Materials

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6 pages, 217 KiB

Open AccessEditorial

Hot Deformation and Microstructure Evolution of Metallic Materials

by Ivo Schindler

Materials 2023, 16(4), 1602; https://doi.org/10.3390/ma16041602 - 14 Feb 2023

Cited by 2 | Viewed by 1569

Abstract

Hot plastic deformation is a key method of processing metallic materials and controlling their final properties through structure-forming processes [...] Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

Research

Jump to: Editorial

23 pages, 16626 KiB

Open AccessArticle

Analysis of the Microstructure Development of Nb-Microalloyed Steel during Rolling on a Heavy-Section Mill

by Michal Sauer, Richard Fabík, Ivo Schindler, Petr Kawulok, Petr Opěla, Rostislav Kawulok, Vlastimil Vodárek and Stanislav Rusz

Materials 2023, 16(1), 288; https://doi.org/10.3390/ma16010288 - 28 Dec 2022

Cited by 3 | Viewed by 1692

Abstract

It is not realistic to optimize the roll pass design of profile rolling mills, which typically roll hundreds of profiles, using physical modelling or operational rolling. The use of reliable models of microstructure evolution is preferable here. Based on the mathematical equations describing [...] Read more.

It is not realistic to optimize the roll pass design of profile rolling mills, which typically roll hundreds of profiles, using physical modelling or operational rolling. The use of reliable models of microstructure evolution is preferable here. Based on the mathematical equations describing the microstructure evolution during hot rolling, a modified microstructure evolution model was presented that better accounts for the influence of strain-induced precipitation (SIP) on the kinetics of static recrystallization. The time required for half of the structure to soften, t_0.5, by static recrystallization was calculated separately for both situations in which strain-induced precipitation occurred or did not occur. On this basis, the resulting model was more sensitive to the description of grain coarsening in the high-rolling-temperature region, which is a consequence of the rapid progress of static recrystallization and the larger interpass times during rolling on cross-country and continuous mills. The modified model was verified using a plain strain compression test (PSCT) simulation of rolling a 100-mm-diameter round bar performed on the Hydrawedge II hot deformation simulator (HDS-20). Four variants of simulations were performed, differing in the rolling temperature in the last four passes. For comparison with the outputs of the modified model, an analysis of the austenite grain size after rolling was performed using optical metallography. For indirect comparison with the model outputs, the SIP initiation time was determined based on the NbX precipitate size distribution obtained by TEM. Using the PSCT and the outputs from the modified microstructure evolution model, it was found that during conventional rolling, strain-induced precipitation occurs after the last pass and thus does not affect the austenite grain size. By lowering the rolling temperature, it was possible to reduce the grain size by up to 56 μm, while increasing the mean flow stress by a maximum of 74%. The resulting grain size for all four modes was consistent with the operating results. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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14 pages, 3988 KiB

Open AccessArticle

Analysis of the Extrusion Process of Aluminium Alloy Profiles

by Teresa Bajor, Anna Kawałek, Szymon Berski, Henryk Jurczak and Jacek Borowski

Materials 2022, 15(23), 8311; https://doi.org/10.3390/ma15238311 - 23 Nov 2022

Cited by 4 | Viewed by 2362

Abstract

The paper presents an analysis of the results of numerical tests of the extrusion process of structural panels made of the 5xxx and 6xxx series aluminium alloys in a designed split die. The obtained products are intended for innovative superstructures of special car [...] Read more.

The paper presents an analysis of the results of numerical tests of the extrusion process of structural panels made of the 5xxx and 6xxx series aluminium alloys in a designed split die. The obtained products are intended for innovative superstructures of special car bodies. The main purpose of the research was the designed split die and numerical simulations and analysis of test results to determine the parameters of the extrusion process. The distribution of stress intensity, strain, strain rate, and temperature in the extruded metal was analysed for two different speeds of the punch movement. On the basis of the analysis of the distribution of stress values occurring in the extrusion process, the conditions enabling the real process of extrusion of the panel profile in industrial conditions in the designed split die were determined. It was shown that panel sections can be produced from ingots with a length of 770 mm on a press with a pressure of 35 MN (12”). Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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17 pages, 4469 KiB

Open AccessArticle

Hot Deformation Behavior of 4130 High-Strength Steel

by Aneta Łukaszek-Sołek, Tomasz Śleboda, Łukasz Lisiecki and Janusz Krawczyk

Materials 2022, 15(21), 7817; https://doi.org/10.3390/ma15217817 - 5 Nov 2022

Cited by 3 | Viewed by 1759

Abstract

Hot deformation behavior of 4130 steel and optimization of its processing parameters are presented in this paper. Compression tests were performed at temperatures ranging from 800 to 1200 °C and at the strain rates in the range from 0.01 to 100 s⁻¹ [...] Read more.

Hot deformation behavior of 4130 steel and optimization of its processing parameters are presented in this paper. Compression tests were performed at temperatures ranging from 800 to 1200 °C and at the strain rates in the range from 0.01 to 100 s⁻¹. A comprehensive analysis of the material behavior at different temperature and strain-rate ranges was performed taking into account various criteria of stability and instability of the material flow under various thermomechanical conditions. The flow–stress curves obtained during compression tests, as well as the processing maps elaborated on the basis of various flow–stability criteria, are discussed. Processing parameters developed according to the Prasad’s and Murty’s criteria are recommended for designing the technology of forging of the investigated steel. Such parameters ensure the homogeneity and stability of the material flow in a forged part, what was confirmed by successful forging of 4130 steel in industrial conditions. The processing map developed according to Gegel’s approach, as compared to the processing maps obtained in accordance with the Prasad’s and Murty’s criteria, should be treated as general support for determining the thermomechanical processing parameters. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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17 pages, 7097 KiB

Open AccessArticle

Modeling of the Closure of Metallurgical Defects in the Magnesium Alloy Die Forging Process

by Grzegorz Banaszek, Teresa Bajor, Anna Kawałek and Marcin Knapiński

Materials 2022, 15(21), 7465; https://doi.org/10.3390/ma15217465 - 25 Oct 2022

Cited by 7 | Viewed by 1465

Abstract

The article discusses the impact of hot forging elongation operations on the closure of metallurgical discontinuities such as middle porosity in selected magnesium alloys (AZ91) depending on the shape of the input used. Numerical modeling was carried out using the Forge^®NxT [...] Read more.

The article discusses the impact of hot forging elongation operations on the closure of metallurgical discontinuities such as middle porosity in selected magnesium alloys (AZ91) depending on the shape of the input used. Numerical modeling was carried out using the Forge^®NxT 2.1 program based on the finite element method and laboratory modeling in order to bring about the closure of defects of metallurgical origin in deformed forging ingots. On the basis of the conducted research, optimal values of the main technological parameters of forging and appropriate groups of anvils to be used in individual stages of forging were proposed in order to eliminate metallurgical defects. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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22 pages, 7635 KiB

Open AccessArticle

The Influence of Ce, La, and SiC Particles Addition on the Formability of an Al-Si-Cu-Mg-Fe SiCp-MMC

by Andong Du, Lucia Lattanzi, Anders E. W. Jarfors, Jie Zhou, Jinchuan Zheng, Kaikun Wang and Gegang Yu

Materials 2022, 15(11), 3789; https://doi.org/10.3390/ma15113789 - 26 May 2022

Cited by 7 | Viewed by 2110

Abstract

Road transport and the associated fuel consumption plays a primary role in emissions. Weight reduction is critical to reaching the targeted reduction of 34% in 2025. Weight reduction in moving parts, such as pistons and brake disc rotors, provide a high-impact route to [...] Read more.

Road transport and the associated fuel consumption plays a primary role in emissions. Weight reduction is critical to reaching the targeted reduction of 34% in 2025. Weight reduction in moving parts, such as pistons and brake disc rotors, provide a high-impact route to achieve this goal. The current study aims to investigate the formability of Al–Si alloys reinforced with different fractions and different sizes of SiCp to create an efficient and lightweight Al-MMC brake disk. Lanthanum (La) and cerium (Ce) were added to strengthen the aluminium matrix alloy and to improve the capability of the Al-MMC brake discs to withstand elevated temperature conditions, such as more extended braking periods. La and Ce formed intermetallic phases that further strengthened the composite. The analysis showed the processability and thermal stability of the different material’s combinations: increased particle sizes and broader size range mixture supported the formation of the SiCp particle interactions, acting as an internal scaffolding. In conclusion, the additions of Ce and La strengthened the softer matrix regions and resulted in a doubled compression peak strength of the material without affecting the formability, as demonstrated by the processing maps. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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15 pages, 43787 KiB

Open AccessArticle

Microstructure and Texture Evolution in Low Carbon and Low Alloy Steel during Warm Deformation

by Sheng Xu, Haijie Xu, Xuedao Shu, Shuxin Li and Zhongliang Shen

Materials 2022, 15(7), 2702; https://doi.org/10.3390/ma15072702 - 6 Apr 2022

Cited by 2 | Viewed by 2416

Abstract

Warm compression tests were carried out on low carbon and low alloy steel at temperatures of 600–850 °C and stain rates of 0.01–10 s⁻¹. The evolution of microstructure and texture was studied using a scanning electron microscope and electron backscattered diffraction. [...] Read more.

Warm compression tests were carried out on low carbon and low alloy steel at temperatures of 600–850 °C and stain rates of 0.01–10 s⁻¹. The evolution of microstructure and texture was studied using a scanning electron microscope and electron backscattered diffraction. The results indicated that cementite spheroidization occurred and greatly reduced at 750 °C due to a phase transformation. Dynamic recrystallization led to a transition from {112}<110> texture to {111}<112> texture. Below 800 °C, the intensity and variation of texture with deformation temperature is more significant than that above 800 °C. The contents of the {111}<110> texture and {111}<112> texture were equivalent above 800 °C, resulting in the better uniformity of γ-fiber texture. Nucleation of <110>//ND-oriented grains increased, leading to the strengthening of <110>//ND texture. Microstructure analysis revealed that the uniform and refined grains can be obtained after deformation at 800 °C and 850 °C. The texture variation reflected the fact that 800 °C was the critical value for temperature sensitivity of warm deformation. At a large strain rate, the lowest dislocation density appeared after deformation at 800 °C. Therefore, 800 °C is a suitable temperature for the warm forming application, where the investigated material is easy to deform and evolves into a uniform and refined microstructure. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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16 pages, 14243 KiB

Open AccessArticle

Effect of Dynamic Recrystallization on Microstructural Evolution in B Steels Microalloyed with Nb and/or Mo

by Irati Zurutuza, Nerea Isasti, Eric Detemple, Volker Schwinn, Hardy Mohrbacher and Pello Uranga

Materials 2022, 15(4), 1424; https://doi.org/10.3390/ma15041424 - 15 Feb 2022

Cited by 3 | Viewed by 2296

Abstract

The dynamic recrystallization behavior of ultra-high strength boron-microalloyed steels optionally alloyed with niobium and molybdenum is analyzed in this paper. Multipass torsion tests were performed to simulate plate rolling conditions followed by direct quenching. The influence of alloy composition on the transformed microstructure [...] Read more.

The dynamic recrystallization behavior of ultra-high strength boron-microalloyed steels optionally alloyed with niobium and molybdenum is analyzed in this paper. Multipass torsion tests were performed to simulate plate rolling conditions followed by direct quenching. The influence of alloy composition on the transformed microstructure was evaluated by means of EBSD, thereby characterizing the morphology of the austenite grain morphology after roughing and finishing passes. The results indicated that for Nb-microalloyed steel, partial dynamic recrystallization occurred and resulted in local clusters of fine-sized equiaxed grains dispersed within the pancaked austenitic structure. A recrystallized austenite fraction appeared and transformed into softer phase constituents after direct quenching. The addition of Mo was shown to be an effective means of suppressing dynamic recrystallization. This effect of molybdenum in addition to its established hardenability effects hence safeguards the formation of fully martensitic microstructures, particularly in direct quenching processes. Additionally, the circumstances initiating dynamic recrystallization were studied in more detail, and the interference of the various alloying elements with the observed phenomena and the potential consequences of dynamic recrystallization before quenching are discussed. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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26 pages, 75734 KiB

Open AccessArticle

Hot Deformation Behavior of Non-Alloyed Carbon Steels

by Petr Kawulok, Petr Opěla, Ivo Schindler, Rostislav Kawulok, Stanislav Rusz, Michal Sauer and Kateřina Konečná

Materials 2022, 15(2), 595; https://doi.org/10.3390/ma15020595 - 13 Jan 2022

Cited by 6 | Viewed by 1783

Abstract

The hot deformation behavior of selected non-alloyed carbon steels was investigated by isothermal continuous uniaxial compression tests. Based on the analysis of experimentally determined flow stress curves, material constants suitable for predicting peak flow stress σ_p, peak strain ε_p and [...] Read more.

The hot deformation behavior of selected non-alloyed carbon steels was investigated by isothermal continuous uniaxial compression tests. Based on the analysis of experimentally determined flow stress curves, material constants suitable for predicting peak flow stress σ_p, peak strain ε_p and critical strain ε_crDRX necessary to induce dynamic recrystallization and the corresponding critical flow stresses σ_crDRX were determined. The validity of the predicted critical strains ε_crDRX was then experimentally verified. Fine dynamically recrystallized grains, which formed at the boundaries of the original austenitic grains, were detected in the microstructure of additionally deformed specimens from low-carbon investigated steels. Furthermore, equations describing with perfect accuracy a simple linear dependence of the critical strain ε_crDRX on peak strain ε_p were derived for all investigated steels. The determined hot deformation activation energy Q decreased with increasing carbon content (also with increasing carbon equivalent value) in all investigated steels. A logarithmic equation described this dependency with reasonable accuracy. Individual flow stress curves of the investigated steels were mathematically described using the Cingara and McQueen model, while the predicted flow stresses showed excellent accuracy, especially in the strains ranging from 0 to ε_p. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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25 pages, 4924 KiB

Open AccessEditor’s ChoiceArticle

Developments towards a Multiscale Meshless Rolling Simulation System

by Umut Hanoglu and Božidar Šarler

Materials 2021, 14(15), 4277; https://doi.org/10.3390/ma14154277 - 30 Jul 2021

Cited by 5 | Viewed by 1908

Abstract

The purpose of the present paper is to predict the grain size of steel during the hot-rolling process. The basis represents a macroscopic simulation system that can cope with temperatures, stresses and strains of steel in a complete continuous rolling mill, including reversible [...] Read more.

The purpose of the present paper is to predict the grain size of steel during the hot-rolling process. The basis represents a macroscopic simulation system that can cope with temperatures, stresses and strains of steel in a complete continuous rolling mill, including reversible pre-rolling and finishing rolling with several tenths of rolling passes. The grain size models, newly introduced in the present paper, are one-way coupled to the macro-scale calculations performed with the slice model assumption. Macroscale solution is based on a novel radial basis function collocation method. This numerical method is truly meshless by involving the space discretization in arbitrarily distributed nodes without meshing. A new efficient node generation algorithm is implemented in the present paper and demonstrated for irregular domains of the slice as they appear in different rolling passes. Multiple grain size prediction models are considered. Grain size prediction models are based on empirical relations. Austenite grain size at each rolling pass as well as the ferrite grain size at the end of rolling are predicted in this simulation. It is also shown that based on the rolling schedule, it is highly likely that recrystallization takes place at each pass throughout a continuous rolling mill. The simulation system is coded as a user-friendly computer application for industrial use based on programming language C# and an open source developer platform NET and runs on regular personal computers the computational time for a typical rolling simulation is usually less than one hour and can thus be straightforwardly used to optimize the rolling mill design in a reasonable time. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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17 pages, 5265 KiB

Open AccessArticle

Investigation of the Influence of Open-Die Forging Parameters on the Flow Kinetics of AZ91 Magnesium Alloy

by Grzegorz Banaszek, Teresa Bajor, Anna Kawałek and Tomasz Garstka

Materials 2021, 14(14), 4010; https://doi.org/10.3390/ma14144010 - 17 Jul 2021

Cited by 5 | Viewed by 2515

Abstract

This paper presents the results of numerical tests of the process of forging magnesium alloy ingots (AZ91) on a hydraulic press with the use of flat and proprietary shaped anvils. The analysis of the hydrostatic pressure distribution and the deformation intensity was carried [...] Read more.

This paper presents the results of numerical tests of the process of forging magnesium alloy ingots (AZ91) on a hydraulic press with the use of flat and proprietary shaped anvils. The analysis of the hydrostatic pressure distribution and the deformation intensity was carried out. It is one of the elements used for determining the assumptions for the technology of forging to obtain a semi-finished product from the AZ91 alloy with good strength properties. The aim of the research was to reduce the number of forging passes, which will shorten the operation time and reduce the product manufacturing costs. Numerical tests of the AZ91 magnesium alloy were carried out using commercial Forge^®NxT software. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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12 pages, 4301 KiB

Open AccessArticle

Microstructure Evolution during Hot Deformation of UNS S32750 Super-Duplex Stainless Steel Alloy

by Elisabeta Mirela Cojocaru, Anna Nocivin, Doina Răducanu, Mariana Lucia Angelescu, Ion Cinca, Irina Varvara Balkan, Nicolae Șerban and Vasile Dănuț Cojocaru

Materials 2021, 14(14), 3916; https://doi.org/10.3390/ma14143916 - 14 Jul 2021

Cited by 3 | Viewed by 2422

Abstract

The present paper analyzes UNS S32750 Super-Duplex Stainless Steel hot deformation behavior during processing by upsetting. The objective of this paper is to determine the optimum range of deformation temperatures, considering that both austenite and ferrite have different deformation behaviors due to their [...] Read more.

The present paper analyzes UNS S32750 Super-Duplex Stainless Steel hot deformation behavior during processing by upsetting. The objective of this paper is to determine the optimum range of deformation temperatures, considering that both austenite and ferrite have different deformation behaviors due to their different morphology, physical, and mechanical properties. Because the capability of plastic deformation accommodation of ferrite is reduced when compared to austenite, side cracks and fissures can form during the hot deformation process. Consequently, it is important to find the optimum conditions of deformation of this type of stainless steel to establish the best processing parameters without deteriorating the material. The experimental program involved the application of hot deformation by the upsetting method on a series of samples between 1000 °C and 1275 °C, with a total degree of deformation of 30%. The resultant samples were examined by SEM-EBSD to establish and analyze the evolution of the phases present in the structure from several points of view: nature, distribution, morphology (size and shape), and their structural homogeneity. The GROD (Grain Reference Orientation Deviation) distribution map was also determined while taking into account the possible precipitation of the secondary austenite phase (γ₂-phase) and the analysis of the dynamic recrystallization process according to the applied deformation temperature. The main conclusion was that UNS S32750 SDSS steel can be safely deformed by upsetting between 1050–1275 °C, with an experimented total degree of deformation of 30%. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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14 pages, 5694 KiB

Open AccessArticle

A Comparative Study on the Hot Deformation Behavior of As-Cast and Twin-Roll Cast Mg-6.8Y-2.5Zn-0.4Zr Alloy

by Kristina Kittner, Madlen Ullmann and Ulrich Prahl

Materials 2021, 14(13), 3628; https://doi.org/10.3390/ma14133628 - 29 Jun 2021

Cited by 5 | Viewed by 2106

Abstract

The Mg-6.8Y-2.5Zn-0.4Zr (WZ73) alloy exhibits different microstructure characteristic after conventional casting compared to the twin-roll cast (TRC) state. Twin-roll casting results in a finer microstructure, where the LPSO phases are more finely distributed and less strongly connected. A transfer of the hot deformation [...] Read more.

The Mg-6.8Y-2.5Zn-0.4Zr (WZ73) alloy exhibits different microstructure characteristic after conventional casting compared to the twin-roll cast (TRC) state. Twin-roll casting results in a finer microstructure, where the LPSO phases are more finely distributed and less strongly connected. A transfer of the hot deformation behavior from the as-cast condition to the TRC condition is only possible to a limited extent due to the microstructural differences. Both states show differences in the recrystallization behavior during hot deformation. In the conventional cast state, dynamic recrystallization (DRX) is assumed to be delayed by the occurrence of coarse blocky LPSO phases. Main DRX mechanisms are continuous dynamic recrystallization (CDRX), particle stimulated nucleation (PSN) and twin induced dynamic recrystallization (TDRX). The deformed TRC sample showed pronounced DRX at almost all deformation conditions. Besides the TDRX and the PSN mechanism, kink induced dynamic recrystallization (KDRX) can be observed. Optimum deformation conditions for both states are temperatures from 500 °C to 520 °C, and strain rates ranging from 0.01 s⁻¹ to 0.1 s⁻¹ for the as-cast material as well as a strain rate of 1 s⁻¹ for the TRC material. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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17 pages, 27769 KiB

Open AccessEditor’s ChoiceArticle

Bonding of Al6061 by Hot Compression Forming: A Computational and Experimental Study of Interface Conditions at Bonded Surfaces

by Brigit Mittelman, Michael Ben-Haroush, Ira Aloush, Linoy Mordechay and Elad Priel

Materials 2021, 14(13), 3598; https://doi.org/10.3390/ma14133598 - 28 Jun 2021

Cited by 2 | Viewed by 2135

Abstract

In recent years, there has been a growing interest in composite components, which may be designed to provide enhanced mechanical and physical effective properties. One of the methods available to produce such components is joining by plastic deformation, which results in metallurgical bonding [...] Read more.

In recent years, there has been a growing interest in composite components, which may be designed to provide enhanced mechanical and physical effective properties. One of the methods available to produce such components is joining by plastic deformation, which results in metallurgical bonding at the interface. However, the portions of the interface that are bonded and the inhomogeneity in the bonding strength achieved at the interface tend to be overlooked. In the present study, Al6061 beams were bonded, by hot compression (300–500 °C) to different degrees of reduction. The compression was followed by tensile debonding experiments and the revealed interface was microscopically characterized in order to determine the areas that were metallurgically bonded. The SEM characterization revealed that the actual bonded area is much smaller than the interface contact area. Thermo-mechanical finite element models of the compression stage were used to investigate the thermo-mechanical fields, which develop along the interface and influence the resulting bonding strength. The principal strain field patterns across the interface area were shown to be similar to the experimentally observed temperature-dependent bonding patterns. In addition, a quantitative criterion for bonding quality was implemented and shown to correlate with the experimental findings. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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21 pages, 16591 KiB

Open AccessEditor’s ChoiceArticle

Multi-Scale Modeling of Microstructure Evolution during Multi-Pass Hot-Rolling and Cooling Process

by Xian Lin, Xinyi Zou, Dong An, Bruce W. Krakauer and Mingfang Zhu

Materials 2021, 14(11), 2947; https://doi.org/10.3390/ma14112947 - 29 May 2021

Cited by 12 | Viewed by 3091

Abstract

In this work, a 6-pass hot-rolling process followed by air cooling is studied by means of a coupled multi-scale simulation approach. The finite element method (FEM) is utilized to obtain macroscale thermomechanical parameters including temperature and strain rate. The microstructure evolution during the [...] Read more.

In this work, a 6-pass hot-rolling process followed by air cooling is studied by means of a coupled multi-scale simulation approach. The finite element method (FEM) is utilized to obtain macroscale thermomechanical parameters including temperature and strain rate. The microstructure evolution during the recrystallization and austenite (γ) to ferrite (α) transformation is simulated by a mesoscale cellular automaton (CA) model. The solute drag effect is included in the CA model to take into account the influence of manganese on the γ/α interface migration. The driving force for α-phase nucleation and growth also involves the contribution of the deformation stored energy inherited from hot-rolling. The simulation renders a clear visualization of the evolving grain structure during a multi-pass hot-rolling process. The variations of the nonuniform, deformation-stored energy field and carbon concentration field are also reproduced. A detailed analysis demonstrates how the parameters, including strain rate, grain size, temperature, and inter-pass time, influence the different mechanisms of recrystallization. Grain refinement induced by recrystallization and the γ→α phase transformation is also quantified. The simulated final α-fraction and the average α-grain size agree reasonably well with the experimental microstructure. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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25 pages, 15469 KiB

Open AccessArticle

The Analysis of Deformability, Structure and Properties of AZ61 Cast Magnesium Alloy in a New Hammer Forging Process for Aircraft Mounts

by Anna Dziubińska, Piotr Surdacki and Krzysztof Majerski

Materials 2021, 14(10), 2593; https://doi.org/10.3390/ma14102593 - 16 May 2021

Cited by 9 | Viewed by 2467

Abstract

This article presents the analysis of the deformability, structure and properties of the AZ61 cast magnesium alloy on the example of a new forging process of aircraft mount forgings. It was assumed that their production process would be based on drop forging on [...] Read more.

This article presents the analysis of the deformability, structure and properties of the AZ61 cast magnesium alloy on the example of a new forging process of aircraft mount forgings. It was assumed that their production process would be based on drop forging on a die hammer. Two geometries of preforms, differing in forging degree, were used as the billet for the forging process. It was assumed that using a cast, unformed preform positively affects the deformability of hard-deformable magnesium alloys and flow kinematics during their forging and reduces the number of operations necessary to obtain the correct product. Numerical analysis of the proposed new technology was carried out using DEFORM 3D v.11, a commercial program dedicated to analyzing metal forming processes. The simulations were performed in the conditions of spatial strain, considering the full thermomechanical analysis. The obtained results of numerical tests confirmed the possibility of forming the forgings of aviation mounts from the AZ61 cast magnesium alloy with the proposed technology. They also allowed us to obtain information about the kinematics of the material flow during forming and process parameters, such as strain intensity distribution, temperatures, Cockcroft–Latham criterion and forming energy. The proposed forging process on a die hammer was verified in industrial conditions. The manufactured forgings of aircraft mounts made of AZ61 magnesium alloy were subjected to qualitative tests in terms of their structure, conductivity and mechanical properties. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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18 pages, 21456 KiB

Open AccessArticle

Study on the Dynamic Recrystallization Behavior of 47Zr-45Ti-5Al-3V Alloy by CA–FE Simulation

by Wenwei Zhang, Qiuyue Yang, Yuanbiao Tan, Ya Yang, Song Xiang and Fei Zhao

Materials 2021, 14(10), 2562; https://doi.org/10.3390/ma14102562 - 14 May 2021

Cited by 4 | Viewed by 1883

Abstract

The dynamic recrystallization (DRX) behavior of 47Zr-45Ti-5Al-3V alloy was studied by using the experiment and numerical simulation method based on DEFORM-3D software and cellular automata (CA) over a range of deformation temperatures (850 to 1050 °C) and strain rates (10⁻³ to 10 [...] Read more.

The dynamic recrystallization (DRX) behavior of 47Zr-45Ti-5Al-3V alloy was studied by using the experiment and numerical simulation method based on DEFORM-3D software and cellular automata (CA) over a range of deformation temperatures (850 to 1050 °C) and strain rates (10⁻³ to 10⁰ s⁻¹). The results reveal that the DRX behavior of 47Zr-45Ti-5Al-3V alloy strongly depends on hot-working parameters. With rising deformation temperature (T) and decreasing strain rate (

\dot{ε}

), the grain size (

d_{D R X}

) and volume fraction (

X_{D R X}

) of DRX dramatically boost. The kinetics models of the

d_{D R X}

and

X_{D R X}

of DRX grains were established. According to the developed kinetics models for DRX of 47Zr-45Ti-5Al-3V alloy, the distributions of the

d_{D R X}

and

X_{D R X}

for DRX grains were predicted by DEFORM-3D. DRX microstructure evolution is simulated by CA. The correlation of the kinetics model is verified by comparing the

d_{D R X}

and

X_{D R X}

between the experimental and finite element simulation (FEM) results. The nucleation and growth of dynamic recrystallization grains in 47Zr-45Ti-5Al-3V alloy during hot-working can be simulated accurately by CA simulation, comparing with FEM. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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11 pages, 2879 KiB

Open AccessArticle

Investigation of Forging Metal Specimens of Different Relative Reductions Using Ultrasonic Waves

by Ján Moravec, Peter Bury and František Černobila

Materials 2021, 14(9), 2406; https://doi.org/10.3390/ma14092406 - 5 May 2021

Cited by 6 | Viewed by 1999

Abstract

Forgings produced in industry are an irreplaceable basis for subsequent elaborating on machine tools. The quality of the semi-finished product produced by forging is a necessary prerequisite for ensuring the final quality of the final product because the forging can produce some defects. [...] Read more.

Forgings produced in industry are an irreplaceable basis for subsequent elaborating on machine tools. The quality of the semi-finished product produced by forging is a necessary prerequisite for ensuring the final quality of the final product because the forging can produce some defects. The presented paper is aimed at investigation of selected characteristics of forging steel specimens for various levels of their relative reduction. Ultrasound testing belongs to methods for investigation of structure changes, including defects. Experimental investigation, using both the attenuation and velocity measurements, verify that the reduction of specimens’ material can have an effect on the propagation of ultrasound waves passing through the specimen body. The procedure of steel samples forging corresponds accordingly to the process of their hardening. The increase of toughness after relative reduction of forging in the range of 10–50% is with highest probability caused by the strength matrices development due to the relatively important deformation hardening. It is evident that the deformation hardening is almost the same after every 10% addition of relative reduction. Experiments are supplemented by Barkhausen noise detection and metallographic characteristics of the samples. While differences between the Barkhausen noise values are in principle relatively small and significant differences are only in the values of the position of the envelope, there is maximum coincidence with ultrasonic investigation. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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15 pages, 5553 KiB

Open AccessArticle

Application of the Strain Compensation Model and Processing Maps for Description of Hot Deformation Behavior of Metastable β Titanium Alloy

by Oleksandr Lypchanskyi, Tomasz Śleboda, Aneta Łukaszek-Sołek, Krystian Zyguła and Marek Wojtaszek

Materials 2021, 14(8), 2021; https://doi.org/10.3390/ma14082021 - 17 Apr 2021

Cited by 16 | Viewed by 2604

Abstract

The flow behavior of metastable β titanium alloy was investigated basing on isothermal hot compression tests performed on Gleeble 3800 thermomechanical simulator at near and above β transus temperatures. The flow stress curves were obtained for deformation temperature range of 800–1100 °C and [...] Read more.

The flow behavior of metastable β titanium alloy was investigated basing on isothermal hot compression tests performed on Gleeble 3800 thermomechanical simulator at near and above β transus temperatures. The flow stress curves were obtained for deformation temperature range of 800–1100 °C and strain rate range of 0.01–100 s⁻¹. The strain compensated constitutive model was developed using the Arrhenius-type equation. The high correlation coefficient (R) as well as low average absolute relative error (AARE) between the experimental and the calculated data confirmed a high accuracy of the developed model. The dynamic material modeling in combination with the Prasad stability criterion made it possible to generate processing maps for the investigated processing temperature, strain and strain rate ranges. The high material flow stability under investigated deformation conditions was revealed. The microstructural analysis provided additional information regarding the flow behavior and predominant deformation mechanism. It was found that dynamic recovery (DRV) was the main mechanism operating during the deformation of the investigated β titanium alloy. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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22 pages, 13271 KiB

Open AccessArticle

Shaping Microstructure and Mechanical Properties of High-Carbon Bainitic Steel in Hot-Rolling and Long-Term Low-Temperature Annealing

by Tomasz Dembiczak and Marcin Knapiński

Materials 2021, 14(2), 384; https://doi.org/10.3390/ma14020384 - 14 Jan 2021

Cited by 2 | Viewed by 1934

Abstract

Based on the research results, coefficients in constitutive equations, describing the kinetics of dynamic, meta-dynamic, and static recrystallization in high-carbon bainitic steel during hot deformation were determined. The developed mathematical model takes into account the dependence of the changing kinetics in the structural [...] Read more.

Based on the research results, coefficients in constitutive equations, describing the kinetics of dynamic, meta-dynamic, and static recrystallization in high-carbon bainitic steel during hot deformation were determined. The developed mathematical model takes into account the dependence of the changing kinetics in the structural size of the preliminary austenite grains, the value of strain, strain rate, temperature, and time. Physical simulations were carried out on rectangular specimens. Compression tests with a flat state of deformation were carried out using a Gleeble 3800. Based on dilatometric studies, coefficients were determined in constitutive equations, describing the grain growth of the austenite of high-carbon bainite steel under isothermal annealing conditions. The aim of the research was to verify the developed mathematical models in semi-industrial conditions during the hot-rolling process of high-carbon bainite steel. Analysis of the semi-industrial studies of the hot-rolling and long-term annealing process confirmed the correctness of the predicted mathematical models describing the microstructure evolution. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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13 pages, 14161 KiB

Open AccessArticle

A Flow Stress Model of 300M Steel for Isothermal Tension

by Rongchuang Chen, Shiyang Zhang, Xianlong Liu and Fei Feng

Materials 2021, 14(2), 252; https://doi.org/10.3390/ma14020252 - 7 Jan 2021

Cited by 12 | Viewed by 3852

Abstract

To investigate the effect of hot working parameters on the flow behavior of 300M steel under tension, hot uniaxial tensile tests were implemented under different temperatures (950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C) and strain rates (0.01 s⁻¹, [...] Read more.

To investigate the effect of hot working parameters on the flow behavior of 300M steel under tension, hot uniaxial tensile tests were implemented under different temperatures (950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C) and strain rates (0.01 s⁻¹, 0.1 s⁻¹, 1 s⁻¹, 10 s⁻¹). Compared with uniaxial compression, the tensile flow stress was 29.1% higher because dynamic recrystallization softening was less sufficient in the tensile stress state. The ultimate elongation of 300M steel increased with the decrease of temperature and the increase of strain rate. To eliminate the influence of sample necking on stress-strain relationship, both the stress and the strain were calibrated using the cross-sectional area of the neck zone. A constitutive model for tensile deformation was established based on the modified Arrhenius model, in which the model parameters (n, α, Q, ln(A)) were described as a function of strain. The average deviation was 6.81 MPa (6.23%), showing good accuracy of the constitutive model. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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20 pages, 4719 KiB

Open AccessEditor’s ChoiceArticle

Deformation Characteristics and Constitutive Equations for the Semi-Solid Isothermal Compression of Cold Radial Forged 6063 Aluminium Alloy

by Yongfei Wang, Shengdun Zhao, Yi Guo, Kuanxin Liu and Shunqi Zheng

Materials 2021, 14(1), 194; https://doi.org/10.3390/ma14010194 - 3 Jan 2021

Cited by 10 | Viewed by 2601

Abstract

Al-Mg-Si based alloys are popular alloys used in the automotive industry. However, limited studies have been performed to investigate the microstructure, deformation characteristics, and deformation mechanism for the semi-solid 6063 alloys. In this study, the cold radial forging method and semi-solid isothermal treatment [...] Read more.

Al-Mg-Si based alloys are popular alloys used in the automotive industry. However, limited studies have been performed to investigate the microstructure, deformation characteristics, and deformation mechanism for the semi-solid 6063 alloys. In this study, the cold radial forging method and semi-solid isothermal treatment (SSIT) are proposed in the semi-solid isothermal compression (SSIC) process to fabricate high-quality semi-solid 6063 billets. The effects of deformation temperature, strain rate, and strain on the microstructure, deformation characteristics, and deformation mechanism of the SSIC of cold radial forged 6063 alloys were investigated experimentally. Constitutive equations were established based on the measured data in experiments to predict the flow stress. Results show that an average grain size in the range from 59.22 to 73.02 μm and an average shape factor in the range from 071 to 078 can be obtained in the microstructure after the cold radial forged 6063 alloys were treated with SSIT process. Four stages (i.e., sharp increase, decrease, steady state, and slow increase) were observed in the true stress- true strain curve. The correlation coefficient of the constitutive equation was obtained as 0.9796 while the average relative error was 5.01%. The deformation mechanism for SSIC of cold radial forged aluminum alloy 6063 mainly included four modes: The liquid phase flow, grain slide or grain rotation along with the liquid film, slide among solid grains, and the plastic deformation of solid grains. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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16 pages, 67913 KiB

Open AccessArticle

Superplastic Deformation of Al–Cu Alloys after Grain Refinement by Extrusion Combined with Reversible Torsion

by Kinga Rodak, Dariusz Kuc and Tomasz Mikuszewski

Materials 2020, 13(24), 5803; https://doi.org/10.3390/ma13245803 - 18 Dec 2020

Cited by 5 | Viewed by 2051

Abstract

The binary as-cast Al–Cu alloys Al-5%Cu, Al-25%Cu, and Al-33%Cu (in wt %), composed of the intermetallic θ-Al₂Cu and α-Al phases, were prepared from pure components and were subsequently severely plastically deformed by extrusion combined with reversible torsion (KoBo) to refinement of [...] Read more.

The binary as-cast Al–Cu alloys Al-5%Cu, Al-25%Cu, and Al-33%Cu (in wt %), composed of the intermetallic θ-Al₂Cu and α-Al phases, were prepared from pure components and were subsequently severely plastically deformed by extrusion combined with reversible torsion (KoBo) to refinement of α-Al and Al₂Cu phases. The extrusion combined with reversible torsion was carried out using extrusion coefficients of λ = 30 and λ = 98. KoBo applied to the Al–Cu alloys with different initial structures (differences in fraction and phase size) allowed us to obtain for alloys (Al-25%Cu and Al-33%Cu), with higher value of intermetallic phase, large elongations in the range of 830–1100% after tensile tests at the temperature of 400 °C with the strain rate of 10⁻⁴ s⁻¹. The value of elongation depended on extrusion coefficient and increase, with λ increasing as a result of α-Al and Al₂Cu phase refinement to about 200–400 nm. Deformation at the temperature of 300 °C, independently of the extrusion coefficient (λ), did not ensure superplastic properties of the analyzed alloys. A microstructural study showed that the mechanism of grain boundary sliding was responsible for superplastic deformation. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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20 pages, 10478 KiB

Open AccessArticle

Effects of Austenitization Temperature and Pre-Deformation on CCT Diagrams of 23MnNiCrMo5-3 Steel

by Ivo Schindler, Rostislav Kawulok, Petr Opěla, Petr Kawulok, Stanislav Rusz, Jaroslav Sojka, Michal Sauer, Horymír Navrátil and Lukáš Pindor

Materials 2020, 13(22), 5116; https://doi.org/10.3390/ma13225116 - 13 Nov 2020

Cited by 5 | Viewed by 2261

Abstract

The combined effect of deformation temperature and strain value on the continuous cooling transformation (CCT) diagram of low-alloy steel with 0.23% C, 1.17% Mn, 0.79% Ni, 0.44% Cr, and 0.22% Mo was studied. The deformation temperature (identical to the austenitization temperature) was in [...] Read more.

The combined effect of deformation temperature and strain value on the continuous cooling transformation (CCT) diagram of low-alloy steel with 0.23% C, 1.17% Mn, 0.79% Ni, 0.44% Cr, and 0.22% Mo was studied. The deformation temperature (identical to the austenitization temperature) was in the range suitable for the wire rolling mill. The applied compressive deformation corresponded to the true strain values in an unusually wide range. Based on the dilatometric tests and metallographic analyses, a total of five different CCT diagrams were constructed. Pre-deformation corresponding to the true strain of 0.35 or even 1.0 had no clear effect on the austenite decomposition kinetics at the austenitization temperature of 880 °C. During the long-lasting cooling, recrystallization and probably coarsening of the new austenitic grains occurred, which almost eliminated the influence of pre-deformation on the temperatures of the diffusion-controlled phase transformations. Decreasing the deformation temperature to 830 °C led to the significant acceleration of the austenite → ferrite and austenite → pearlite transformations due to the applied strain of 1.0 only in the region of the cooling rate between 3 and 35 °C·s⁻¹. The kinetics of the bainitic or martensitic transformation remained practically unaffected by the pre-deformation. The acceleration of the diffusion-controlled phase transformations resulted from the formation of an austenitic microstructure with a mean grain size of about 4 µm. As the analysis of the stress–strain curves showed, the grain refinement was carried out by dynamic and metadynamic recrystallization. At low cooling rates, the effect of plastic deformation on the kinetics of phase transformations was indistinct. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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19 pages, 6822 KiB

Open AccessArticle

Correlation among the Power Dissipation Efficiency, Flow Stress Course, and Activation Energy Evolution in Cr-Mo Low-Alloyed Steel

by Petr Opěla, Ivo Schindler, Petr Kawulok, Rostislav Kawulok, Stanislav Rusz, Horymír Navrátil and Radek Jurča

Materials 2020, 13(16), 3480; https://doi.org/10.3390/ma13163480 - 7 Aug 2020

Cited by 14 | Viewed by 2178

Abstract

In the presented research, conventional hot processing maps superimposed over the flow stress maps or activation energy maps are utilized to study a correlation among the efficiency of power dissipation, flow stress, and activation energy evolution in the case of Cr-Mo low-alloyed steel. [...] Read more.

In the presented research, conventional hot processing maps superimposed over the flow stress maps or activation energy maps are utilized to study a correlation among the efficiency of power dissipation, flow stress, and activation energy evolution in the case of Cr-Mo low-alloyed steel. All maps have been assembled on the basis of two flow curve datasets. The experimental one is the result of series of uniaxial hot compression tests. The predicted one has been calculated on the basis of the subsequent approximation procedure via a well-adapted artificial neural network. It was found that both flow stress and activation energy evolution are capable of expressing changes in the studied steel caused by the hot compression deformation. A direct association with the course of power dissipation efficiency is then evident in the case of both. The connection of the presence of instability districts to the activation energy evolution, flow stress course, and power dissipation efficiency was discussed further. Based on the obtained findings it can be stated that the activation energy processing maps represent another tool for the finding of appropriate forming conditions and can be utilized as a support feature for the conventionally-used processing maps to extend their informative ability. Full article

(This article belongs to the Special Issue Hot Deformation and Microstructure Evolution of Metallic Materials)

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