Rolling Operation Research Articles

Microstructural Anisotropy, Mechanical Properties, and Fatigue Crack Growth Behavior of AA2050‐T84 Alloy

ABSTRACTThis study focuses on characterizing the microstructure and mechanical properties of AA2050‐T84 alloy produced in two different thicknesses, 20 and 130 mm. A comparative analysis between the two thicknesses aims to understand how the rolling operation for achieving thin plates influences the alloy's microstructure and overall mechanical performance. Microstructural analyses showed a highly anisotropic grain structure and preferred crystallographic orientation in the 20‐mm‐thick plate, causing anisotropic tensile properties. Also, a significant fatigue crack deviation was observed for the 20‐mm‐thick plate during fatigue crack growth tests due to its microstructure. This result was attributed to the microcrack formations perpendicular to the crack growth direction and slip bands at the intermediate ΔK, when the loading was parallel to the rolling direction. The findings from this study offer critical insights into how the rolling operation for achieving thin plates influences the microstructure and overall performance of the alloy.

Numerical simulation study on the cold thread rolling forming of Ti-6Al-4V alloy fasteners with external threads and their defects.

Abstract A three-dimensional numerical finite element model for cold rolling forming of external threads on Ti-6Al-4V alloy fasteners for aerospace applications was established using DEFORM-3D. This model was employed to investigate the characteristics of the cold rolling forming process and analyze the defects associated with the rolling operation. The stability of the ratio between torque and tangential load at the radius value of the rolling wheel (72.5) validates the accuracy of the model. The research results indicate that due to the unevenness of the extrusion force, the metal flow velocity is higher adjacent to the tooth-shaped surface compared to the central position. This causes the metal on both sides to accumulate and squeeze towards the middle position at the tooth top, ultimately resulting in tooth top folding defects.

Cu/Mo/NGs composites: Multilayer interconnected spatial net structure enhanced the mechanical properties

This study addresses the urgent problem of developing high-performance metal-based conductor materials capable of adapting to complex working environments. A novel method, called Accumulative Hot Pressing Roll Bonding (AHRB), is proposed for fabricating Cu/Mo/NGs multilayer composite materials. Through repetitive cold rolling and hot-pressing operations, nanoscale metal-based layered materials with thicknesses in the range of hundreds of nanometers are successfully obtained. This material features a multilayered interconnected net structure with Mo2C as the core and CuMo alloy as the framework. The layers are dislocated and connected to each other. The mechanical properties of the materials are significantly improved due to heterogeneous strengthening and grain refinement. The material achieves a tensile strength of 854 MPa, while the conductivity remains stable between 55% ∼ 60% IACS. The reaction between NGs and Mo leads to the formation of an Mo2C interface, while the hot-pressing operation promotes the formation of a CuMo diffusion interface. These two interfaces enhance the interlayer forces of the composites, thereby improving the material's integrity. The investigation of Cu/Mo/NGs multilayer composite materials presents a novel approach for alloying refractory metals Mo and Cu, offering promising prospects for future engineering applications.

Design of adsorption chillers under rolling conditions in naval applications: Experimental and numerical approaches

International shipping is one of the major contributors to the overall greenhouse gases emissions and therefore its decarbonization is a key priority worldwide. Among the possible energy efficiency measures, the use of waste heat for cooling through adsorption chillers has gained significant attention. However, the proper integration of such kind of chillers on board needs to consider the effect of the rolling movement of the ship. In the present work, two different sorption modules (i.e the couple of adsorber + evaporator/condenser) are experimentally tested in horizonal position and at different inclinations, considering permanent tilting or continuous moving. The results were subsequently used for the implementation in a dynamic simulation model and the design of the chiller for application on passengers’ vessels. Results showed that operation under constant inclination of 30° resulted in a reduction of the cooling energy supplied by 22.5 % for the module with zeolite and by 55.8 % for the module with silica gel. The highest specific cooling energy (SCE) is 0.26 kWh/kg for the zeolite module and 0.18 kWh/kg for the silica gel module. The main issues underlined under tilted operation is the progressive reduction of the water level in the evaporator, which causes incorrect operation of capillary-driven evaporation. Accordingly, the increase of water level in the evaporator was suggested as mitigation strategy. It was however found out that the issue is only relevant if prolonged operation in a tilted condition is foreseen, but not under typical rolling operation with continuous movement.

Stochastic optimization of solar-based distributed energy system: An error-based scenario with a day-ahead and real-time dynamic scheduling approach

Distributed energy systems (DES) have garnered global attention as a promising solution for the expansion of renewable energy sources. However, stochastic uncertainty in renewable sources poses significant challenges in the collaboration optimization of system design and operation. In this study, a comparison analysis was conducted to assess the effectiveness of the conventional distribution-based scenario generation (DS) method for stochastic optimization of a distributed energy system in residential buildings. The results revealed that the DS method inaccurately captured extreme scenarios and exhibited limitations in operation optimization, leading to significant performance evaluation bias. To address these challenges, a novel stochastic optimization approach was developed based on error-based scenarios and a day-ahead and real-time dynamic scheduling strategy (ES-DRS). This approach incorporated solar energy prediction errors to more accurately characterize extreme scenarios, while also considering dynamic dual-scale meteorological boundary condition for rolling operation optimization. Furthermore, the buffer storage and coverage periods in ES-DRS were investigated and discussed during dynamic scheduling. Results demonstrated that when the buffer storage and coverage period were set at 36.22 kWh in summer and 24 h, respectively, the DES with ES-DRS achieved optimal multi-objective performance. This resulted in an annual total cost of 3.21 × 104 USD and CO2 emission of 5.82 tons, representing reductions of 26.45% and 61.06%, respectively, compared to the conventional strategy. Overall, this research contributes to advancing uncertainty analysis and scenario-based optimization in DES, highlighting the potential benefits of adopting the ES-DRS approach to maximize overall performance from both economic and environmental perspectives.

Investigation on the Application of Worn Cutting Tool Inserts as Burnishing Tools

The amount of wear in cutting tools used in all machining processes is around 1 % to 2 % evaluation of the non-wearing areas of the inserts is economically beneficial. This study aims to test the usability of the non-wearing regions of the waste tungsten carbide (WC), cubic boron nitride (CBN) and ceramic inserts as a rolling tool in the deep rolling method and to observe their performance. The turned workpieces were deep rolled with three different types of waste-cutting tools (WC, CBN and ceramic) in different machining parameters (rolling force, number of passes, and feed rate). As a result, surface roughness and microhardness values obtained in deep rolling operations with these inserts were similar to those in deep rolling operations with other rolling tools. It has been determined that ceramic inserts perform better in deep rolling processes in terms of microhardness, and WC inserts perform better in terms of surface roughness. Thus, it has been determined that waste WC, CBN and ceramic inserts can be used in the deep rolling method.

Testing a new technique for producing artillery cartridge cases from pipe workpiece by roughing with a friction tool

The object of this study is the technological process of manufacturing parts such as artillery shells using pressure treatment methods. The work is aimed at solving the current scientific and technical task to improve the technological processes for manufacturing parts such as cartridge cases based on the use of a tangential rolling operation with a friction tool, which ensures the production of hollow products with a bottom. Using the finite element method, modeling of the bottom rolling processes was carried out, which made it possible to establish the effective geometry of the processed workpieces and their heating temperature. Recommendations have been devised for the design of new technological processes for roughing bottoms, which consist of determining the wall thickness of the workpiece before deformation, the heating temperature of the workpieces, and the amount of supply of the workpiece to the friction tool. The resulting recommendations were verified by experimental studies. Roughing of spherical bottoms should be carried out for pipes with a relative wall thickness (D/s) in the range of 15...20, the homologous heating temperature should be 0.8, and the relative feed of the workpiece into the friction tool should be 0.9. Testing the established relationships under laboratory conditions confirmed the recommendations for changing the shape of spherical bottoms during the roughing process. The results of metallographic studies on full-scale products confirm the results of the theoretical study. It is recommended to use this technique for products that have an axial hole (artillery shells, hydraulic cylinders, etc.), which will allow removing axial defects in the bottom after drilling the axial hole. The results could be used at machine-building enterprises in the manufacture of dual-use parts

Applications of genetic algorithm in prediction of the best achievable combination of hardness and tensile strength for graphene reinforced magnesium alloy (AZ61) matrix composite

Due to lack of knowledge about role of process variables in the hot rolling of magnesium alloy composites, the most desirable wrought products of magnesium alloy-based composites could not be successfully produced till date. Moreover, use of wrought graphene reinforced magnesium alloy-based composite has emerged as a lucrative option for developing novel light alloy products in structural applications. The implicative need to obtain the best possible properties of the composite dictates to fix the optimized process variables in rolling operation. The present study envisages the development of data driven model that enables to derive desirable properties of the said composite; so, in order to secure the optimized subset of requirements (process parameters), a metaheuristic optimization tool is employed. We invoke the use of Genetic Algorithm (GA) optimizing tool in association with linear regression, so as to achieve the best combination of hardness and tensile strength of AZ-61-graphene nanoplate (GNP) composite.Modified magnesium AZ-61 alloy composites of varying GNP content (0, 1 and 2 wt.%) are produced by stir casting. The cast composites are homogenized at 450 °C for 12 h, followed by iced water quenching. The quenched materials are subjected to hot rolling and the process variables of hot rolling operation consist of rolling temperature, number of rolling passes as well as the initial stock thickness. The rolled materials are tested for hardness and tensile strength as the response variables. Instead of using artificial neural network to fix the objective function of GA, a mathematical model is developed by regression analysis; the derived equation is used as the objective function for multi-objective optimization task. The present paper explores the usefulness of implementing evolutionary algorithm (as in genetic algorithm) to correctly forecast the effect of rolling process variables onto the hardness and tensile strength of the stir cast AZ alloy-GNP nanocomposite.The experimental results show that the maximum achievable hardness value happens to be 106.6 VHN and is very close to that predicted by GA, ∼107.41VHN. Similarly, the maximum experimental tensile strength is found to be 266.82 MPa whereas, the corresponding GA predicted value is seen to be 253 MPa. A close fit can thus be noticed between the GA predicted and the experimentally obtained values. Barring a couple of exceptions, the difference between the experimental and GA predicted data lies within 1 % to 5 % (based on [Experimental value ∼ predicted value]/ [experimental value]). This entices to believe that the adopted muti-objective optimization strategy is quite useful in determining the optimum combination of rolling parameters that aids in achieving the most desirable property combination.

Novel Approach to Address Brownish Edge Band in Low Alloy Cold Rolled Steel Used in Tin Plate

Thin film formation of lubricant plays a key role in supporting lubrication and abating wear. During cold rolling of steel, esters, or film formers in rolling oil play an important role in the mixed lubrication regime. The property of the lubricant holds the key to achieving the mean film thickness during the mixed lubrication regimen. Band formation in cold rolling is often related to inadequate acid pickling. During cold rolling operation, the film formation between asperities plays an important role in controlling friction and coil temperatures. A well formulated lubricant ensures smooth transition of lubrication throughout the range of roll bite temperature and also across the lubrication regimes. A sudden spike in coefficient of friction (CoF) can often lead to increased wear and abnormal increase in coil temperatures resulting in band formation. The study highlights degradation of oil sample leading to the problem and the role of key lubricant properties in esters in mitigating the problem.

Investigation on thread rolling processes of screws for intelligent thread rolling system

The traditional screw production equipment is very large, and many procedures need manual operation, which has a certain influence on the production of screws. In order to improvement the production efficiency, a new type of “Intelligent Thread Rolling System” is to be designed for the requirement. In this system, it is necessary to provide and transmit the relevant data for screw manufacturing, especially in the process of thread rolling. The thread plate design changes the traditional flat shape to become the curved shape. This paper has used the numerical model of the finite element method to calculate and simulate thread rolling process of thread plate of curved shape to understand the applicability. The results of relevant parameters on the thread rolling are obtained to compare with experimental data of Intelligent Thread Rolling System. Under certain test condition, the screw embryonal material can produce threads and cut off tails, but the created thread shape and depth are non-standard. The results are consistent with experimental data. The main reason is that the thread surface of thread plates of curved shape has not been redesigned. Due to the comparison and verification, the numerical parameters can be provided for the actual thread rolling operation of the ITRS. This is very helpful for the completion of the ITRS development.

Effect of silver and heat treatment on properties of 03Kh17N10M2 austenitic steel wire

The article examines the influence of various heat treatments, their temperature, as well as silver alloying on mechanical properties, phase composition and structure of steel wire from chromium-nickel-molybdenum austenitic stainless steel 03Kh17N10M2. Choice of the amount of silver alloying was based on previous studies of the antibacterial effect of modifying medical steels with silver. Since the antibacterial effect was confirmed on several bacterial strains, for the most efficient operation of alloys, it is necessary to determine the best temperature mode for working with them. Steel for the study was smelted and then transformed into wire through rolling, forging and drawing operations. On the obtained wire samples of different diameters with a silver content (0; 0.2 and 0.5 wt. %) mechanical tests were carried out to determine the elongation, yield strength and tensile strength. Various modes and temperatures of heat treatment were tested on wire of different diameters to study their effect on mechanical properties and structure. Microstructure of the wire samples subjected to heat treatment and obtained after drawing was investigated. A phase analysis was also carried out to determine the effect of silver in various quantities on austenitic steel. According to the results of the phase composition analysis, it was concluded that silver reduces the amount of gamma phase in steel, and this effect increases in proportion to the increase in silver amount. This change correlates with a slight drop in the metal ductility. At the same time, there are no significant changes in the strength characteristics and microstructure from the presence of silver.

Experimental investigation on slip conditions during thread rolling with flat dies

The process design of flat die rolling operations can be a tedious and costly process due to the challenges posed by small process windows. Within this work, an effort is made to closely investigate and understand the process limits caused by excessive slippage of the workpiece. Optical measurements are carried out to capture the characteristics of excessive slippage and the influence of the stroke rate and the tribological system on this process limit. Large differences in slippage were observed, depending on the tribological system. While systems with polymer based lubricants showed excessive slippage at low stroke rates, systems using oil or no lubricant endured higher stroke rates before process limits were reached. The optical measurements revealed three major forms of slippage: successful rolling without slippage, failure due to excessive slippage at process start, and failure due to excessive slippage at around one workpiece rotation.

Investigating the impact of roller position on pressure tube-end fitting rolled joint performance using 3D explicit finite element analysis

Pressurized Heavy Water Reactors (PHWRs) utilize Zr-2.5 Nb pressure tubes that are connected to SS-403 end fittings through rolled joints. These rolled joints are made using a rolling tool equipped with five rollers and a tapered mandrel. The action of the rollers induces plastic deformation on the inner surface of the tube. The tapered mandrel promotes rotation and axial advancement of the rollers into the pressure tube through friction. However, prolonged usage of this rolling tool can lead to the wearing down of both the mandrel and the rollers. Consequently, this wear and tear can cause the rollers to deviate from their intended position within the rolled joint. Such misalignment can lead to excessive rolling of the pressure tube into the entry taper section of the end fitting. This, in turn, generates higher residual stresses than initially anticipated. This issue may also arise from accumulated tolerances within the rolling tool or positioning errors made by operators during the rolling operation. The overextension of the rollers can significantly increase tensile residual stresses within the pressure tube, and management of these stresses is critical to prevent failure of the pressure tube due to Delayed Hydrogen Cracking.The primary objective of the present investigation is to explore the effects of the overextension of rollers on the residual tensile stresses in the transition region of the rolled joint. This objective is achieved by employing a three-dimensional explicit finite element analysis methodology. In order to ensure the reliability and authenticity of the finite element model, the computational results are cross-validated with the experimental findings documented in the existing literature. The current investigation involves the examination of two distinct configurations of pressure tube to end fitting rolled joints, which are typically found in PHWRs. The results of the present inquiry reveal an optimal roller position that minimizes residual tensile stresses within the transition region of a rolled joint. Furthermore, it is observed that any deviations in the roller position within a range of 5 mm, beyond the optimal position, result in a negligible increase in residual tensile stress.

Amount of damaged starch in laboratory and production grinding flour

Due to the different approach to the Russian and European flour milling process in Russia, the amount of damaged starch (SC) at flour mills is rarely controlled. This issue needs a comprehensive study, since the indicator of damaged starch is of great importance: its assessment allows determining the intended purpose of flour (bread baking, confectionery and pasta production). Manage the flour-grinding process in terms of monitoring the operation of the mill rolls during grinding, namely, checking their parallelism and wear, optimizing the gap and pressure. Flour with a high content of damaged starch should not be used for the same purpose as flour with a low content of damaged starch. Also, the assessment of the damaged starch index allows improving the dough yield by selecting the optimal water absorption coefficient (water absorption), optimizing the volume, color and shelf life of the finished flour products. At the initial stage, the purpose of the study was to identify the relationship between the amount of damaged starch and flour quality indicators, as well as the rheological properties of dough from laboratory flour and industrial grinding, and to further clarify the level of damaged starch on a large number of samples of flour of different quality according to its intended purpose. The available literature data on this issue are contradictory. The amount of damaged starch in flour was determined on a damaged starch analyzer. The following were also determined: the quantity and quality of gluten, the falling number, dough stability, liquefaction, water absorption of 20 samples of wheat flour of laboratory and industrial grinding. The results of the study showed that the amount of damaged starch in industrial milled flour was higher, and amounted to 20-27 UCD (average 24 UCD) versus 15-21 (average 18 UCD) in laboratory milled flour. A correlation was found only in industrial milling flour between damaged starch and the falling number (0.632), liquefaction (0.781) and water absorption (0.690). In industrial flour, with an increase in the amount of damaged starch, there was an increase in water absorption and liquefaction of the dough, which is consistent with the literature data; there was no clear decrease in dough stability. In the flour of laboratory grinding, the dependences between the indicators are insignificant.

Application of Artificial Intelligence for Automated Defect Detection on Nuclear Power Plant Fuel Asssembly Components

For manufacturing nuclear fuel, Framatome's various plants and workshops carry out rolling operations of chemical and thermal treatment on zirconium tubes. After the finishing stages of these tubes, a series of checks are carried out, including a visual inspection of the final external surface, to ensure the quality and integrity of these cladding tubes, essential for nuclear safety. Today, this visual inspection is automated but requires a significant amount of time for an expert to review the rejected components by the current analysis system. To minimize the number of components rejected by the existing system while respecting the same level of defect detections, a study of the application of Artificial Intelligence was conducted. Two convolutional networks of a similar architecture have been developed: one for making a decision to sanction the tube and one to classify the type of rejection. In this article we present the architecture of the chosen neural networks, as well as the performance obtained for a large set of evaluation data from the rejections of produced tubes. Finally, we put these results into perspective by exposing the potential productivity gain using this system in production assisted by Artificial Intelligence.

A Truncated Transient Slab Model for a Reheating Furnace

This paper considers the steel reheating process, in which cold slabs are reheated to a temperature suitable for hot rolling operations. Temperature uniformity within the slab is very important during reheating, as non-uniformities often lead to quality concerns in the later stages of the production process. Attaining slab temperature uniformity is quite challenging, therefore, a thorough understanding of the reheating process becomes very important. Due to the extreme conditions inside the furnace, numerical tools like computational fluid dynamics are necessary for such situations. However, when applied to these complex installations, it often leads to very lengthy computational times. This paper develops a computationally efficient transient model to simulate the environment around a slab. This Truncated Transient Slab Model is a coupled model: it uses the temperature and flow profiles from a full-scale steady-state simulation and imposes those on a smaller domain that represents the immediate environment around the slab. The efficiency of the model is compared to the state of the art. With the simulations available in the literature, it was found that the proposed model can simulate a furnace seven times larger (grid size), with much higher grid and time resolutions, using only a third of the computational resources.

The Hot Strip Mill Scheduling Problem With Uncertainty: Robust Optimization Models and Solution Approaches.

In this article, we focus on a biobjective hot strip mill (HSM) scheduling problem arising in the steel industry. Besides the conventional objective regarding penalty costs, we have also considered minimizing the total starting times of rolling operations in order to reduce the energy consumption for slab reheating. The problem is complicated by the inevitable uncertainty in rolling processing times, which means deterministic scheduling models will be ineffective. To obtain robust production schedules with satisfactory performance under all possible conditions, we apply the robust optimization (RO) approach to model and solve the scheduling problem. First, an RO model and an equivalent mixed-integer linear programming model are constructed to describe the HSM scheduling problem with uncertainty. Then, we devise an improved Benders' decomposition algorithm to solve the RO model and obtain exactly optimal solutions. Next, for coping with large-sized instances, a multiobjective particle swarm optimization algorithm with an embedded local search strategy is proposed to handle the biobjective scheduling problem and find the set of Pareto-optimal solutions. Finally, we conduct extensive computational tests to verify the proposed algorithms. Results show that the exact algorithm is effective for relatively small instances and the metaheuristic algorithm can achieve satisfactory solution quality for both small- and large-sized instances of the problem.

Understanding the mechanisms behind the development of cube orientation in the non-cube grains during plane strain compression of medium to high stacking-fault energy FCC metals

Medium to high stacking-fault energy FCC metals develop a pronounced cube texture during static recrystallization. Previous studies reported that the recrystallized grains can nucleate from the cube-oriented regions developed in the non-cube grains during plane strain compression. However, the mechanisms behind the development of cube orientation in the non-cube grains are still unknown. In this work, we used an elasto-viscoplastic fast Fourier transform (EVP-FFT) based crystal plasticity model to study the lattice rotation of non-cube orientations under plane strain compression. Firstly, we focus on a non-cube grain which developed the cube orientation in previous experimental work. The non-cube orientation does not rotate towards the cube orientation during single material point deformation under ideal plane strain compression. In contrast, the same non-cube orientation develops cube-oriented fragments during the polycrystalline deformation. Analysis of the micro-mechanical fields reveal that the local deviation of the RD-ND shear component leads to a remarkable change in the slip system activity which promotes the lattice rotation towards the cube orientation. Although the mechanism remains unchanged, the location and volume fraction of the cube orientation developed in the non-cube grain vary significantly in different grain neighborhoods. For the general case of a polycrystalline microstructure, deviation of the RD-ND shear component shows the highest correlation with the development of the cube orientation in the non-cube grains. The deviation is larger for the non-cube grains with higher Taylor factor. These findings have significant implications for the cube texture control during the practical rolling operation and recrystallization.

Strategies for constructing mathematical models of nonlinear systems based on multiple linear regression models

Abstract Mathematical systems often have nonlinear, time-varying, time-lagged, and uncertain factors, which affect the experimental prediction accuracy. In order to improve the experimental prediction accuracy, this paper inputs the independent and dependent variable data sets as the original samples into a multiple linear regression function performs fitting calculations to obtain the nonlinear factors, and constructs a mathematical model of nonlinear systems based on a multiple linear regression model. In this model, the expected output value is calculated, and the input vector and output vector are continuously controlled for rolling operations to obtain the prediction results. A mathematical experiment of nonlinear system dynamics of vibration of deep water trap-test pipe system is set up to test the prediction ability of the model. The results show that the nonlinear system mathematical model based on the multiple linear regression model has a very high prediction accuracy. In the mathematical experiments of vibration nonlinear system dynamics of deep water trap-test pipe system, the error of the nonlinear system mathematical model based on multiple linear regression model in the transverse flow vibration frequency of the trap pipe column is 2%, which is lower than the single trap pipe calculation model by 4%. The prediction accuracy of the nonlinear system mathematical model based on the multiple linear regression model is higher than that of the single test tube model calculation by 78%. This shows that the nonlinear system mathematical model based on the multiple linear regression model can improve the experimental prediction accuracy.

Generic and broadband non-linear time domain impedance boundary condition

An approach for modeling time-domain impedance boundary conditions (TDIBC) is presented. Its implementation in numerical codes relies on the inverse Fourier transform to recast the convolution problem into an array rolling operation. The proposed approach offers several advantages, including an inherently broadband formulation that can handle discontinuous waves, the ability to cater for any impedance law on frequency, ease of extension to non-linear impedance operators, and the elimination of ad-hoc, previously-tuned parameters. The linear solver, whose code is shared, is first validated against theoretical results. The non-linear solver is then validated against experimental data obtained in an impedance tube setting. Finally, a fully non-linear Navier–Stokes solver based on discontinuous spectral differences is utilized to demonstrate the implementation of the TDIBC in a grazing incidence duct configuration.