Radial-shear Rolling Research Articles

Experimental testing of radial-shear rolling to obtain a deformed alloy of the Co – Cr – Mo system

Experimental testing of radial-shear rolling to obtain a deformed alloy of the Co – Cr – Mo system

Study of changes in the structure of zirconium alloy E125 after deformation by radial shear rolling

The rheological properties of the alloy E125 (Zr‑2.5 %Nb) were studied in the range of deformation rates 0.5–15 s‑1 and the temperature range 20–770 °C. A database for computer FEM modeling was created in the specified temperature and speed ranges. In the DEFORM‑3D software package, numerical simulation of a complex radial shear rolling process was carried out using the obtained database. The conditions conducive to the grinding of the alloy structure into an ultrafine‑grained state were determined. Based on the simulation results, a full‑scale experiment of rolling a bar made of alloy E125 on a radial shear rolling mill RSP‑14/40 in 7 passes from a diameter of 37 mm to 20 mm with a total compression in diameter of ε = 85 % was carried out. At the same time, according to the modeling, the total accumulated deformation in the most developed peripheral zone was 27,5 mm/mm. Due to the complex vortex flow of the metal, the distribution of accumulated deformation over the cross section was uneven with a gradient to the axial zone. This should also affect the change in the structure. The changes and the gradient of the structure were studied by the method of EBSD mapping of the sample section with a resolution of 2 mm. The microhardness gradient of the cross section was also investigated by the HV method. The axial and central zones of the sample were studied on the. The structure has a pronounced gradient from the formed equiaxed ultrafine‑grained (UMZ) structure on several outer millimeters of the peripheral section to an elongated rolling texture in the center of the rod. The work shows the possibility of processing with the formation of a gradient structure with enhanced properties for the E125 alloy, and also presents a database for FEM calculations.

Numerical simulation of workpiece temperature field during radial shear rolling of biomedical Co-Cr-Mo alloy

This paper describes the analysis of temperature field of workpiece during radial shear rolling (RSR) of biomedical Co-28Cr-6Mo alloy. In the process of hot metal forming, the temperature distribution in the deformation zone has a significant influence on the quality and properties of the final product. In some cases, the deformation within a narrow temperature range is required to provide the desired properties. To obtain data on change in temperature, the computer simulation of RSR was carried out using finite element method. According to simulation results, the temperature distribution of bar depending on the variable process parameters such as temperature of workpiece, rotary velocity of rolls, elongation ratio, diameter of workpiece, and temperature of tool was evaluated. It was determined that the most significant parameters influencing on the distribution of the temperature field are the workpiece heating temperature and the rolling speed. The RSR process makes it possible to effectively manage the distribution of temperature field due to selecting technological parameters and, thereby, control the formation of the alloy structure. The data obtained can be useful for developing the modes of RSR of Co–Cr–Mo alloy.

Structure and strength of Al-Mn-Cu-Zr-Cr-Fe ALTEC alloy after radial-shear rolling

The phase composition and structure of as-cast and deformed Al-1.53Cu-1.66Mn-0.38Zr-0.15Cr-0.15Fe (wt.%) were investigated. The radial shear rolling was used for the deformation of the alloy. The structure of as-cast alloy consists of aluminum solid solution, eutectic Al6(FeMn) and Al2Cu, as well as Al7Cr and Al20Cu2Mn3 dispersive particles. It is assumed that radial shear rolling results in the refinement and partial dissolution of Al20Cu2Mn3 dispersoids. Along with this, significant grain refinement was established after deformation. The average grain-subgrain size in the alloy after deformation is 1.6 μm. After deformation the alloy has the yield stress of 83 MPa and ultimate strength of 216 MPa. The elongation to failure of the deformed alloy is 25 %. Owing to the partial deformation induced dissolution of the aluminides and supersaturated solid solution formation, there is a potential for strengthening upon heat treatment of the alloy and improvement of its thermal resistance.

The Effect of Radial-Shear Rolling Deformation Processing on the Structure and Properties of Zr-2.5Nb Alloy.

The rheological properties of the Zr-2.5Nb alloy by the strain rate range of 0.5-15 s-1 and by the temperature range of 20-770 °C was studied. The dilatometric method for phase states temperature ranges was experimentally determined. A material properties database for computer FEM simulation regards the indicated temperature-velocity ranges were created. Using this database and DEFORM-3D FEM-softpack, the radial shear rolling complex process numerical simulation was carried out. The contributed conditions for the ultrafine-grained state alloy structure refinement were determined. Based on the simulation results, a full-scale experiment of Zr-2.5Nb rod rolling a on a radial-shear rolling mill RSP-14/40 was carried out. It takes in seven passes from a diameter of 37-20 mm with a total diameter reduction ε = 85%. According to this case simulation data, the total equivalent strain in the most processed peripheral zone 27.5 mm/mm was reached. Due to the complex vortex metal flow, the equivalent strain over the section distribution was uneven with a gradient reducing towards the axial zone. This fact should have a deep effect on the structure change. Changes and structure gradient by sample section EBSD mapping with 2 mm resolution were studied. The microhardness section gradient by the HV 0.5 method was also studied. The axial and central zones of the sample by the TEM method were studied. The rod section structure has an expressed gradient from the formed equiaxed ultrafine-grained (UFG) structure on a few outer millimeters of the peripheral section to the elongated rolling texture in the center of the bar. The work shows the possibility of processing with the gradient structure obtaining and enhanced properties for the Zr-2.5Nb alloy, and a database for this alloy FEM numerical simulations are also presents.

Effect of radial-shear rolling on particle’s morphology and mechanical properties of AA7075 alloy

Effect of radial shear rolling on the morphology of intermetallic particles, and the mechanical properties of 7075 alloy at different processing temperatures and heat treatment after deformation was investigated. The results were consistent with data on metallographic investigation of phase particle shape, counts, and distribution. It was found that the formation, quantitative distribution, and circularity of particles at the surface and in the centre of the bar depended on the processing temperature and temperature gradient between surface and centre and were defined with a scheme of stresses in the deformation zone. The values of strength properties for all bars obtained by RSR depended on the processing regimes, while plasticity (elongation to failure δ = 14%–20%) increased with the growth of processing temperature. Article highlights Radial shear rolling makes it possible to obtain aluminium alloy bars with a gradient structure and a combination of high strength and ductility. The influence of the RSR method is reflected in the nature of the distribution of dispersive particles in the matrix of alloy. Mechanical properties of bars subjected to the RSR method depend on the initial processing regimes, while the level of plasticity increases with the growth of processing temperature.

Kazakhstan Study of the influence of large shear deformations and vortex flow of metal on the formation of an equiaxed ultrafine‑grained structure of the E110 zirconium alloy by the method of RSP

In this work, the task was to investigate the processes of microstructure change occurring in relatively large bulk bars under the action of large plastic deformations. Such large levels of deformation are usually achievable in high pressure twisting of small flat disks, but are difficult to achieve in large bulk bars. The method of radial shear rolling makes it possible to achieve comparable ultrahigh degrees of deformation (~45 mm/mm) in combination with the vortex flow of the metal. Sequential rolling of the E110 zirconium alloy was carried out under extreme conditions on 2 radial shear rolling mills with a total diameter reduction ε = 185 % and a maximum accumulated strain = 46 mm/mm. To assess the level of deformation and its distribution over the section, FEM modeling was carried out in Deform‑3D. The resulting structure was studied by electron microscopy (TEM/SEM). A detailed cross‑sectional study of the EBSD structure was performed with a resolution of 1 mm. A gradient structure with a predominance of an equiaxed ultrafine‑grained structure was found, which was not very pronounced compared to the use of smaller deformations.

Development and Computer Simulation of the New Combined Process for Producing a Rebar Profile

The study presents results of computer simulation by finite elements method of a new metal forming process combining the deformation of a billet with round cross-section on a radial-shear rolling mill and subsequent billet twisting in a forming die with a specific design. To analyze the efficiency of metal processing, the main parameters of the stress–strain state are considered: effective strain, effective stress, average hydrostatic pressure, and Lode–Nadai coefficient. The maximum value of effective strain up to 13.5 is achieved when a screw profile on the billet in the die is forming, which indicates an intensive refinement of the initial structure of the billet. During combined process, the nature of the deformation changes in the transverse direction from the axis of rotation to the surface. The central area of the billet is under the action of tensile stresses. In the peripheral part, compressive stresses grow. In the surface area, Lode–Nadai coefficient is 0.1 approximately, which indicates the high level of shear strain.

Computer simulation of preliminary heat treatment and radial-shear rolling of copper

Computer simulation of preliminary heat treatment and radial-shear rolling of copper

Obtaining an Equiaxed Ultrafine-Grained State of the Longlength Bulk Zirconium Alloy Bars by Extralarge Shear Deformations with a Vortex Metal Flow.

The method of radial shear rolling makes it possible to achieve comparable to high pressure torsion (HPT) method ultrahigh degrees of total strain level in combination with the vortex metal flow character for long-length large bulk bars unable by HPT and many other processes of sever plastic deformation (SPD). Sequential rolling of the Zr-1%Nb alloy was carried out under extreme conditions on two radial shear rolling mills with a total diameter reduction ε = 185% and a maximum total strain level = 46 mm/mm. The strain level and its cross-section distribution assessment by finite element method (FEM) simulation was studied. The final bar cross-section structure type distribution detailed study 1 mm resolution by electron back scatter diffraction (EBSD) mapping was performed. A gradient structure with a predominance of the equiaxed ultrafine-grained (UFG) state was found. The deformation level rising did not allow to refine it in the periphery zone more than that obtained nearly middle of the processing, but it allows for significant change in the axial zone structure. The additional large warm deformations by radial shear rolling have no additional grain refinement effect for already 300-600 nm refined zone. An equiaxed UFG structure was obtained in a relatively large volume of the sample with a reduced gradient towards the non-UFG center zone in regard to known works.

Effect of Radial-Shear Rolling on the Structure and Hardening of an Al-8%Zn-3.3%Mg-0.8%Ca-1.1%Fe Alloy Manufactured by Electromagnetic Casting.

Aluminum alloys are one of the most common structural materials. To improve the mechanical properties, an alloy of the Al-Zn-Mg-Ca-Fe system was proposed. In this alloy, when Fe and Ca are added, compact particles of the Al10CaFe2 compound are formed, which significantly reduces the negative effect of Fe on the mechanical properties. Because of the high solidification rate (about 600 K/s) during cylindrical ingot (~33 mm) production, the electromagnetic casting method (ECM) makes it possible to obtain a highly dispersed structure in the cast state. The size of the dendritic cell is ~7 μm, while the entire amount of Fe is bound into eutectic inclusions of the Al10CaFe2 phase with an average size of less than 3 μm. In this study, the effect of radial shear rolling (RSR) on the formation of the structure and hardening of the Al-8%Zn-3.3%Mg-0.8%Ca-1.1%Fe alloy obtained by EMC was studied. Computer simulation of the RSR process made it possible to analyze the temperature and stress-strain state of the alloy and to select the optimal rolling modes. It was shown that the flow features during RSR and the severe shear strains near the surface of the rod (10 mm) provided a refining and decrease in the size of the initial Fe-containing particles.

The effect of preliminary treatment with subsequent aging on structural-phase state and mechanical properties of β titanium alloy

The effect of aging at 723 K on the structural-phase state and mechanical properties of VT35 titanium alloy after β quenching and various treatments using severe plastic deformation has been studied. It is shown that annealing at 1073 K followed by quenching and aging leading to the precipitation of large α-phase lamellae with volume fraction of 20 % doesn’t have a strengthening effect on the alloy. After processing by radial shear rolling and subsequent aging fine α-phase precipitations in the form of plates and nanometer-sized particles with a volume fraction of 24 % are observed in β-phase grains. However, large areas of β-phase without α-phase precipitates are observed. The strength properties of the alloy after the treatment increase by 40 – 45 %. The processing by the method of multiple pressing leads to the formation of a mixed α / β UFG structure with a grain / subgrain size of 0.11 µm. Subsequent aging leads to the decomposition of the residual β-phase and to a homogeneous distribution of α and β phases in the alloy with volume fraction of α-phase 51 %. The formation of such an UFG structural-phase state leads to an increase in the strength properties of the alloy by a factor of almost two compared to the initial state.

A Mesoscale Study of Fatigue Fracture of Near β Titanium Alloy VT22 after Radial Shear Rolling with Subsequent Aging

A Mesoscale Study of Fatigue Fracture of Near β Titanium Alloy VT22 after Radial Shear Rolling with Subsequent Aging

Simulation of the Kinematic Condition of Radial Shear Rolling and Estimation of Its Influence on a Titanium Billet Microstructure.

The finite element method (FEM) computer simulation of the three-high radial shear rolling of Ti-6Al-4V alloy round billets was conducted using QForm software. The simulation was performed for the MISIS-100T rolling mill's three passes according to the following rolling route: 76 mm (the initial billet diameter) →65 mm→55 mm→48 mm (the final billet diameter). The change in the total velocity values for the points on the radius of the 48 mm diameter billet was estimated while passing the rolls' draft. The relative increase in the accumulated strain was estimated for the same points. Then, experimental shear rolling was performed. Grain sizes of the α- and β-phases were estimated in the cross section of the final billet at the stationary stage of rolling. The grain size distribution histograms for different phases were plotted. An area was found in the billet's cross section in which the trend of change in the total velocity of the points changed. This area represented a neutral layer between the slowing peripheral segments of the billet and the accelerating central segments of the billet. Inside this neutral layer, the limits of the cylindrical surface radius value were estimated. Experimental radial shear rolling was performed to compare the experimental rolling results (the billet microstructure investigation) with the computer simulation results. The computer simulation obtained two estimations of the radius limits: 8-16 mm (based on the analysis of the total velocity change) and 12-16 mm (based on the accumulated strain's relative increment change). The experimental rolling obtained two more estimations of the radius limits: 8.4-19.5 mm and 11.3-19.7 mm-based on the results of the microstructure investigation. It was confirmed that varying the kinematic and deformation parameters of radial shear rolling allows regulation of the thickness of the peripheral fine-grain layer and the diameter of the central coarse-grain layer of the rolled billets.

Analysis of Temperature Influence on Strain-Speed Parameters of Radial-Shear Rolling of Al-Zn-Mg-Ni-Fe Alloy.

The comprehensive analysis of temperature influence on the strain–speed parameters of radial-shear rolling of Al-Zn-Mg-Ni-Fe alloy including the investigation of rheological properties, FEM simulation, and in-depth analytical interpretation of results was carried out. The rolling temperature has significant effect on the kinematic of metal forming, speed parameters, configuration, and length of trajectories. With the decrease in temperature, the speed of metal movement reduces, and this is the same for different components. The greatest decrease is noted for the axial speed component. In general, according to the nature of effect on the strain kinematic state, a temperature reduction of 100 °C (from 500 to 400 °C) acts similarly to a decrease in feed angle of about 4° and, in particular, increases the rolling time, nonuniformity of deformation, tightening, and temperature effect of deformation heating.

Analysis of temperature-deformation conditions for rolling aluminum alloy Al–Mg–Sc based on FEM modeling

The article discusses the features of Al–Mg–Sc aluminum alloy radial shear rolling (RSR). The RSR process was modeled by the finite element method in the QForm 3D program with the variable elongation ratio per pass and rolling speed. The results obtained were used as a basis for studying the temperature field of the rod in the deformation zone taking into account the cyclic nature of deformation and the configuration of flow paths. It was found that the temperature field in the deformation zone is determined by significant differences in the metal flow path geometry in surface layers and in the axial zone. When the elongation ratio is varied from 1.6 to 2.4, heating occurs inconsistently from the center to the surface. The highest temperature rise occurs for an area that is located ~0.3R from the surface. For the axial zone, temperature variation in the deformation zone occurs smoothly and with an insignificant temperature difference of 5–10 °C. Highest temperature fluctuations are observed on the rod surface, and this is explained by deformation heating and simultaneous contact with a cold roll during each deformation cycle. As the rolling speed decreases, a picture of the rod temperature field distribution in the deformation zone is observed with the temperature in central layers exceeding the surface temperature. Due to the long time of the rod contact with the roll, the surface temperature fluctuates up to 40–50 °C at each deformation cycle. As the rolling speed rises, the amplitude of temperature fluctuations on the surface decreases, and deformation heating increases. The data obtained on the relationship between control process parameters and rod temperature field variation can be useful in the design of rolling process modes.

Effect of process parameters on the microstructure and mechanical properties of bars from Al-Cu-Mg alloy processed by multipass radial-shear rolling

The study of microstructure and mechanical properties formation of A2024 alloy obtained by the multipass radial-shear rolling (RSR) method is discussed in this article. FEM simulation was carried out that made it possible to evaluate the influence degree of rolling temperature–velocity parameters on the strain state of material. It has been found the increase in rotary velocity of rolls significantly influences on the deformation heating of bar after RSR (predominantly in its surface layer). The combination of rolling temperature–velocity conditions at selection of deformation regime has complex effect on structure and properties formation. The analysis of sizes and distribution of phase particles has shown that the rolling at lower temperatures allowed to increase the mechanical strength due to the more intensive refinement of undissolved Fe-containing phase. The gradual decrease in the rolling temperature in each pass makes possible to achieve the high strength (UTS ~ 430 MPa and YS ~ 255 MPa) while maintaining the ductility level ~ 15%, that are comparable to ones obtained at some severe plastic deformation (SPD) methods.

Development and experimental testing of the technology for producing deformed bars of D16(T) alloy from continuously cast billets of small diameter with low elongation ratios

The article describes the development and pilot-scale testing of the technology for producing bars of the D16(T) aluminum alloy by radial-shear rolling from continuously cast billets with a diameter of 72 mm in several passes. The actual dimensions of rolled bars were within the ±0.16 mm tolerance for all bar diameters, which significantly surpasses the GOST 21488-97 requirements. According to the results of tensile tests, the values of ultimate strength, conventional yield strength, relative elongation and relative reduction were determined. Ultimate strength and relative elongation requirements specified by regulatory documents for the D16(T) alloy were met with a total elongation ratio of more than 4.2. In terms of plastic properties, the obtained bars surpass the GOST requirements by 2.1–2.5 times in the entire range of elongation ratios investigated starting from 2.07. At the same time, there is an increase in the relative elongation by 5.7–6.8 times in comparison with the initial cast state. The microstructure and morphology analysis conducted for secondary phases showed that with a decrease in the bar diameter (with an increase in the total elongation ratio), the average particle size of the α(AlFeMnSi) phase insoluble in the aluminum matrix decreases, which is a consequence of deformation processes developed during rolling. Additional grinding of inclusions during deformation processing can significantly reduce the possible negative effect of the insoluble phase on the mechanical properties of resulting bars, in particular on the plasticity properties. The microstructure analysis showed that bars after rolling and heat treatment are free from cracks, looseness, delamination, and other defects and meet the requirements of GOST 21488-97.

Effect of forging temperature on the structure, mechanical and functional properties of superelastic Ti-Zr-Nb bar stock for biomedical applications

Ti-Zr-Nb shape memory alloys exhibit a unique combination of properties that make them suitable for bone implants: low Young’s modulus, superelastic behavior, superior corrosion resistance, and non-toxicity of all the constitutive elements. In this study, superelastic Ti-19Zr-14Nb (at.%) alloy was subjected to a combination of radial shear rolling at 900°C and rotary forging in a temperature range from 500 to 700°C to form long-length bar stocks for bone implants fabrication. Features of the grain structure, phase composition, mechanical and functional properties of the long-length bar stocks were analyzed using light microscopy, X-ray analysis, as well as during mechanical and functional tests. It was shown that after radial shear rolling at 900°C, a heterogeneous grain structure was formed over the cross-section of the bar stock, and this structure was inherited after the subsequent rotary forging at 500°C. With an increase in the forging temperature, the structural heterogeneity is eliminated and the grain size increases, while the hardness and strength characteristics of the material decrease. After rotary forging at 700°C, the alloy manifests the best combination of structural, mechanical, and functional characteristics. In this state, the long-length bar stock demonstrates a homogeneous grain structure with a certain fraction of a dynamically polygonized substructure of β-phase, a satisfactory strength (UTS ≈ 580 MPa), a low Young’s modulus (E ≈ 35 GPa), the high difference between dislocation and phase yield strength (Δσ ≈ 280 MPa), and a relatively large amount of superelastic recovery strain (εrSEmax ≈ 3.1%).

Radial-Shear Rolling as a New Technological Solution for Recycling Bar Scrap of Ferrous Metals

Recycling of waste, both ferrous and non-ferrous metals is a useful process for the economy of any country. In this paper, a new technology for recycling bar scrap of ferrous metals by rolling on radial-shear rolling mills was proposed to obtain a marketable product in the form of bars with an ultrafine-grained gradient structure. Studies have shown that the deformation of the rod of scrap pieces of rebar from steel 18G2S mill of radial-shear rolling can significantly dispersed structure with obtaining the gradient ultrafine-grained structure, and this in turn leads to an increase of the mechanical characteristics of this steel grade. Thus, the tensile strength of steel grade 18G2S deformed at the radial-shear rolling mill was 620 MPa (at the initial value of 365 MPa).