Rolling Process Research Articles

Efficient manufacture of TiNi/Ti2Ni intermetallic composites with a unique brick-and-mortar structure in a single hot rolling process

Efficient manufacture of TiNi/Ti2Ni intermetallic composites with a unique brick-and-mortar structure in a single hot rolling process

The influence of rolling process on fatigue properties of 316L/2Cr13 multilayered steel and analysis of its fracture process

The influence of rolling process on fatigue properties of 316L/2Cr13 multilayered steel and analysis of its fracture process

Research and design of the process of asymmetric cold rolling of steel strips. Message 1

Research and design of the process of asymmetric cold rolling of steel strips. Message 1

Intelligent Analysis and Optimization of Lubrication Status Factor Based on Dynamically Loaded Roll Gap in Cold Strip Rolling

Lubrication is a critical process in cold strip rolling, and the accurate characterization of lubrication characteristics is an essential factor affecting the strip quality. The roll bending and tilting roll in the flatness actuators change the loaded roll gap profile and affect the lubrication characteristics by flatness dynamic correction, thus the mismatch between the actual and setting values of the lubrication status factor. Firstly, the flatness deviation correction model of roll bending and tilting roll based on the key information of the rolling process is established according to the high-order flatness target. Secondly, the characterization of the instantaneous oil film thickness in the work zone based on the loaded roll gap profile is derived from Reynolds’ equation. Finally, the explicit characterization method of the lubrication status factor in the rolling force model of the final stand is established with the work roll bending, tilting roll, and instantaneous oil film thickness of the work zone as variables, relying on the UCM five-stand, six-roll tandem cold rolling mill. The statistical evaluation and application results show that the mentioned optimization method can improve the setting accuracy of the rolling force by about 60% and the after-rolling gauge accuracy by about 50%.

Effect of Minor Reinforcement with Ultrafine Industrial Microsilica Particles and T6 Heat Treatment on Mechanical Properties of Aluminum Matrix Composites

This study examines the use of ultrafine (~128 nm) microsilica (composed of a mixture of amorphous and microcrystalline silicon dioxide phases) particles, an industrial waste product, as a reinforcing material to create aluminum matrix composites (AMCs) via ultrasonic-assisted stir casting followed by T6 heat treatment. This study aimed to improve the mechanical properties of pure aluminum, which has insufficient strength for most engineering applications. The main objective of this study is to develop environmentally and economically efficient AMCs with improved properties, namely, the balance between strength and ductility, for further application in caliber rolling processes. Attention is also paid to minor reinforcements using a low concentration of microsilica (~0.36%wt), which minimizes the problems with the wettability of the reinforcing material particles. The composites reinforced with ultrafine microsilica exhibited enhanced mechanical performance, including a 59.7% increase in Vickers microhardness and a significant improvement in tensile strength, reaching 73 MPa. Additionally, T6 heat treatment synergistically improved ductility to 60.3% elongation while maintaining high strength, achieving a balanced performance suitable for forming processes. The study results confirm that using microsilica as a reinforcing material is an effective way to improve the performance of aluminum alloys, while minimizing costs and solving environmental problems.

A non-associated constitutive model based on yld2004-18p yield criterion and its applications on sheet metal forming analysis

For sheet metals, anisotropy is a significant property affecting sheet metal forming processes. The anisotropy of sheet metals is caused by the rolling process, and several anisotropic constitutive models have been proposed under the non-associated flow rule to describe the deformation and stress anisotropies of sheet metals independently. However, most of them are based on yield functions that are only identified by the experimental data of orthogonal axes, or yield functions that are applicable to only the plane stress state. In this study, the yld2004-18p yield function, which can be used to analyze the three-dimensional stress state in multiple axes with high accuracy and acceptable identification cost, is used to develop a non-associated constitutive model and subsequently applied to sheet metal forming analysis. Finite element analysis results of circular cup drawing and hole expansion demonstrate the capability of the yld2004-18p-based non-associated constitutive model in more accurately describing both the deformation and stress anisotropies of sheet metals.

Mechanical Properties and Strengthening Contributions of AISI 316 LN Austenitic Stainless Steel Grade

The main goal of this contribution is to evaluate the mechanical properties, strengthening contributions and microstructure development of austenitic stainless steel AISI 316 LN with high nitrogen content in the states characterized as the initial state and the states after rolling with different thickness deformations. The initial state was represented by solution annealing (777 K/60 min). The deformation state was characterized by rolling thickness reductions carried out at ambient temperature (TA = 295 K) with deformations in the range ε ∈ (0; 50> [%]. Studies of microstructures, mechanical properties and strengthening contributions before and after rolling were carried out. The initial state after solution annealing was as follows: offset yield strength Rp0.2 = 325 MPa, elongation A5 = 49% and diameter of grain size d =214 μm. The state after ambient rolling with thickness deformation ε = 50% was as follows: Rp0.2 = 994 MPa, A5 = 4% and d =64 μm. The maximum contribution to strengthening after rolling processing with 50% thickness deformation was dislocations (∆ R P0.2_DS =560 MPa) followed by twins (∆ R P0.2_DT =140 MPa).

Rolling torque of vibratory thru-feed rolling process for involute splined shaft

Rolling torque of vibratory thru-feed rolling process for involute splined shaft

A size-dependent closure criterion for slab corner defects during vertical rolling process based on mathematical method

A size-dependent closure criterion for slab corner defects during vertical rolling process based on mathematical method

Finite Element Simulation of Hot Rolling for Large-Scale AISI 430 Ferritic Stainless-Steel Slabs Using Industrial Rolling Schedules-Part 1: Set-Up, Optimization, and Validation of Numerical Model.

A growing need to reduce the environmental impact and cost of manufacturing stainless steels has led to the development of ferritic stainless steel as an alternative to austenitic and duplex steels. The development of new stainless steels involves the optimization of their hot rolling processes, with the aim of minimizing the occurrence of defects and improving productivity. In this context, numerical simulation using the finite element method (FEM) is presented as a key tool to reduce the time and cost associated with traditional trial-and-error optimization methods. Previous work oriented towards the simulation of stainless steels has been focused on the study of small samples, on the performance of laboratory-scale tests, and on the use of 2D FEM models. In this study, a three-dimensional FEM model is proposed to simulate the hot rolling process of large-scale AISI 430 ferritic stainless-steel slabs using an industrial rolling schedule employed in the actual manufacturing process of flat products. Model optimization is performed in order to reduce the computational cost of the simulations, based on the simulation of the first pass of the hot rolling process of AISI 430 stainless steel. The results show that model optimization reduces the computational time by 90.2% without compromising the accuracy of the results. Thus, it was found that the results for thickness and rolling load showed a good correlation with the experimental values. In addition, the simulations performed allowed for the analysis of the distribution of temperature and effective plastic strain.

Enhancement of Fracture Toughness of NiTi Alloy by Controlling Grain Size Gradient.

Fracture toughness is a critical indicator for the application of NiTi alloys in medical fields. We propose to enhance the fracture toughness of NiTi alloys by controlling the spatial grain size (GS) gradient. Utilizing rolling processes and heat treatment technology, three categories of NiTi alloys with distinct spatial GS distributions were fabricated and subsequently examined through multi-field synchronous fracture tests. It is found that the one with a locally ultra-high GS gradient (20 nm-3.4 μm) has significantly enhanced fracture toughness, which is as high as 412% of that of the normally distributed nano-grains with an average GS of 8 nm and 178% of that of the coarse-grains with an average GS of 100 nm. Theoretical analysis reveals that in such a gradient structure, phase transition in the coarse-grained matrix greatly absorbs the surface energy of subcritical and stable propagation. Meanwhile, the locally non-uniform GS distribution leads to deviation and tortuosity of the crack path, increasing the critical fracture stress. Furthermore, the nanocrystalline clusters distributed in the form of network nodes reduce the stress intensity factor due to their higher elastic modulus compared to the coarse-grained matrix. This work provides guidance for developing new gradient nanostructured NiTi alloys with high fracture toughness.

Effect of Intercritical Annealing on Microstructure and Toughness of Medium-Mn Steel with Elongated Prior-austenite Grains Formed via Two-step Hot Rolling Process

Effect of Intercritical Annealing on Microstructure and Toughness of Medium-Mn Steel with Elongated Prior-austenite Grains Formed via Two-step Hot Rolling Process

Effects of annealing temperature on the formability, mechanical and interface properties of laminated metal composite STS304L/Al1050/STS430

Laminated metallic composites (LMCs) produced by cold roll bonding generate high plastic deformation. After the rolling process, it is essential to promote a post-heat treatment (PHT) to increase adhesion, minimize hardening, and enhance the formability of LMCs. In this research, the effects of PHT at low temperatures (250, 350, and 450°C) on LMCs (STS304/Al1050/STS430) obtained by cold rolling were investigated. The Forming Limit Curve (FLC) and mechanical properties such as ultimate tensile strength (σ_UT), yield strength (σ_Y), elongation (ε), and the anisotropy index (r-value) of the LMC were evaluated. Results indicate the best PHT temperature that combines formability, increased adhesion between layers, and better mechanical properties, such as elongation (ε), which increases from 37% to 55%. At this PHT temperature, the brittle intermetallic layer was not detected, and the FLC showed the best performance. Furthermore, in industrial applications, this PHT condition allows energy savings compared to PHT conditions of high process times (>12 h) and/or temperature (>500°C) reported by several works in the literature.

Axial load of vibratory thru-feed rolling process for involute splined shaft

Axial load of vibratory thru-feed rolling process for involute splined shaft

Mechanical characteristics of roll crushing of ore materials based on discrete element method

The application of high-pressure grinding rolls (HPGR) for ore crushing is considered to be one of the effective ways to save energy and reduce emissions in the ore processing industry. The crushing effect is directly determined by the forces of ore material during roll crushing. However, the mechanical state of ore material in roll crushing and the effect of roll structure, process parameters, feed particle size, on the force during the crushing of ore material needs to be expanded. Therefore, this paper intends to use the discrete element method to study the mechanical characteristics of roll crushing of ore materials. Firstly, the iron ore breakage model parameters are calibrated according to compression and impact crushing tests. Then, considering different roll structures, process parameters, and feed particle sizes of high-pressure grinding rolls, a simulation of the industry high-pressure grinding roll crushing process is developed. The particle velocity is innovatively used to study the force of particles in different regions of the compression zone. Considering the force and wear of ore particles, rollers, and cheek plates, the breakage process of HPGR is analyzed comprehensively. The results show that the material in the roll-crushing process is mainly subject to the normal force. The forces on particles at different locations in the compression zone are related to average velocity. To improve the crushing effect of HPGR, the crushing process of the ore should be combined with the wear of the roller and cheek plates. The vulnerable zone between the roller and cheek plates is indicated, and the extrusion pressure of the roller is slightly lower than the shear force between the particles.

Modelling and industrial experiment on the dynamic deviation of rolling force during high precision rolling process

The dynamic deviation of rolling force during the rolling process is influenced by various coupling factors, including mill stiffness on the operating and driving sides, initial strip specifications, and roll crossing. These factors frequently lead to sickle bending of the strip and bearing wear. Although this dynamic deviation is crucial in the rolling process, the existing literature falls short in studying the mechanism of this deviation, both theoretically and experimentally. As a result, operators in industrial plants predominantly rely on experience to assess it and are unable to formulate specific adjustment plans. In this work, physical and mathematical models of rolling force deviation are developed to elucidate the underlying formation mechanism, taking into account the contact deformation of the roll system, plastic deformation of the strip and roll crossing models. Analysis of production data reveals that the dynamic deviation of rolling force exhibits three distinct fluctuation patterns: positive deviation, negative deviation, and alternating positive and negative deviation. Numerical simulations and industrial experiments are conducted to investigate the influencing factors and evolution rules of rolling force deviation under various rolling conditions. The results indicate that dynamic deviation increases with the growth of centreline deviation and wedge amount of strip, and exhibits a complex fluctuation pattern as the crossover angle increases. This is confirmed by both numerical simulations and experimental results. Based on these analytical results, several improvement methods have been implemented in industrial plants to reduce the dynamic deviation of rolling force. These include reducing stiffness deviation on both sides of the mill, narrowing the bearing housing clearance, and ensuring mill symmetry.

Rolling schedule design for the ESP rolling process based on NSGA-II-DE.

Multiple processes connected closely during the endless strip production (ESP) rolling, it is difficult to obtain the global optimal solution by multi-objective modelling of a single process, and the parameters to be optimized coupled with each other. To obtain the optimal solution, a multi-objective optimization model combining the power consumption, product quality, and loading balance was proposed for the design of an ESP rolling schedule. The thickness and heating temperature were simultaneously taken as the decision variables for coupling the temperature and loading in the rolling process, and the non-dominated sorting genetic algorithm-II (NSGA-II) based on differential evolution (NSGA-II-DE) was applied to obtain the Pareto solutions. To select an optimal solution, a satisfaction function was designed and applied to fully utilize the Pareto solutions. Furthermore, to prove the precision and efficiency of the method, the online schedule and that obtained by the NSGA-II method were compared. The results proved that the final selected solution had better quality and a more balanced loading force than the other two types, which could provide guidance for the actual production process.

Influence of different rolling processes on microstructure, texture and anisotropy of the Al–Cu–Li alloy

Influence of different rolling processes on microstructure, texture and anisotropy of the Al–Cu–Li alloy

Permanent Deformation of Thermoplastic Polyurethane in the Solid‐State Rolling Process

The findings suggest that rolling is a potentially effective technique for commercial applications in industries requiring high‐performance polymer films. The solid‐state rolling process is well‐established for semicrystalline and amorphous polymers, but its application to segmented, two‐phase polymers like thermoplastic polyurethane (TPU) which features physically cross‐linked systems and excellent physical and mechanical properties, remains underexplored. This study aims to investigate the rolling of TPU under various conditions to address viscous relaxation and achieve maximum thickness reduction, producing thin sheets. The rolling characteristics were assessed by measuring the thickness changes of rolled specimens of two TPUs with different hard phase fractions, alongside thermoset polyurethane (PUR) with chemical cross‐linking for comparative analysis. The results showed that the TPUs exhibited little plastic deformation at room temperature. The cold rolling test, conducted at a rolling speed of 0.5 m min−1 with a nominal reduction of 85%, indicated that the permanent reduction ratio was less than 35% for both TPUs. However, when the rolling speed was increased to 3 m min−1, the permanent reduction ratio increased to 67% and 60% for TPU ShA90 and TPU ShA85, respectively. This result indicates that at high rolling speeds, the thermal condition tends to change from isotherm to adiabatic in the rolling test. The maximum reduction ratio of 70% was achieved at a nominal reduction of 85% for TPU ShA90 at higher rolling temperatures and speeds.

The impact of Mn alloying and rolling processing on the microstructure and mechanical properties of LA141 alloy

The impact of Mn alloying and rolling processing on the microstructure and mechanical properties of LA141 alloy