target quality indicators during multi-objective prediction. Real production data from a heavy rail factory is utilized to validate the effectiveness of the method. The experimental results unequivocally demonstrate that the proposed method accurately predicts heavy rail quality and facilitates cross-stage prediction, thus establishing the groundwork for data-driven quality diagnosis and pre-control in heavy rail production.

Optimization of mechanical, corrosion properties and cytotoxicity of biodegradable Zn-Mn alloys by synergy of high-pressure solidification and cold rolling process

Zinc (Zn) and Zn-based alloys are biodegradable materials, that have recently gained significant research attention due to their moderate degradation rate and good biocompatibility. However, their clinical applications are limited by their inferior mechanical properties. In this study, Zn-0.5Mn, Zn-1.0Mn, and Zn-1.5Mn (wt%) alloys were prepared via high-pressure solidification (HPS) and cold rolling (CR) procedures. Further, the microstructure, mechanical properties, corrosion behavior, and in-vitro cytotoxicity of these Zn-Mn alloys were systematically investigated. The results revealed that their yield strength (σys) and ultimate tensile strength (σUTS) enhanced significantly after synergy of HPS-CR treatment compared to CR alone. Notably, among these alloys, the Zn-1.5Mn alloy exhibited the highest σys and σUTS after HPS-CR, at 296.4±5.4 MPa and 322.6±3.5 MPa, respectively. The primary reason for this phenomenon is attributed to the combination of grain refinement and solid solution strengthening performance. Furthermore, these newly designed biodegradable Zn-Mn alloys exhibited appropriate in-vitro degradation rates and acceptable in vitro cytocompatibility when tested in Hanks' solution.

Effect of the Saccharin Concentration on Electrodeposition of the Fe-Ni Alloy

The FMM (Fine Metal Mask) used in the OLED display manufacturing process is a metal sheet with holes formed to allow the deposition of diode material only in the sub-pixel area. To prevent deformation and misalignment of the FMM (Fine Metal Mask) caused by heat during the RGB organic deposition process, an Invar plate with a thermal expansion coefficient (CTE) close to 0 is used. The Invar sheet applied to the current FMM is manufactured through a metallurgical process, and its final thickness after rolling is 20 micron. However, due to limitations in reducing thickness with the rolling process, for manufacturing FMM with a thickness of under 10 micron for next-generation high-resolution (UHD-level) displays, the bottom-up electroplating process is suitable. However, to maintain the shape of the electroplated Invar sheet while ensuring commercial-grade low CTE, heat treatment at temperatures exceeding 600℃ for an extended period is required, utilizing thermo-mechanical processing methods. If uniformity in the microstructure composed of nano-grains is ensured in the electroplated Invar alloy in the As-deposited, it is possible to increase the efficiency of the process by reducing the heat-treatment processing cost.Therefore, in this study, we investigated the microstructural evolution in the Invar alloy by controlling the surface stress of the electroplated layer during pre-plating. We controlled the key additive, saccharin, in the Fe-Ni alloy electrolyte to assist the diffusion of iron and nickel ions. By examining the relation between microstructural uniformity, determined by the plated layer, and CTE, we propose optimized process conditions for the pre-plated Invar sheet.

Effect of Strip Rolling and Wire Drawing Processes on NiTi Shape Memory Alloy Properties: A Comparative Study

Effect of Strip Rolling and Wire Drawing Processes on NiTi Shape Memory Alloy Properties: A Comparative Study

Development and validation of a fully coupled thermo-mechanical model for in-situ micro-rolling in laser-directed energy deposition: Single-track multi-layer case

Directed Energy Deposition (DED) has recently been hybridised with in-situ rolling, providing elevated temperature deformations and enhancing build quality. Analysing the thermo-mechanical aspects of deformations with sufficient fidelity can not be achieved experimentally. So, a fully coupled thermo-mechanical model for a multi-layer case using the finite element method has been developed to capture the thermal and mechanical facets of the deposition and rolling processes. Modelling features a hybrid active and quiet element activation strategy that mitigates convergence issues from activating a newly deposited layer over previously rolled ones. The model's predictions have been validated with reasonable accuracy against temperature history and rolling load measurements in an experimental case study using IN718. These predictions provide insights into the in-situ rolling effects with their quantification, including the impact on the thermal and stress-strain fields and histories. For instance, the temperature at the rolling location and the local temperature drop increase with the number of layers. The thermal stress induced by deposition overshadows the influence of in-situ rolling. The rolling deformation penetrates till the third preceding layer, and deposition leads to above the recrystallisation temperature reheating till the fourth layer. These predictions can be used for parametric optimisation with metallurgical criteria.

Study on precipitation in (CoCrFeMnNi)90Al6Ti4 high entropy alloy

(CoCrFeMnNi)90Al6Ti4 high entropy alloy (HEA) was prepared by adding Al and Ti elements into CoCrFeMnNi HEA. The alloy underwent processes including copper mold suction casting, 1473 K homogenization, 30 % cold rolling + 1273 K annealing + 1073 K aging, and water quenching and heating treatment. Microstructure and phase composition of both as-cast and heat-treated (CoCrFeMnNi)90Al6Ti4 HEA were studied using metallographic microscope, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and transmission electron microscope (TEM). The effect of heat treatment processes on the precipitation of second phases in (CoCrFeMnNi)90Al6Ti4 HEA was investigated, and mechanical properties of as-cast and heat-treated (CoCrFeMnNi)90Al6Ti4 HEA were studied via hardness tests. The results show that in as-cast (CoCrFeMnNi)90Al6Ti4 HEA, the second phase precipitated is primarily L21 structured AlTiNi2 phase. After homogenization, cold rolling, annealing, and aging processes, both the quantity and size of the second phase increase, with a small amount of nanoscale L12 phase appearing after aging treatment. With the progression of heat treatment, the hardness of (CoCrFeMnNi)90Al6Ti4 HEA increases, and mechanical properties are improved.