Plastic Deformation Process Research Articles

INVESTIGATION INTO THE THERMAL DEFORMATION BEHAVIOR AND THE ESTABLISHMENT OF A CONSTITUTIVE RELATIONSHIP FOR Mn-Cr-Ni-Mo STEEL

Isothermal compression tests were conducted on Mn-Cr-Ni-Mo steel at temperatures ranging from 1173 K to 1473 K and strain rates from 0.01 s–1 to 10 s–1 using a Gleeble-3800 thermal simulation tester. Four constitutive models for Mn-Cr-Ni-Mo steel, namely the Arrhenius model, Fields-Backofen model (F-B), original Johnson-Cook model (J-C), and the improved Johnson-Cook model (mJ-C) were established. A correlation coefficient (R) and the average absolute relative error (AARE) were employed to evaluate the predictive capability of these four models. Among them, the Arrhenius model exhibited superior accuracy in predicting the behavior of Mn-Cr-Ni-Mo steel. It and the isothermal thermal compression finite-element model were imported into Deform-3D software for a numerical simulation, aiming to analyze the distribution law of the equivalent stress field. A comparison was made between the time-stress data obtained from numerical simulation under different conditions and that from the isothermal compression tests. The results demonstrate good agreement between the time-stress curves of the numerical simulation and the experimental measurements, indicating that the established Arrhenius model can effectively simulate the thermal deformation of Mn-Cr-Ni-Mo steel. These research findings provide valuable fundamental data for simulating the plastic-deformation process of Mn-Cr-Ni-Mo steel.

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.

Hot Deformation Characteristics and Dynamic Recrystallization Mechanisms of a Semi-Solid Forged AZ91D Magnesium Alloy.

Magnesium alloys show great promise in high-speed transport, aerospace, and military technology; however, their widespread adoption encounters challenges attributed to limitations such as poor plasticity and strength. This study examines the high-temperature deformation of semi-solid forged AZ91D magnesium alloy through a combination of experiments and simulations, with a focus on comprehending the influence of deformation conditions on dynamic recrystallization (DRX). The findings disclose that conspicuous signs of DRX manifest in the yield stress curve as strain increases. Additionally, decreasing the strain rate and temperature correlates with a reduction in both yield stress and peak strain, and the activation energy is 156.814 kJ/mol, while the critical strain and peak strain remain relatively consistent (εc=0.66208εp). Microstructural changes during high-temperature deformation and the onset of DRX are thoroughly examined through experimental methods. Moreover, a critical strain model for DRX and a predictive model for the volume fraction of DRX were formulated. These equations and models, validated through a combination of experiments and simulations, serve as invaluable tools for predicting the mechanical behavior and microstructural evolution, which also establishes a foundation for accurately predicting the deformation behavior of this alloy. By analyzing the hot deformation characteristics and dynamic compression mechanism of the newly developed semi-solid forging AZ91D magnesium alloy, a numerical simulation model can be effectively established. This model objectively reflects the changes and distributions of stress, strain, and rheological velocity, providing a scientific basis for selecting subsequent plastic deformation process parameters and designing mold structures.

Finite Element Simulation of Multi-Pass Rolling of a Pure Aluminum Target under Different Rolling Routes and Methods

By coordinating the rolling direction and mode, a multi-rolling plastic deformation process for an aluminum (Al) sputter target is proposed to achieve multiple excellent properties, including a uniform and fine grain structure and low defect risk, which are significant in producing high-quality sputtered films. In this work, therefore, DEFORM 3D 10.2 software is adopted to establish three strategies, clock-synchronous rolling, cross-synchronous rolling, and clock–snake rolling. The effect of different rolling routes and modes on the metal flow velocity (MFV), effective strain distribution (ESD), grain size distribution (GSD), damage, and rolling force (RF) are comparatively investigated. The simulation results show that clock–snake rolling can increase the MFV and effective strain by producing a deeper deformation than the others. It provides sufficient energy for dynamic recrystallization to promote grain refinement. In combination with the microstructure homogeneity promoted by the clock rolling route, the GSD from 6.5 to 44.3 μm accounts for about 80.5% of all the grains because of the fact that a randomly oriented grain region is full of high-angle grain boundaries. Compared with the synchronous rolling mode, the decrement in RF maximum reaches up to 51% during the asynchronous rolling process because component energy is consumed to form cross-sheering stress. It remarkably reduces the risk of defects, with a damage value of less than 73%, and simultaneously improves energy efficiency owing to smaller and uniform grains caused by less RF. The results obtained in this work are of great significance as they can guide practical production in the metal target industry.

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.

Influence of the Plastic Deformation Process on the Residual Stresses and Hardness of an Al-5Mg Alloy.

The service behavior of ductile metallic materials, when they have previously undergone technological plastic deformation, depends on the deformation conditions. These are represented, among others, by the deformation rate, the process temperature, the applied pressures, and the introduced stresses, as well as other process variables. The investigation of the mechanical properties obtained after plastic deformation is an important means that contains two characteristics: on the one hand, to determine to what extent the parameters of the technological manufacturing process influence the main characteristics of the final component; and, on the other hand, on the basis of these characteristics, to analyze whether the component subjected to plastic deformation will be able to function reliably and safely. In the present work, an experimental study was made of the residual stresses developed and hardnesses obtained both in the immediate vicinity of a highly plastically deformed area and in an area previously obtained by rolling, without additional plastic deformation. For the determination of the residual stresses, the tensiometric rosette drilling method was used. By determining the same quantities in a non-plastically deformed area, significant changes in the values of the two quantities in the plastically deformed area were found. An increase in the maximum principal normal stresses by approx. 60 MPa and an increase in the Rockwel hardness by approx. 10 HRC was found. A sample was taken from the area under a plastic deformed circular shape, and was analyzed microscopically.

Influence of Single- and Double-Aging Treatments on the Mechanical and Corrosion Resistance of Alloy 625

Nickel–chromium–molybdenum Alloy 625 exhibits an excellent combination of mechanical properties and corrosion resistance. However, the high-temperature plastic deformation process and the heat treatment represent critical aspects for the loss in mechanical strength by grain coarsening. This detrimental behavior is worsened by the absence of phase transformation temperatures. However, the chemical composition permits slow precipitation-hardening response upon single aging. Therefore, when the soft- or solution-annealed condition is associated with insufficient mechanical properties, this potentiality can be exploited to improve the mechanical strength. Since the 𝛾″ precipitation can be accelerated by double-aging treatment, different time–temperature combinations of double aging at 732 °C and 621 °C are investigated. The simultaneous precipitation of intergranular carbides can dramatically affect the corrosion resistance. Such an undesired phenomenon occurs very quickly at 732 °C, but it is obtained only after very long exposure times at 621 °C. For this reason, a performance chart is developed to compare all the tested conditions. In particular, single aging at 621 °C for 72 h and 130 h are associated with an acceptable combination of mechanical and corrosion properties. Double aging permits a conspicuous acceleration of the aging response. For instance, with double aging at 732 °C 3 h and 621 °C 72 h, it is possible to obtain the same mechanical properties of single aging at 621 °C for 260 h. Such acceleration is accompanied by a more critical corrosion behavior, especially because of the primary step. However, even after its optimization, none of the tested conditions were acceptable.

The reduced order model for creep using dynamic mode decomposition

Given the computational challenges associated with finite element methods in analyzing creep behavior in high-temperature components, this work presents an advanced method for modeling thermal creep in complex structures through a reduced order model (ROM) developed via dynamic mode decomposition (DMD). The results indicate that the ROM using DMD can predict long-term structural responses related to creep based on short-term data with high accuracy, enhancing significantly computational efficiency. The application of ROM allows for the rapid estimation of creep effects in complex structures, like monoliths in the MegaPower reactor, thereby improving the design efficiency. The eigenvalues of the creep related ROM all fall in the unit circle on the complex plane, indicating that creep is a stable development process. The DMD with improved time mode coefficient can reconstruct strain-rate related plastic deformation and cyclic visco-plastic deformation process. Additionally, we derive the necessary stress updating algorithm and consistent tangent operator matrix for the 316H unified visco-plastic constitutive equation in 2023 edition ASME code, ensuring accurate modeling of material creep behavior under high temperatures in this paper. This work provides a valuable tool for the safe design and operation of critical components in nuclear engineering and other high-temperature applications.

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.

Crack growth and fracture mechanics of CuCrFeNiCo high-entropy alloy during tension testing

In this work, the crack growth and fracture mechanics of CuCrFeNiCo high-entropy alloy (HEA) during tension process are studied through molecular dynamics simulation method. The single-crystalline, nanocrystalline, and twinned-nanocrystalline CuCrFeNiCo HEA samples with an initial crack are prepared. The influences of boundary conditions, crack length and crystallographic orientation are considered in detail. The results indicate that the phase transition from face-centered cubic (FCC) structure into hexagonal close-packed (HCP) structure and the appearance of Shockley dislocations are the majority in all samples. The dislocations appear most densely in the twinned-nanocrstalline sample and most sparsely in the single-crystalline sample. The growth of the initial crack combined with the formation and expansion of new cracks along the grain boundaries (GBs) is the determining factor in the fracture mechanics of the CuCrFeNiCo HEA samples. The deformation capacity of the samples with free boundary conditions along the y-axis is better and the plastic deformation process is longer than the samples with periodic boundary conditions along the y-axis. The tensile strength values of the CuCrFeNiCo HEA samples change significantly in the range from 2.61 GPa to 7.75 GPa when changing the simulation conditions. The von Mises stress in the grains is markedly lower than that in the GBs.

Solid-state recycling of magnesium and its alloys via plastic deformation: An overview of processing and properties

The increasing demand for primary magnesium production poses significant environmental challenges, aggravated by the limited availability of raw materials, which can hinder supply. Consequently, the recycling of magnesium chips and waste is gaining importance. While conventional remelting techniques are prevalent as they suffer from drawbacks including high energy consumption, material loss, low purity, and inferior mechanical properties. Solid-state recycling (SSR) via plastic deformation processes has been introduced as a promising alternative for producing ultrafine-grained (UFG) magnesium materials with outstanding properties. Despite the absence of any reviews on SSR using plastic deformation methods for magnesium, this paper offers a detailed examination of SSR techniques. The mechanisms of bonding and grain refinement, crucial for determining the final properties of recycled magnesium, are explored. Furthermore, the discussion delves into corrosion, an essential aspect concerning magnesium and its alloys. Ultimately, the impact of various parameters such as process temperature, level of shear strain, chips size, and hydrostatic pressure on the quality of the final sample, to be used as guidance for the production of better-qualified specimens was examined.

Mechanisms of Low-Temperature Dislocation Motion in High-Entropy Al0.5CoCrCuFeNi Alloy

An analysis of the processes of plastic deformation and acoustic relaxation in a high-entropy alloy, Al0.5CoCrCuFeNi, was carried out. The following were established: dominant dislocation defects; types of barriers that prevent the movement of dislocations; mechanisms of thermally activated movement of various elements of dislocation lines through barriers at room and low temperatures. Based on modern dislocation theory, quantitative estimates were obtained for the most important characteristics of dislocations and their interaction with barriers.

Optimizing the Rolling Process of Lightweight Materials

Conventional rolling is a plastic deformation process that uses compression between two rolls to reduce material thickness and produce sheet/plane geometries. This deformation process modifies the material structure by generating texture, reducing the grain size, and strengthening the material. The rolling process can enhance the strength and hardness of lightweight materials while still preserving their inherent lightness. Lightweight metals like magnesium alloys tend to lack mechanical strength and hardness in load-bearing applications. The general rolling process is controlled by the thickness reduction, velocity of the rolls, and temperature. When held at a constant thickness reduction, each pass through the rolls introduces an increase in strain hardening, which could ultimately result in cracking, spallation, and other defects. This study is designed to optimize the rolling process by evaluating the effects of the strain rate, rather than the thickness reduction, as a process control parameter.

Effect of B2 nanoprecipitates on mechanical behavior of TiZrNbVAl lightweight high entropy alloys upon dynamic loading

The addition of B2 nanoprecipitates provides a new way to improve the mechanical properties of lightweight high entropy alloys (LHEAs) with body-centered-cubic (BCC) structure. However, the study of B2 nanoprecipitates on BCC-LHEAs is limited to quasi-static tension. In this work, TiZrNbVAl LHEAs with BCC structure was chosen as model alloys and the effect of B2 nanoprecipitates on dynamic mechanical properties of TiZrNbVAl LHEAs was studied. The results show that the introduction of B2 nanoprecipitates not only significantly improves the dynamic strength, but also increases the plasticity from 31 % to more than 46 %, with an increase of more than 48 %. Microstructure evolution proves that during the plastic deformation process, the B2 nanoprecipitates promoted a large number of “second-generation bands” of dislocation in the separation of the first-generation bands, which effectively extended the plastic deformation region to the entire sample and improved the uniform deformation ability of LHEAs. Our results provide a solution for improving the mechanical properties of LHEAs under dynamic/impact conditions.

FINITE ELEMENT ANALYSIS OF CHANGING OF STRESS CONDITION CAUSED BY DIAMOND BURNISHING

The article is aspected to the finite element modelling of stress in subsurface layer of aluminium alloy workpiece during diamond burnishing process. This cold forming process is a simple, cost-effective finishing method that can be used to improve surface integrity and provide compressive residual stress. Available with these, durability and quality enhancement of the components can be reached, but improperly chosen burnishing parameters can distort the efficiency of the plastic deformation process. In order to optimize this, a 2D FEM model is created including the real surface integrity of the workpiece which was measured with AltiSurf 520 surface roughness measuring device. The method is simulated using DEFORM-2D software, corresponding to the numerical values of burnishing parameters implemented in practice as well, thereby allowing a comparative analysis with the results of X-ray diffraction measurement.

Effects of homogenization temperature on microstructure, mechanical properties and corrosion behavior of binary Zn-Mn alloys extruded at different temperatures

In order to optimize the mechanical properties (MPs) of biodegradable Zn-based alloys, many researches have been conducted. However, the effect of homogenization treatment before the plastic deformation process on the MPs of biodegradable Zn-based alloys has not received sufficient attention, although it has been demonstrated to play an important role in improving the MPs of Al- and Mg-based alloys. In this work, as-cast Zn-0.8 wt% Mn alloys were firstly homogenized at two different temperatures (330 and 390 °C) followed by quenching and then extruded at three different temperatures (170, 230 and 300 °C). This work revealed the effects of homogenization temperature (HT) on microstructure, MPs and corrosion behavior of Zn-0.8 wt% Mn alloys extruded at different temperatures. The results showed that compared to the alloy homogenized at 330 °C (HT330), the alloy homogenized at 390 °C (HT390) has less precipitation of micron-sized MnZn13 particles in the homogenization process. During the subsequent extrusion processes at 170 and 230 °C, more submicron-sized MnZn13 particles are precipitated and finer Zn grains are formed in the HT390 alloys than in the HT330 alloys. Correspondingly, the two extruded HT390 alloys exhibit elongations of up to 133 % and 86 %, respectively, which are much higher than the 71 % and 65 % of the two extruded HT330 alloys. However, when the extruding temperature is elevated to 300 °C, high HT causes decrease in the fraction of both the micron- and submicron-sized MnZn13 particles as well as coarsening of Zn grains, followed by an increase in the strength of the as-extruded alloy. In addition, high HT is conductive to improving the corrosion resistance of the as-extruded alloys regardless of the extrusion temperature.

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.