Severe Plastic Deformation Process Research Articles

A new methodology for improving and testing the performance of hip prosthesis through advanced severe plastic deformation processes

A new methodology for improving and testing the performance of hip prosthesis through advanced severe plastic deformation processes

Simulation of the Process of Temperature Field Changing of a Zr–1%Nb Zirconium Alloy Billet During Equal-Channel Angular Pressing

Using mathematical modeling in the QFORM software package, the data on the temperature distribution of a billet made of a zirconium alloy E110 (Zr–1%Nb) in its longitudinal and transverse sections during an equal-channel angular pressing (ECAP) were obtained. The initial data on the geometric parameters of the billet and the die of the ECAP unit are presented, and the conditions for carrying out the process of severe plastic deformation, as well as the chemical composition and physical characteristics of the Zr–1%Nb alloy necessary for carrying out the computational modeling are described. The values of the billet temperature were determined for the calculated moments of the passage of the billet through the junction of the die channels, which corresponded to 25%, 50%, and 75% of its length. It is shown that during the ECAP process at a given pressing speed, in the section corresponding to the junction of the matrix channels, an increase in the billet temperature relative to its initial heating occurred by an amount of about 10 ºC.

Design of thermomechanical processes for tailored microstructures: Methodology and application to nanocrystalline titanium alloy Ti-13Nb-13Zr (NanoTNZ)

Thermomechanical processes enable tailoring of material properties and microstructures for advanced products. In medical technology, next-generation titanium implants require tailored material properties to improve health and quality of life. However, the interaction correlation between process parameters and material properties poses a major challenge for the design of thermomechanical manufacturing processes.In this paper, we present a methodology for the design of thermomechanical processes to achieve tailored microstructural properties through forming technology and heat treatments. The methodology consists of five systematic steps to address the complexity of multiphysical coupling relationships between temperature, stress, microstructure and alloy composition, and to provide a guideline for effective implementation. It is applied to the production of nanostructured Ti-13Nb-13Zr (NanoTNZ) alloy for dental implants. The designed process of severe plastic deformation, recrystallization treatment and aging lead to nanostructured microstructures smaller than 200 nm. The resulting mechanical properties (UTS > 980 MPa, Young’s modulus of 73 GPa) meet the desired goals for improved biomedical implant-bone interactions. The tailored material properties and microstructures of NanoTNZ are therefore highly promising for use as an implant material.The case study demonstrates the importance of a systematic method to manage the complexity of multiphysical coupling relationships in the design of thermomechanical processes to enable tailored microstructures for advanced materials and products.

Nanostructured bulk HPT β Ti-42Nb alloy as biomaterial for implants obtained directly from micrometric powders

The effect of high-pressure torsion (HPT) processing on mechanical properties in a β Ti-42Nb alloy micrometric powder consolidated in a nanostructured bulk disc through severe plastic deformation for biomedical applications is investigated. XRD, SEM and TEM/ASTAR characterization are used to characterize microstructure of the original micrometric powder and the consolidated disc of β Ti-42Nb alloy after HPT. The results show that severe plastic deformation processing improves Vickers hardness of β Ti-42Nb alloy, and leads to a low modulus bulk material with E = 63 GPa after HPT, comparable with that of as-cast alloy. The obtaining of nanostructured grain size around 55 nm bulk β Ti-42Nb alloy consolidated through HPT from micrometric atomized powder opens perspectives of applications as biomedical implants.

Formation of property gradient in coarse-grained niobium using a wedge tool: Experiment and analysis

We introduce a novel severe plastic deformation process for coarse-grained niobium, which employs a tool with an inclined (wedge) surface for deforming the material by a reverse shear scheme. The process increases the intensity of shear deformations and the depth of plastic deformation in the body of the workpiece when a wedge tool acts on its surface. The essence of the process is in the repeated displacement of the workpiece material in opposite directions during the asymmetrical introduction of a wedge tool until the required degree of deformation is accumulated in the tool-affected volume. This deformation scheme applies a 15° angle wedge tool to a 21-mm high workpiece. After nine cycles of plastic deformation, a gradient of the accumulated degree of deformation in the range of true strain e = 0.3–4.5 was created. At maximum deformation, the microhardness of the workpieces increased by 1.86 times and the tensile strength by 1.6 times. Fractograms show a significant influence of the accumulated degree of deformation on the nature of the fracture. The finite element method simulation of the deformation process showed that creating a uniformly strengthened layer requires at least five deforming operations. For example, the proposed reverse shear process with a wedge tool can be applied to improve the structure of the surface layers of niobium ingots for subsequent forming. Due to the creation of a significant gradient of properties, the reverse shear process can be used as an express method for determining the mechanical characteristics of different materials in a wide range of accumulated degree of deformation.

Ferromagnetism in High Entropy Cantor alloy triggered and tuned by severe plastic deformation

The process of severe plastic deformation (SPD) introduces unique conditions to materials, leading to the emergence of novel properties. This research specifically investigates the observation of deformation-induced ferromagnetism resulting from SPD processing. High-pressure torsion (HPT) is utilized to process both single-phase and nanocomposite high entropy alloys (HEAs). Vibrating sample magnetometry (VSM) confirms that HPT processing triggers the development of ferromagnetic properties. The distribution and alignment of magnetic domains post-SPD treatment are further examined using differential phase contrast scanning transmission electron microscopy (DPC STEM). Atom probe tomography (APT) analysis suggests that this phenomenon stems from the localized enrichment of ferromagnetic elements, particularly Ni, induced by deformation. This observation underscores the ‘cocktail effect’ in HEAs, whereby interactions between different elements has led to this unique magnetic behavior. Additionally, deliberate mechanical mixing of the CoCrFeMnNi alloy with a HfNbTaTiZr HEA, comprising non-ferromagnetic constituents, introduces a large rotational strain that alters the ferromagnetic properties. This mixing facilitates a transition from a random orientation of magnetic domains, as seen in the HPT-processed single CoCrFeMnNi alloy, to a coordinated alignment within the nanocomposite HEA.

Discovery of white etching areas in high nitrogen bearing steel X30CrMoN15-1: A novel finding in rolling contact fatigue analysis

White etching areas (WEA) and white etching cracks (WEC) are frequently linked to premature bearing failure in conventional high carbon bearing steels like 100Cr6 (SAE 52100). In contrast, no WEA/WEC has yet been reported for the high nitrogen bearing steel X30CrMoN15-1 (SAE AMS 5898). Thus, the present study proves for the first time that X30CrMoN15-1 is also susceptible to develop WEA/WEC under rolling contact fatigue (RCF) when pre-charged with hydrogen. RCF tests conducted in parallel without hydrogen pre-charging resulted in RCF damage only, which identifies hydrogen as an active agent for WEA/WEC formation in X30CrMoN15-1. These findings correspond to the fact that hydrogen diffusion during RCF is often considered to cause or accelerate the formation of WEA/WEC. Additionally, it is observed that the M2(C, N) and M23C6 precipitates of the martensitic microstructure of the X30CrMoN15-1 do not entirely decompose during the WEA formation process as observed for M3C precipitates in 100Cr6. In conclusion, the results for X30CrMoN15-1 strongly suggest that the formation of WEA is driven by a hydrogen-activated local severe plastic deformation process, which initiates continuous dynamic recrystallisation, leading to the characteristic nano-ferritic grains observed in WEA. Also, the highly stable and self-regenerating passive chromium-oxide layer of X30CrMoN15-1 mitigates the risk of WEA/WEC failure during typical RCF operation by hindering the formation and adsorption of ionic hydrogen. Hence, this study emphasises the importance of protecting the base material against hydrogen ingress to delay WEA/WEC formation.

Ball milling and annealing effect in structural and magnetic properties of copper ferrite by ceramic synthesis

This study aims to better understand the relationship between the microstructure and magnetic properties of copper ferrite, which is an inverse spinel that present a body-centered tetragonal structure associated with a remarkable Jahn–Teller (JT) effect. For this goal, a sample has been synthesized by the ceramic route from a stoichiometric mixture of high-purity CuO and Fe2O3 powders activated mechanically in a high-energy planetary ball mill. This sample was calcined in air furnace at 1000 ºC for 6 h. As synthetized sample with a cubic structure was divided into two parts and one of them was annealed at 650 ºC for 3 h and slowly cooled to room temperature to obtain a pure tetragonal spinel sample. Furthermore, these two samples were subjected to the same processes of severe plastic deformation by milling for up to 70 h and subsequent annealing at temperatures ranging between 300 and 600 ºC to obtain samples with a mixture of phases in different proportions. For the cubic one, there is no change in its structure due to milling, always remaining 100 % cubic, and the evolution in the saturation magnetization was related to the changes in the density of defects present. On the other hand, copper cations are always found in the octahedral sites of spinel with a tetragonal structure. The small decrease in the degree of inversion to 0.95 induced by milling in this sample is capable of breaking the JT distortion, giving rise to the appearance of a cubic phase. This work demonstrates how the structure, microstructure, defects like stacking faults and deformation twins, and degree of inversion of the different phases are related to changes in magnetic properties.

Effect of Temperature and Strain on Bonding of Similar AA3105 Aluminum Alloys by the Roll Bonding Process

Accumulative roll bonding (ARB) is a severe plastic deformation process that enables the production of materials with ultrafine microstructures and enhances the characteristics of the base material, particularly in metal matrix composites. The primary objective of this study is to experimentally investigate the bonding strength in AA3105 strips that underwent the roll bonding process, with a specific focus on examining the influence of temperature and reduction rate on bonding. Three temperature levels (200 °C, 300 °C, and 400 °C) and three thickness reduction levels (35%, 50%, and 65%) were considered. The T-peel test was carried out to assess the bonding quality. It was employed to determine the peak force required to separate the two bonded strips. Additionally, ANOVA analysis was performed to develop a regression equation for analyzing peak force. Optical microscopy was used to evaluate the interface bonding quality in the longitudinal section. The results indicate that the bonding strength increases with both temperature and percentage reduction.

Nanostructured Titanium with Ultrafine‐Grained Structure as Advanced Engineering Material for Biomedical Application

Titanium and its alloys are popular materials for medical application, particularly in implant devices, where high mechanical properties and osseointegration are critical factors for successful implantation. In this work, the progress in the studies of nanostructured commercially pure Grade 4 titanium (nanoTi) is demonstrated, in which an ultrafine‐grained structure with nanoscale grain size is formed using severe plastic deformation processing. Nanostructured Grade 4 Ti has a very high strength, and its physical nature and strengthening mechanisms are analyzed herein. NanoTi proved also to have very high osseointegration during in vivo experiments. At the same time, the highest biofunctionality is demonstrated by the etched nanoTi samples with pronounced surface roughness, the latter being revealed from precise roughness measurements. The present study provided convincing evidence of accelerated bone formation on nanoTi, which is very promising for manufacture of dental and maxillofacial implants.

Effect of shot peening on surface characteristics and high-temperature corrosion behaviour of super 13Cr martensitic stainless steel

Super 13Cr, as an economy stainless steel (SS) for oil country tubular goods, needs stable corrosion resistance in high-pressure and high-temperature (HPHT) downhole medium. Severe plastic deformation (SPD) are the surface modification technology to improve mechanical properties, fatigue behavior and corrosion resistance of metals, and shot peening (SP) has been the most widely used SPD process. However, there are quite limited studies about the microsutructure evolution, residual stress, and high-temperature corrosion behavior of SP-treated martensitic SS. In this study, super 13Cr martensitic SS was treated by SP with various air pressures and nozzle speeds. The surface characteristics and high-temperature corrosion behaviour in 3.17 mol/L K2HPO4 solution were investigated through finite element model analysis, characterization of residual stress and microstructure, as well as electrochemical and stress corrosion cracking (SCC) tests at 160 °C and 10 MPa. The results showed that SP-treated super 13Cr could generate high-level compressive residual stress and SPD microstucture, including nano-sized equiaxed grains, gradient lamellar structure and fragmented carbides. Increasing air pressure contributed to achieve uniform nanocrystalline, but tended to generate high dislocation density and surface defects. The improving effect of SP treatment at low air pressure of 0.15 MPa on passivation ability was limited, and high air pressure adversely impacted corrosion resistance. SP-treated specimens showed high SCC susceptibility, due to the introduction of more surface defects, high angle grain boundaries, and dislocations.

Nanostructuring and Hardness Evolution in a Medium‐Mn Steel Processed by High‐Pressure Torsion Technique

Severe plastic deformation (SPD) is performed on a newly developed medium‐Mn steel with the composition of Fe–7.66Mn–2Ni–1Si–0.23C–0.05Nb (wt%) to achieve a nanocrystalline microstructure. The SPD process utilizes the high‐pressure torsion (HPT) technique, resulting in a nominal shear strain of approximately 36 000% after processing the disk for 10 turns. In X‐Ray diffraction line profile analysis, an increase in dislocation density to around 230 × 1014 m−2 is observed. In addition, under high strains, a face‐centered cubic (fcc) secondary phase emerges within the body‐centered cubic (bcc) matrix. In analytical transmission electron microscopy, using energy‐dispersive X‐Ray spectroscopy, it is indicated that the secondary‐phase particles are enriched in Al, Mn, and Si. As the strain imposed during HPT increases, the simultaneous rise in dislocation density and nanostructuring lead to material hardening. However, the partial phase transformation from bcc to fcc contributes to material softening. As a result of these two opposite effects, the hardness exhibits a non‐monotonic variation with the shear strain, displaying, for 10 turns of HPT, a lower hardness compared to fewer turns, despite the continuous increase in dislocation density and decrease in crystallite size.

Co‐Deformation in Severely Deformed Multiphase Crystalline Metallic Systems: Physical Mechanisms, Intrinsic Limitations, and Perspectives

The deformation of multiphase metallic alloys or metal matrix composites by forming processes such as rolling or drawing requires the co‐deformation of phases. Severe plastic deformation processes have extended possibilities with the ability to produce unique nanoscaled structures through the formation of strain‐induced super‐saturated solid solutions, the fragmentation of second‐phase particles, or ultimate co‐deformation down to the nanoscale. Based on various examples, the fundamental mechanisms of co‐deformation are addressed. Parameters that promote the extension of existing heterophase boundaries are discussed, and some possible atomic‐scale mechanisms involving dislocation activities based on geometrical and energetic considerations are proposed. Finally, the physical limits of co‐deformation are considered before suggesting research directions that might be followed to develop fundamental knowledge and applications in the field.

Corrosion Activity of Ultrafine-Grained Pure Magnesium and ZK60 Magnesium Alloy in Phosphate Buffered Saline Solution.

The magnesium alloy ZK60 is a promising candidate as a material for biodegradable implants. One of the most important factors for biodegradable implants is the modification of their corrosion behavior to match the requirements for the healing bone or tissue. The corrosion behavior can be influenced by different factors, among them the grain size, which can be changed by severe plastic deformation processes such as High Pressure Torsion Extrusion (HPTE). This study focuses on the corrosion behavior of samples of pure magnesium and ZK60 before and after HPTE, and the influence of the microstructure on the corrosion activity. The samples are subjected to immersion tests in phosphate buffered saline solution (PBS). The corrosion activity is defined by the emerging hydrogen volume from the corrosion process which is collected and by subsequently observing the resulting sample surfaces. The findings of this study suggest that pure magnesium shows lower corrosion activities than ZK60 and that HPTE processing leads to higher corrosion activities in PBS.

Evolution of Microstructure of Copper and Its Alloys during Severe Plastic Deformation Process

Evolution of Microstructure of Copper and Its Alloys during Severe Plastic Deformation Process

Heterostructuring of BN-CoCrFeMnNi high-entropy alloy via severe plastic deformation

Recent material design aims at fabricating heterogeneous structures to overcome the strength-ductility trade-off. A severe plastic deformation process is adopted to a multi-interstitial high-entropy alloy to form precipitate-rich and precipitate-lean domains. By this approach, the alloy achieved a yield strength of ∼1020 MPa with a tensile elongation of ∼34 %.

On Dynamic Recrystallization during the Friction Stir Processing of Commercially Pure Ti and Its Influence on the Microstructure and Mechanical Properties

Friction stir processing (FSP), a severe plastic deformation process, was applied on commercially pure Ti to obtain an improved microstructure. The process yielded a refined microstructure and higher mechanical properties at room temperature (RT). Yet the microstructure was found to contain bright bands demonstrating high hardness values of about 500 HV. High-resolution scanning electron microscopy (HRSEM) as well as electron backscattering diffraction (EBSD) analysis indicated that these bands were composed of extra-fine equiaxed α-Ti grains with an average radius of 1–2 microns. In addition, a retained β phase was detected at the boundaries of these α-Ti grains, together with a small quantity of separate β grains. The results of a fractography study conducted on broken tensile specimens showed that the material that underwent FSP was free of defects and that the fracture started at these bands. It is proposed that these bright bands are due to excessive deformation occurring during the processing stage, leading to an accelerated dynamic recrystallization (DRX) process. In turn, these heavy deformation regions act as a strengthening constituent, making the material superior to the parent material as far as its mechanical RT properties are concerned. Consequently, this means that the FSP of CP-Ti has the potential to serve as an industrial means of improving the mechanical properties of the material.

Microstructure, aging behavior, and friction and wear properties of ultrafine-grained 7050 aluminum alloy produced by cryogenic temperature extrusion machining

Cryogenic temperature extrusion machining (CT-EM), as a novel cryogenic temperature severe plastic deformation (CT-SPD) process, is an effective method to produce ultrafine-grained (UFG) materials. In this paper, the microstructure, microhardness, friction and wear properties of the UFG chips prepared by CT-EM and room temperature extrusion machining (RT-EM) were analyzed. The results show that CT-EM has a better grain refinement effect. The grain size of the CT-EM samples is smaller, the dislocation density is larger, and the microhardness is higher. After aging treatment, a large number of small secondary precipitates (η '/η) appear in the microstructure of the samples, which further improves the microhardness. This is the result of a synergistic effect of fine grain, dislocation, and precipitation strengthening. Cryogenic treatment can increase the precipitation kinetics of the secondary phase and shorten the time for the samples to reach peak hardness. The CT-EM samples have a lower friction coefficient and wear mass. With the increase of the machining velocity, the wear mechanism of the samples changes from abrasion wear to oxidation, adhesion, and fatigue wear.

Strength and formability improvement of ECARed aluminum alloy 6061 sheets using the artificial aging heat treatment

In the current research, the experimental investigation of the mechanical characteristics of 6061 aluminum alloy, which was subjected to Equal Channel Angular Rolling (ECAR) – A Severe Plastic Deformation Process – and artificial aging heat treatment, has been discussed. By performing the ECAR, the strength of the material increases, but the formability will be reduced. Consequently, the usage of this alloy has been limited. The artificial aging heat treatment process has been proposed after the ECAR operation, and the strength, hardness, and formability of the material have been investigated. In this regard, remarkable results were obtained. By controlling the aging time and temperature on the ECAR piece, not only the strength increased but also the ductility increased. Moreover, an artificial neural network was used to find the optimal aging time and temperature. Finally, the best aging time and temperature ranges to achieve the most desirable mechanical properties were provided using the neural network. The result show 150% increase in strength and 50% in formability by performing controlled-artificial aging heat treatment with ECAR process.

Influence of Equal Channel Angular Pressing Technique on Mechanical Properties, Corrosion Resistance, and Microstructural Behavior of Al-Alloy 5083

Introduction: During severe plastic deformation (SPD) processing, aluminum alloys exhibit moderate strength and ductility. Nevertheless, the materials' ductility, as determined by tensile testing, does not accurately represent their capacity for plastic deformation. After the tensile test, its material, aluminum alloy 5083, was observed to be super ductile. Method: The results of a more thorough plasticity analysis—applied for the first time to material following SPD processing—are presented in this paper. The aluminum alloy 5083 is examined in the patent both before and after equal channel angular pressing (ECAP). A highly effective aluminum alloy 5083 specimen preparation was suggested. Under heated temperatures, the process involves severe plastic deformation. Optical microscopy and scanning electron microscopy (SEM) were used for micro-structural research in order to look at the distribution of second-phase particles and the evolution of grain structure. Furthermore, Vickers micro-hardness testing was utilized to assess the mechanical characteristics of the alloy after processing. The outcomes showed that after ECAP processing, there was a significant decrease in grain size and an increase in micro-hardness. Result: Additionally, the production of a finer microstructure with a more uniform distribution of strengthening precipitates was clarified by electron microscopy (SEM). The micro-structural evolution and mechanical behavior of aluminum alloy 5083 under ECAP are well-explained in this patent, which may lead to improved performance in structural applications. This method can be used to forecast fractures in plastic deformation processes and estimate the final plasticity of the materials for various stress-strain states after ECAP processing, as well as the mechanical properties discussed. Conclusion: Due to its unique mechanical qualities, aluminum alloy 5083 shows great potential in a variety of structural applications. The effects of Equal Channel Angular Pressing (ECAP) on the hardness and microstructure of aluminum alloy 5083 were examined in this patent work. result: The specimen's mechanical characteristics are at their finest following a single deformation when the temperature reaches 300°C. Compared to the original specimen, the tensile strength observed enhanced after the fourth pass, and breaking elongation (28.3%) was improved. Through second-phase strengthening and fine-tuning, the recrystallized grains and second-phase particles increase the material's strength.