Rolling Of Ingots Research Articles

Numerical investigation of pull in control of rectangular AA1050 rolling ingot through the design of convex mould during direct chill casting process

The pull in effect/concavity on the lateral faces of the ingot is formed during the solidification of the ingot due to the thermal stresses induced in the ingot. A part of rolling ingots with pull in effect are cut by a conventional cutting process which affects the recovery and increases wastage and cost of production. In the present work, an elemental death and birth technique was used to develop a numerical model to study mechanical and thermal behavior during the solidification of AA1050 rolling ingot. The results of the model are validated with the results of the Williams model available in the literature. Furthermore, different mould designs provided with convexity on lateral surfaces with a convexity radius of 16 mm to 26 mm were numerically analyzed. A series of numerical simulations were conducted with varying mould convexity with an increment value of one. The results revealed that, providing convexity to the mould is an effective method to control the pull in effect during the direct chill casting process. The convexity radius of 26 mm is enough to completely eliminate the pull in radius of 23.34 mm for the rectangular AA1050 ingot.

Using the Radial Shear Rolling Method for Fast and Deep Processing Technology of a Steel Ingot Cast Structure.

In advancing special materials, seamless integration into existing production chains is paramount. Beyond creating improved alloy compositions, precision in processing methods is crucial to preserve desired properties without drawbacks. The synergy between alloy formulation and processing techniques is pivotal for maximizing the benefits of innovative materials. By focusing on advanced deep processing technology for small ingots of modified 12% Cr stainless steel, this paper delves into the transformation of cast ingot steel structures using radial shear rolling (RSR) processing. Through a series of nine passes, rolling ingots from a 32 mm to a 13 mm diameter with a total elongation factor of 6.02, a notable shift occurred. This single-operation process effectuated a substantial change in sample structure, transitioning from a coarse-grained cast structure (0.5-1.5 mm) to an equiaxed fine-grained structure with peripheral grain sizes of 1-4 μm and an elongated rolling texture in the axial part of the bar. The complete transformation of the initial cast dendritic structure validates the implementation of the RSR method for the deep processing of ingots.

Data Analysis of Production Data for Continuous Casting of Aluminum Rolling Ingots

Data Analysis of Production Data for Continuous Casting of Aluminum Rolling Ingots

Scientometric of topical directions increasing the efficiency for the process of rolling ingots and concast blooms from special steels prone to internal defect formation

Scientometric of topical directions increasing the efficiency for the process of rolling ingots and concast blooms from special steels prone to internal defect formation

Влияние термической обработки на свойства коррозионностойкой стали, легированной серебром и титаном

The field of application of corrosion-resistant austenitic steel is wide due to its resistance to corrosion and oxidation, durability, high strength and ductility. Austenitic corrosion-resistant steel is of particular importance for medicine. Medical instruments and products are made from it. However, the environment is very corrosive to metals and can lead to protein adsorption, biofilm formation (attachment of microorganisms/bacteria to the surface of the material), and corrosion or itself become a source of bacterial contamination. Recent studies have shown that the addition of Ag and Ti to corrosion-resistant steels can impart antibacterial properties to them without the need for surface modification. The article is devoted to the study of the structure and mechanical properties of a new antibacterial corrosion-resistant steel. The structure was studied by light optical microscopy and X-ray diffractometry. The mechanical properties were studied by stretching the samples on a tensile testing machine. The effect of homogenizing annealing and ingot rolling on the structure of corrosion-resistant steel is shown. According to the test results, it has been established that heat treatment of steel makes it possible to increase the ductility of steel. After rolling, the plates have a fine-grained structure. Normalization at 900 °C and 1000 °C relieves internal stresses and reduces the proportion of ferrite in the structure.

Effect of Grain Refiner on Fracture Toughness of 7050 Ingot and Plate.

In this paper, two types of grain refining alloys, Al-3Ti-0.15C and Al-5Ti-0.2B, were used to cast two types of 7050 rolling ingots. The effect of Al-3Ti-0.15C and Al-5Ti-0.2B grain refiners on fracture toughness in different directions for 7050 ingots after heat treatment and 7050-T7651 plates was investigated using optical electron microscopy (OEM) and scanning electron microscopy (SEM). Mechanical properties testing included both tensile and plane strain fracture toughness (KIC). The grain size was measured from the surface to the center of the 7050 ingots with two different grain refiners. The fracture surface was analyzed by SEM and energy dispersive spectrometer (EDS). The experiments showed the grain size from edge to center was reduced in 7050 ingots with both the TiC and TiB refiners, and the grain size was larger for ingots with the Al-3Ti-0.15C grain refiner at the same position. The tensile properties of 7050 ingots after heat treatment with Al-3Ti-0.15C grain refiner were 1–2 MPa lower than the ingot with the Al-5Ti-0.2B grain refiner. For the 7050-T7651 100 mm thick plate with the Al-3Ti-0.15C grain refiner, for the L direction, the tensile properties were lower by about 10~15 MPa; for the plate with the Al-3Ti-0.15C refiner than plate with Al-5Ti-0.2B refiner, for the LT direction, the tensile properties were lower by about 13–18 MPa; and for the ST direction, they were lower by about 8–10 MPa compared to that of Al-5Ti-0.2B refiner. The fracture toughness of the 7050-T7651 plate produced using the Al-3Ti-0.15C ingot was approximately 2–6 MPa · higher than the plate produced from the Al-5Ti-0.2B ingot. Fractography of the failed fracture toughness specimens revealed that the path of crack propagation of the 7050 ingot after heat treatment produced from the Al-3Ti-0.15C grain refiner was more tortuous than in the ingot produced from the Al-5Ti-0.2B, which resulted in higher fracture toughness.

Production of low-scandium Al – Mg alloys

The work was performed at the laboratory plant of semi-continuous casting of ingots (LPSCC) of the Institute of non-ferrous metals and materials science of SFU in order to obtain deformed semi-finished products with specified performance characteristics. The paper presents the results of obtaining an Al – Mg alloy doped with zirconium and scandium. Experimental rolling ingots were cast using casting modes that provide the structure parameters of the cast billet as close as possible to the parameters obtained in industrial conditions for ingots with a thickness of at least 300 mm. This paper presents the modes of two-stage diffusion annealing. The modes of hot and cold rolling of the experimental alloys obtained at the laboratory plant of semi-continuous casting of ingots are given. he paper presents the microstructure of the studied alloys in the cast and annealed state. The paper presents the results of research on the strength and plastic characteristics of deformed semi-finished products from experimental ingots of Al – Mg alloy with a scandium content of less than 0.1 %. The article presents comparative studies of six experimental alloys with an average content of the variable element Sc from 0.054% to 0.075%, respectively. The article shows that when the average concentration of Sc decreases to 0.054%, it is not possible to achieve the specified level of mechanical properties, due to the insufficient total concentration of the alloying element (Sc) in experimental alloys, which provides the effect of quench age hardening during the decomposition of solid solutions of scandium with the formation of intermetallic Al3Sc. It was shown that it is possible to reduce the concentration of scandium in the composition of Al–Mg alloys to 0.075% with the achievement of high performance characteristics: not lower than tensile strength — 390 MPa, proof strength — 275MPa, percentage of elongation — 12 %. The research was carried out within the framework of the State assignment by the laboratory of low-carbon metallurgy and power engineering of Siberian Federal University, as a participant company of REC «Yenisei Siberia» within the national project “Science and universities”.

ГОРЯЧАЯ ПРОКАТКА СЛИТКОВ, ИМЕЮЩИХ ФОРМУ ПРИЗМЫ С ОСНОВАНИЕМ В ВИДЕ РАВНОБЕДРЕННОЙ ТРАПЕЦИИ, КАК ПРОЦЕСС С КОМПЛЕКСНЫМ ЛОКАЛЬНЫМ НАГРУЖЕНИЕМ ОЧАГА ДЕФОРМАЦИИ

The classification of the processes of complex local loading of the deformation focus is considered. A description is given of the method of technological action on the deformation focus in order to create the most favorable scheme of operating stresses in it, a specific example of the technology under consideration is presented in the form of hot rolling of ingots with a vertical (normal to the axes of the rollers) axial section of alloys 29НК–ВИ and МНМц 38–2B.

Rolling of ingots of third-generation high-strength steels into sheets

One of the essential branches of today’s engineering production involves the production of sheet stock by rolling. In the automotive industry is used the majority of steel sheet stock. In recent decades, this sector has been striving to reduce vehicle emissions. One of the available solutions involves the use of advanced high-strength steels whose chemical composition and strengthening mechanisms make it possible to build the car body with thinner sheet blanks than before. For rolling trials in which ingots were converted into 1.8 mm sheet by combined hot and cold rolling were used two advanced high-strength steels containing 0.2 wt. % carbon and additions of manganese, silicon and different levels of aluminium. This procedure was found to produce strengths in excess of 1000 MPa combined elongation of more than 15 %.

Capability Process Assessment of Radial-Displacement Rolling of Heat-Resistant Alloy HN73MBTYU

The paper presents an experimental study on the technological capabilities of radial-displacement rolling of small diameter rods. These are made of heat-resistant alloy HN73MBTYU on pilot mills MISIS specifying the ingot rolling schedule with a diameter of 60 mm for a 22-mm-diameter rod. The following was conducted: a quality assessment of the rod obtained, as well as a compliance with the requirements of the current normative and technical documentation. The production possibility of small diameter rods of HN73MBTYU alloy from ingots with a 60-mm diameter that meets the technical documentation requirements, with the use of technology and radial displacement rolling mills, has been proved. The tested technological solutions have a high degree of readiness for industrial introduction in mini- and micro-metallurgical plant environment.

Improving the Aluminium Rolling Ingot Recovery using Tqm Technique

To improve productivity and profitability in Aluminium continuous casting industry the main action is to reduce losses due to defects resulting into revenue losses. Improving Rolling Ingot Recovery is possible by reducing the rejections & using the resources effectively (resources MAN, MACHINE, MATERIAL & CAPITAL) by applying TQM technique. This study presents a case about minimizing defects in aluminium continuous casting using Total Quality Management (TQM) techniques in which why-why analysis, Standard Operating Procedures (SOPs),and Cause and Effect analysis is used. It can be concluded from study that rejections, shell zone & inclusion can be reduced by, Continuous monitoring the health of the moulds, quality & quantity of water, the metal casting temperature, metal head in mould, water impingement angle, use of Ceramic foam filter plates, awareness & the adherence towards the guidelines.

Modeling and Investigation of the Process of Hot Rolling of Large-Sized Ingots from Aluminum Alloy of the Al-Mg System, Economically Alloyed by Scandium

Results of researches of process of hot rolling of ingots from the experimental aluminum alloy which is economically alloyed by scandium are given. The computer model of process of hot rolling with the use of which the straining, temperature and speed processing modes conditions is calculated and also power parameters of processing is calculated in applied to industrial conditions. It is shown that the use in the model of a certain shape of the ingot faces (Petrov's lock) and indirect rolling action in the edging stand is made it possible to reduce the likelihood of the formation and further development of micro cracks on the edges of rolled metal. The adequacy of results of modeling was confirmed by carrying out pilot-industrial tests when rolling large-size ingots from the experimental alloy and obtaining batches of hot-rolled plates and sheets of various sizes. The tensile test was used to study deformed samples after rolling and samples obtained on five regimes of heat treatment with varying heating temperatures of 300, 350 and 380 oС and holding time in the furnace for 1 and 3 hours. The results of the studies on samples of hot-rolled sheets 10 mm thick showed that, compared with the initial state, the strength characteristics of the metal after heat treatment are reduced by an average of 12-20%, and plastic characteristics increase by 50-65%. In this case, the heat treatment regimes 1 - 3 give a good ratio of the ductility and plastic properties of the metal.

Influence of Local Inhomogeneity of Thermomechanical Treatment Conditions on Microstructure Evolution in Aluminum Alloys

The influence of local inhomogeneity of the stress–strain condition on structure and texture evolution during thermomechanical treatment of aluminum alloys is studied in this work. For this purpose, laboratory rolling and plane strain tests that simulated roughing mill thermomechanical modes were performed. For all processes, the local inhomogeneity of structure evolution was estimated. For this purpose, x-ray texture analysis, EBSD and optical microscopy were used. Additionally, the calculations which allow to evaluate local inhomogeneity of stress–strain conditions for the each process were performed. The experimental results were compared with mathematical simulation output. They indicated structure and texture evolution inhomogeneities, especially during the plane strain and industrial rolling processes. In the plane strain test, typical local deformation zones occurred with different resulting grain size and texture effects than those observed in both rolling processes. This difference was mainly associated with different stress states, strain intensity and strain rate distribution throughout the deformation zone. This study demonstrated that the inhomogeneity of these parameters has a strong impact on structure and texture evolution in the first stage of thermomechanical treatment. In the center layer, laboratory rolling could adequately generate the structure and texture effects observed during rolling of ingots in a commercial mill. Plane strain tests can generate useful results only in the case of adequate choice of sample geometry.

Rheological Properties and Substantiation of Hot Rolling Regimes of Low- and Medium Carbon Structural Steels

In this paper the authors present the results of a study of plasticity and deformation resistance of the number of structural steels at temperatures of hot rolling. The patterns of changes in the studied characteristics of steels in the range of rolling temperatures are determined. In order to improve the quality of rolled products, we developed and substantiated recommendations for optimizing temperature of rolling ingot of the studied steels. The proposed recommendations have been verified by computer simulation of rolling high billets in flat rolls after heating up to 1100 and 1200 °C. For example, we showed the distribution of strains and stresses throughout the volume of the rolled product from steel grade 38KhS (State Standard GOST 4543-71).

Study on Deformation Penetration of Rolling Process by Rolling FEM Model of Wedged Ingot

In order to study the law of deformation penetration in thickness direction of the plate, 3D finite element model of wedged ingot rolling has been developed by means of software ABAQUS, in order to quantitative study the influence of reduction rate on the deformation penetration effect of steel plates, on the same reduction amount of whole wedged ingot and different reduction at different locations of the wedged ingot. Two pass rolling tests of small rolling mill on 120 mm thick wedged plate has been conducted. Finite element calculation and test results show that the center of plate almost no deformation when the reduction rate decreased to a certain extent ( < 15%) and the center of plate deformation rate increased significantly with the increase of the rate of pass reduction.

Controlled Solidification to Obtain Equilibrium Microstructure in DC Cast Rolling Ingot

In 6xxx Al alloys, most of the secondary constituent phases that are formed at the primary aluminum (α-Al) grain boundary or interdendritic region during direct chill casting are brittle “metastable” phases, which complicates the downstream processes of the cast ingot. To overcome this, the cast ingot is usually homogenized and heat-treated before hot rolling. In the current study, we have shown the possibility of casting 6xxx Al alloy ingot with near-equilibrium solidification structure, thereby eliminating the homogenization process. This in turn increases productivity by reducing downstream processing steps. Novel jet stirring and in situ homogenization techniques control the solidifying microstructure, and the microstructural evidences show that the cast ingot has equilibrium structures. The thermal history of the solidifying ingots is found to play a significant role in producing equilibrium microstructure. The setup of a modified DC casting process with a mechanism for the observed microstructure changes as compared to the standard process has been discussed.

Static recovery of an AlMg4.5Mn aluminium alloy during multi-pass hot-rolling

Abstract In multi-pass hot-rolling of aluminium alloys stored energy is created by the plastic deformation in the form of dislocations and sub-grains. The energy dissipates due to sub-grain growth and the annihilation or rearrangement of dislocations. Both mechanisms lead to a reduction of dislocation density and hence a decrease in yield stress, i.e. to recovery and softening. Reliable quantitative results on these aspects, experimental as well as theoretical, are of high technological importance. Literature provides many results on the hardening and softening behaviour of aluminium alloys during plastic deformation. Few quantitative investigations, however, deal with the static softening after hot deformation. In this contribution we share recent quantitative results on the static softening behaviour of an AlMg4.5Mn aluminium alloy and its implications for the industrial hot-rolling process. We show the static softening behaviour derived from stress relaxation tests on a Baehr DIL805 dilatometer. The results agree well with a microstructure model, which is based on thermally activated dislocation climb. The activation energy for static recovery, however, is found to be outside the range predicted by theory. The relaxation results together with additional thermomechanical characterization are used to calibrate a material model based on the Kocks-Mecking equation, which has been implemented in a commercial implicit Finite-Element software. Numerical results from a three-dimensional Finite-Element model of the industrial multi-pass hot-rolling process show how static recovery affects the distribution of dislocation density across the rolling ingot between passes.

Computational model for multi alloy casting of aluminum rolling ingots

Direct Chill (DC) casting is the primary route to produce rolling ingots in an industrial setup. During DC casting, the temperature field, fluid flow and solidification profile strongly depends on the ingot cooling practice. Further, the temperature field affects the macro/micro structure and defects which in turn determine the quality of the ingots produced. The present work focuses on the development of a steady-state computational fluid dynamics (CFD) model which appropriately treats heat transfer, fluid flow and solidification during multi alloy DC casting. This model is rigorously validated with experimental data from laboratory tests reported elsewhere. In multi-alloy co-casting, the simulation study is done to understand the effect of the casting speed and the metal distribution system. The present model is useful in providing an insight into the thermal-fluid flow and solidification profile that can help in identifying optimum process parameters.

Three-Dimensional Numerical Study of a Low Head Direct Chill Slab Caster for Aluminum Alloy AA5052

A 3D numerical study is carried out for a vertical direct chill (DC) rolling ingot caster for an aluminum alloy (AA-5052). The model incorporated the coupled turbulent melt flow and solidification aspects of the casting process. The caster consists of a low-head hot-top mold. The melt is assumed to have been delivered through the entire top cross section of the caster. The previously verified in-house computational fluid dynamics (CFD) code is used to investigate the effects of the important parameters such as casting speed, inlet melt superheat, and mold-metal contact effective heat transfer coefficient (HTC) on the low-head casting process. It is found that the sump depth (SD), liquid depth, and mushy thickness (MT) at the center of the ingot increase linearly with the casting speed while the shell thickness (ST) at the exit of the mold decreases linearly with the casting speed. Useful correlations concerning the above quantities with casting speed have been provided for the benefit of DC casting operators.

Low-head direct chill slab casting of aluminium alloy AA4045: 3-D coupled turbulent flow and heat transfer study

In the present study, a low-head direct chill (DC) industrial-scale caster for rolling ingots has been modelled using the advanced computational fluid dynamics approach. Specifically, the 3-D coupled turbulent melt flow and solidification heat transfer in a slab caster has been modelled for the aluminium AA4045 alloy. The turbulence generated in the melt pool is taken into account in the model through the implementation of a popular low-Reynolds (Re) number version of the k-ε eddy viscosity model. The solidification heat transfer for this complex opaque system has been considered through the employment of the well-known ‘enthalpy-porosity’ scheme. A staggered control-volume (CV)-based finite-difference scheme is used to discretise the governing transport equations and the associated boundary conditions. The discretised algebraic equations are then solved sequentially using the tridiagonal matrix algorithm with implicit under-relaxation factors. The SIMPLE algorithm was employed to resolve the velocity–pressure couplings in the momentum equations. Three important process parameters of this casting problem, namely, the casting speed, the pouring temperature (inlet melt superheat), and the convective heat transfer coefficient (HTC) at the metal–mould interface for the low-head 30-mm mould, are varied in their corresponding practical range of 60–180 mm min1, 16–64°C and 1000–4000 W m2°C, respectively. The predicted results are presented in the form of velocity and temperature fields, solid shell thickness at the mould exit, as well as the sump depth and mushy-region thickness at the centre of the ingot. The obtained results are then critically discussed.