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Forging Processes of Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (30 November 2020) | Viewed by 50561

Special Issue Editor

Prof. Dr. Andrzej Gontarz

E-Mail Website
Guest Editor
Lublin University of Technology, Lublin, Poland
Interests: theory and technology of metal forming processes; forging processes; innovative metal forming processes; aluminium alloy; magnesium alloy; titanium alloy; steel; FEM
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The forging of metals and alloys is one of the oldest metal forming techniques used by humankind. Forging processes were improved over the centuries and are still being refined. Today, we are certain that there is no limit to these improvements and that we will never reach the point when we can say that nothing more is to be done. Despite the enormous knowledge and experience gained over the centuries, we still face new challenges arising from civilizational progress. One of them is the necessity to produce parts that are more and more complex in terms of shape and properties, which requires not only a deep insight into phenomena that accompany forging processes, but also the development of new techniques, machines and equipment, materials, research methods, and tools, as well as the improvement of the existing ones. With the Special Issue on “Forging Processes of Materials”, the Editorial Board of Materials offers authors the possibility of presenting their findings in this field. As the Guest Editor for the Special Issue, I would like to invite you to contribute to this publication, which, I hope, will serve as a source of knowledge for both theoreticians and practitioners. Hence, I encourage authors to submit papers exploring, in a broad sense, the theory and practice of forging metals and alloys. I wish to assure you that we will make every effort to ensure the highest quality of this Special Issue.

Prof. Dr. Andrzej Gontarz
Guest Editor

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Keywords

  • hot forging
  • cold forging
  • technology
  • theory
  • machines and equipment

Published Papers (22 papers)

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Research

14 pages, 4405 KiB  
Article
Challenges in the Forging of Steel-Aluminum Bearing Bushings
by Bernd-Arno Behrens, Johanna Uhe, Tom Petersen, Christian Klose, Susanne E. Thürer, Julian Diefenbach and Anna Chugreeva
Materials 2021, 14(4), 803; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14040803 - 08 Feb 2021
Cited by 5 | Viewed by 2773
Abstract
The current study introduces a method for manufacturing steel–aluminum bearing bushings by compound forging. To study the process, cylindrical bimetal workpieces consisting of steel AISI 4820 (1.7147, 20MnCr5) in the internal diameter and aluminum 6082 (3.2315, AlSi1MgMn) in the external diameter were used. [...] Read more.
The current study introduces a method for manufacturing steel–aluminum bearing bushings by compound forging. To study the process, cylindrical bimetal workpieces consisting of steel AISI 4820 (1.7147, 20MnCr5) in the internal diameter and aluminum 6082 (3.2315, AlSi1MgMn) in the external diameter were used. The forming of compounds consisting of dissimilar materials is challenging due to their different thermophysical and mechanical properties. The specific heating concept discussed in this article was developed in order to achieve sufficient formability for both materials simultaneously. By means of tailored heating, the bimetal workpieces were successfully formed to a bearing bushing geometry using two different strategies with different heating durations. A metallurgical bond without any forging defects, e.g., gaps and cracks, was observed in areas of high deformation. The steel–aluminum interface was subsequently examined by optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It was found that the examined forming process, which utilized steel–aluminum workpieces having no metallurgical bond prior to forming, led to the formation of insular intermetallic phases along the joining zone with a maximum thickness of approximately 5–7 µm. The results of the EDS analysis indicated a prevailing FexAly phase in the resulting intermetallic layer. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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15 pages, 7855 KiB  
Article
Case Study of the Effect of Precoating on the Decarburization of the Surface Layer of Forged Parts during the Hot Die Forging Process
by Paweł Widomski, Maciej Zwierzchowski, Artur Barełkowski and Mateusz Tympalski
Materials 2021, 14(2), 422; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14020422 - 16 Jan 2021
Cited by 4 | Viewed by 1956
Abstract
This paper aims to evaluate the effect of pre-coating of forged parts on decarburization in the die forging process. The studies consisted of three stages. In the first instance, different coatings were tested under laboratory conditions by heating steel samples to the temperature [...] Read more.
This paper aims to evaluate the effect of pre-coating of forged parts on decarburization in the die forging process. The studies consisted of three stages. In the first instance, different coatings were tested under laboratory conditions by heating steel samples to the temperature of 1200 °C for over five minutes to model the preheating conditions of the induction. Next, testing continued in a commercial forging stand where we tested the effects of different coatings on the rods decarburization during the induction heating process, usually performed before forging. Once completed testing, the measurements and observations of the decarbonized layer were made. The third stage involved analysis of the decarburization of the forged parts after forging. The forged parts were made using precoating of pre-forging elements; pieces cut off a metal rod. Based on tests results, the possibility of using this solution in the technique of industrial hot forging was evaluated. The results of laboratory tests have confirmed that lubrication of metal pieces is sufficient, as well as proved it to be effective in reducing decarburization of the surface layer. Research works conducted in an induction heater showed differences in decarburization depending on a substance and concentration of lubricants that were used. These differences become more apparent when observing the surface layer of the forged parts. Results indicate that decarburization may be reduced to a minimum when we use Bonderite product in a concentration of 66% and 50%. Another lubricant, Berulit 913, may also be used. However, due to burning graphite in high temperatures, reduction of decarburization goes only as far as half of the thickness of the decarbonized layer. Condursal has no significant effect; nevertheless, it protects over the induction heating stage. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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14 pages, 4935 KiB  
Article
Advanced Complex Analysis of the Thermal Softening of Nitrided Layers in Tools during Hot Die Forging
by Jakub Krawczyk, Paweł Widomski and Marcin Kaszuba
Materials 2021, 14(2), 355; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14020355 - 13 Jan 2021
Cited by 5 | Viewed by 1625
Abstract
This article is devoted to the issues of thermal softening of materials in the surface layer of forging tools. The research covers numerical modeling of the forging process, laboratory tests of tempering of nitrided layers, and the analysis of tempering of the surface [...] Read more.
This article is devoted to the issues of thermal softening of materials in the surface layer of forging tools. The research covers numerical modeling of the forging process, laboratory tests of tempering of nitrided layers, and the analysis of tempering of the surface layer of tools in the actual forging process. Numerical modeling was supported by measuring the temperature inside the tools with a thermocouple inserted into the tool to measure the temperature as close to the surface as possible. The modeling results confirmed the possibility of tempering the die material. The results of laboratory tests made it possible to determine the influence of temperature on tempering at different surface layer depths. Numerical analysis and measurement of surface layer microhardness of tools revealed the destructive effect of temperature during forging on the tempering of the nitrided layer and on the material layers located deeper below the nitrided layer. The results have shown that in the hot forging processes carried out in accordance with the adopted technology, the surface layer of working tools is overheated locally to a temperature above 600 °C and tempering occurs. Moreover, overheating effects are visible, because the surface layer is tempered to a depth of 0.3 mm. Finally, such tempering processes lead to a decrease in the die hardness, which causes accelerated wear because of the abrasion and plastic deformation. The nitriding does not protect against the tempering phenomenon, but only delays the material softening process, because tempering occurs in the nitrided layer and in the layers deeper under the nitrided layer. Below the nitrided layer, tempering occurs relatively quickly and a soft layer is formed with a hardness below 400 HV. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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10 pages, 4295 KiB  
Article
Investigation on the Microstructure of ECAP-Processed Iron-Aluminium Alloys
by Bernd-Arno Behrens, Kai Brunotte, Tom Petersen and Roman Relge
Materials 2021, 14(1), 219; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14010219 - 05 Jan 2021
Cited by 1 | Viewed by 1815
Abstract
The present work deals with adjusting a fine-grained microstructure in iron-rich iron-aluminium alloys using the ECAP-process (Equal Channel Angular Pressing). Due to the limited formability of Fe-Al alloys with increased aluminium content, high forming temperatures and low forming speeds are required. Therefore, tool [...] Read more.
The present work deals with adjusting a fine-grained microstructure in iron-rich iron-aluminium alloys using the ECAP-process (Equal Channel Angular Pressing). Due to the limited formability of Fe-Al alloys with increased aluminium content, high forming temperatures and low forming speeds are required. Therefore, tool temperatures above 1100 °C are permanently needed to prevent cooling of the work pieces, which makes the design of the ECAP-process challenging. For the investigation, the Fe-Al work pieces were heated to the respective hot forming temperature in a chamber furnace and then formed in the ECAP tool at a constant punch speed of 5 mm/s. Besides the chemical composition (Fe9Al, Fe28Al and Fe38Al (at.%—Al)), the influences of a subsequent heat treatment and the holding time on the microstructure development were investigated. For this purpose, the average grain size of the microstructure was measured using the AGI (Average Grain Intercept) method and correlated with the aforementioned parameters. The results show that no significant grain refinement could be achieved with the parameters used, which is largely due to the high forming temperature significantly promoting grain growth. The holding times in the examined area do not have any influence on the grain refinement. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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15 pages, 7311 KiB  
Article
Simulation of Dynamic and Meta-Dynamic Recrystallization Behavior of Forged Alloy 718 Parts Using a Multi-Class Grain Size Model
by Christian Gruber, Peter Raninger, Aleksandar Stanojevic, Flora Godor, Markus Rath, Ernst Kozeschnik and Martin Stockinger
Materials 2021, 14(1), 111; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14010111 - 29 Dec 2020
Cited by 8 | Viewed by 2065
Abstract
Dynamic and meta-dynamic recrystallization occur during forging of alloy 718 aircraft parts and thus change the microstructure during a multistep production route. Since the prediction of the resulting grain structure in a single grain fraction is not able to describe microstructures with bimodal [...] Read more.
Dynamic and meta-dynamic recrystallization occur during forging of alloy 718 aircraft parts and thus change the microstructure during a multistep production route. Since the prediction of the resulting grain structure in a single grain fraction is not able to describe microstructures with bimodal or even multimodal distributions, a multi-class grain size model has been deployed to describe the recrystallization mechanisms during thermomechanical treatments and predict the resulting grain size distributions more accurately. As forging parameters, such as temperature, strain rate and maximum strain influence the flow curve and consequently the recrystallization behavior, a series of double cone compression experiments has been carried out and used to verify and adapt the material parameters for the multi-class grain size model. The recrystallized fractions of the numerical and experimental results are compared and differentiated in view of the recrystallization mechanism, i.e., dynamic and meta-dynamic recrystallization. The strong dependence of the recrystallization kinetics on the initial grain size is highlighted, as well as the influence of different strain rates, which shall represent typical forging equipment. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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16 pages, 7512 KiB  
Article
Multi-Layer Wear and Tool Life Calculation for Forging Applications Considering Dynamical Hardness Modeling and Nitrided Layer Degradation
by Bernd-Arno Behrens, Kai Brunotte, Hendrik Wester, Marcel Rothgänger and Felix Müller
Materials 2021, 14(1), 104; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14010104 - 29 Dec 2020
Cited by 8 | Viewed by 2146
Abstract
As one of the oldest shaping manufacturing processes, forging and especially hot forging is characterized by extreme loads on the tool. The thermal load in particular is able to cause constant changes in the hardness of the surface layer, which in turn has [...] Read more.
As one of the oldest shaping manufacturing processes, forging and especially hot forging is characterized by extreme loads on the tool. The thermal load in particular is able to cause constant changes in the hardness of the surface layer, which in turn has a decisive influence on the numerical estimation of wear. Thus, also during numerical wear, modeling hardness changes need to be taken into account. Within the scope of this paper, a new implementation of a numerical wear model is presented, which, in addition to dynamic hardness models for the base material, can also take into account the properties of a nitride wear protection layer as a function of the wear depth. After a functional representation, the new model is applied to the wear calculation of a multi-stage industrial hot forging process. The applicability of the new implementation is validated by the evaluation of the occurring hardness, wear depths and the locally associated removal of the wear protection layer. Consecutively, a tool life calculation module based on the calculated wear depth is implemented and demonstrated. In general, a good agreement of the results is achieved, making the model suitable for detailed 2D as well as large 3D Finite Element calculations. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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18 pages, 5830 KiB  
Article
Material Flow in Infeed Rotary Swaging of Tubes
by Yang Liu, Jing Liu, Marius Herrmann, Christian Schenck and Bernd Kuhfuss
Materials 2021, 14(1), 58; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14010058 - 24 Dec 2020
Cited by 9 | Viewed by 2290
Abstract
Rotary swaging is an incremental metal forming process widely used to reduce the cross–section of parts. For tubular parts, the final wall thickness also changes during the process. The lubricant condition is a factor, which affects these geometry changes. Beneath the change of [...] Read more.
Rotary swaging is an incremental metal forming process widely used to reduce the cross–section of parts. For tubular parts, the final wall thickness also changes during the process. The lubricant condition is a factor, which affects these geometry changes. Beneath the change of the geometry, the complex material flow during the process determines the final geometry and the mechanical properties. Therefore, with a thorough insight into the material flow, it could be understood how to control it in order to achieve desired properties. Producing tubes with uniform outer diameter and changing inner profiles is an application of this method. Furthermore, applying this method, different local cold hardening could be achieved by different total strain. In this study, the dependency of the material flow on the lubrication conditions was investigated. Simulations with combined hardening material models were verified by the change of the wall thickness of tubes. It was found that friction condition significantly influences the back shifting of the workpiece and the elongation caused by each stroke. Results from simulations and experiments showed that a certain lubricant condition leads to the highest axial elongation of the workpiece. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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21 pages, 26713 KiB  
Article
Forging of Mg-Al-Zn Magnesium Alloys on Screw Press and Forging Hammer
by Andrzej Gontarz, Krzysztof Drozdowski, Jacek Michalczyk, Sylwia Wiewiórowska, Zbigniew Pater, Janusz Tomczak, Grzegorz Samołyk, Grzegorz Winiarski and Piotr Surdacki
Materials 2021, 14(1), 32; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14010032 - 23 Dec 2020
Cited by 5 | Viewed by 2500
Abstract
Magnesium alloys are highly strain rate sensitive and exhibit good workability in a narrow forging temperature range. Consequently, parts made of these materials are usually forged with low-speed hydraulic presses, using specially designed tool heating systems in order to ensure near-isothermal conditions. This [...] Read more.
Magnesium alloys are highly strain rate sensitive and exhibit good workability in a narrow forging temperature range. Consequently, parts made of these materials are usually forged with low-speed hydraulic presses, using specially designed tool heating systems in order to ensure near-isothermal conditions. This study investigates whether popular magnesium alloys such as Mg-Al-Zn can be forged in forging machines equipped with high-speed forming tools. Experimental upset forging tests on AZ31B, AZ61A and AZ80A specimens were conducted, using a screw press with a ram speed of 0.5 m/s and a die forging hammer with a ram speed at stroke of about 5 m/s. Test specimens were preheated to 350 °C, 410 °C and 450 °C. After the upset forging process, they were air- or water-cooled and then examined for their workability, hardness and grain size. To validate the results, a forging process for a producing handle was designed and modelled by the finite element method. Distributions of strain, temperature and fracture criterion were analysed, and energy and force parameters of the forging process were calculated. After that, experimental tests were performed on AZ31B and AZ61A specimens in order to determine mechanical properties of forged parts and examine their micro- and macrostructure. Results have demonstrated that AZ80A is not suitable for forging with either the screw press or the die forging hammer, that AZ61A can be press- and hammer-forged but to a limited extent, and that AZ31B can be subjected to forging in both forging machines analysed in the study. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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22 pages, 134008 KiB  
Article
Physical and Numerical Simulations of Closed Die Hot Forging and Heat Treatment of Forged Parts
by Łukasz Poloczek, Łukasz Rauch, Marek Wilkus, Daniel Bachniak, Władysław Zalecki, Valeriy Pidvysotsk’yy, Roman Kuziak and Maciej Pietrzyk
Materials 2021, 14(1), 15; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14010015 - 22 Dec 2020
Cited by 3 | Viewed by 2578
Abstract
The paper describes physical and numerical simulations of a manufacturing process composed of hot forging and controlled cooling, which replace the conventional heat treatment technology. The objective was to investigate possibilities and limitations of the heat treatment with the use of the heat [...] Read more.
The paper describes physical and numerical simulations of a manufacturing process composed of hot forging and controlled cooling, which replace the conventional heat treatment technology. The objective was to investigate possibilities and limitations of the heat treatment with the use of the heat of forging. Three steels used to manufacture automotive parts were investigated. Experiments were composed of two sets of tests. The first were isothermal (TTT) and constant cooling rate (CCT) dilatometric tests, which supplied data for the identification of the numerical phase transformation model. The second was a physical simulation of the sequence forging-cooling on Gleeble 3800, which supplied data for the validation of the models. In the numerical part, a finite element (FE) thermal-mechanical code was combined with metallurgical models describing recrystallization and grain growth during forging and phase transformations during cooling. The FE model predicted distributions of the temperature and the austenite grain size in the forging, which were input data for further simulations of phase transformations during cooling. A modified JMAK equation was used to calculate the kinetics of transformation and volume fraction of microstructural constituents after cooling. Since the dilatometric tests were performed for various austenitization temperatures before cooling, it was possible to include austenite grain size as a variable in the model. An inverse algorithm developed by the authors was applied in the identification procedure. The model with optimal material parameters was used for simulations of hot forging and controlled cooling in one of the forging shops in Poland. Distributions of microstructural constituents in the forging after cooling were calculated. As a consequence, various cooling sequences during heat treatment could be analyzed and compared. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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13 pages, 3968 KiB  
Article
Mechanical and Thermal Influences on Microstructural and Mechanical Properties during Process-Integrated Thermomechanically Controlled Forging of Tempering Steel AISI 4140
by Bernd-Arno Behrens, Kai Brunotte, Tom Petersen and Julian Diefenbach
Materials 2020, 13(24), 5772; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13245772 - 17 Dec 2020
Cited by 5 | Viewed by 1711
Abstract
Thermomechanical treatment (TMT) describes the effect of thermal and mechanical conditions on the microstructure of materials during processing and offers possible integration in the forging process. TMT materials exhibit a fine-grained microstructure, leading to excellent mechanical properties. In this study, a two-step TMT [...] Read more.
Thermomechanical treatment (TMT) describes the effect of thermal and mechanical conditions on the microstructure of materials during processing and offers possible integration in the forging process. TMT materials exhibit a fine-grained microstructure, leading to excellent mechanical properties. In this study, a two-step TMT upsetting process with intermediate cooling is used to demonstrate possibilities for a process-integrated treatment and corresponding properties. A water–air-based cooling system was designed to adjust different phase configurations by varying the target temperature and cooling rate. Four different thermal processing routes and four combinations of applied plastic strains are investigated in standardized mechanical tests and metallographic analyses. The applied TMT results in a finely structured bainitic microstructure of the investigated tempering steel AISI 4140 (42CrMo4) with different characteristics depending on the forming conditions. It can be shown that the demands of the standard (DIN EN ISO 683) in a quenched and tempered state can be fulfilled by means of appropriate forming conditions. The yield strength can be enhanced up to 1174 MPa while elongation at break is about 12.6% and absorbed impact energy reaches 58.5 J without additional heat treatment when the material is formed after rapid cooling. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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12 pages, 4756 KiB  
Article
Thermomechanical Processing of a Near-α Ti Matrix Composite Reinforced by TiBw
by Hong Feng, Yonggang Sun, Yuzhou Lian, Shuzhi Zhang, Changjiang Zhang, Ying Xu and Peng Cao
Materials 2020, 13(24), 5751; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13245751 - 16 Dec 2020
Cited by 2 | Viewed by 1305
Abstract
To further improve the mechanical properties of the as-cast 7.5 vol.% TiBw/Ti–6Al–2.5Sn–4Zr–0.7Mo–0.3Si composite, multi-directional forging (MDF) and subsequent heat treatments were carried out to adjust TiB whiskers (TiBw) and matrix characteristics. The effect of various microstructures on the tensile [...] Read more.
To further improve the mechanical properties of the as-cast 7.5 vol.% TiBw/Ti–6Al–2.5Sn–4Zr–0.7Mo–0.3Si composite, multi-directional forging (MDF) and subsequent heat treatments were carried out to adjust TiB whiskers (TiBw) and matrix characteristics. The effect of various microstructures on the tensile properties and fracture toughness of the composites was analyzed in this paper. After MDF, the TiBw are broken into short rods with a low aspect ratio and display a random distribution. Moreover, distinct microstructures were obtained after thermomechanical processing and different heat treatments. Both room-temperature and high-temperature tensile strength and ductility are improved after thermomechanical processing. By increasing the solution-treatment temperature, the microstructures transform from equiaxed to fully lamellar. A simultaneous improvement of the room-temperature and high-temperature properties is associated with the microstructural changes. In addition, the fracture toughness exhibits an increasing trend as the volume fraction of equiaxial α phases decreases. The lamellar microstructure demonstrates excellent fracture toughness due to deflection of the crack propagation path. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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17 pages, 7053 KiB  
Article
Analysis of Deformation and Prediction of Cracks in the Cogging Process for Die Steel at Elevated Temperatures
by Marcin Kukuryk
Materials 2020, 13(24), 5589; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13245589 - 08 Dec 2020
Cited by 4 | Viewed by 1663
Abstract
In this paper, an analysis of a three-dimensional state of strain and stress in the case of the hot cogging process of X32CrMoV12-28 die steel with the application of the finite element method is presented. The results of the investigations connected with the [...] Read more.
In this paper, an analysis of a three-dimensional state of strain and stress in the case of the hot cogging process of X32CrMoV12-28 die steel with the application of the finite element method is presented. The results of the investigations connected with the simulation of the kinematics of metal flow and thermal phenomena are presented, accompanied by prognosing the formation of ductile fractures in the course of the hot cogging process conducted with the application of three different shape tools and of a proposed deformation criterion of the loss of cohesion. The applied anvils were found to be highly effective in the aspects of distribution of effective strains and stresses, absence of tensile stresses in the axial zones of a forging, and also of a significant thermal stability in the internal layers of a deformed material. The developed course of changes in the deformation of the damage factor in the case of forging in the investigated anvils renders it possible to predict the situation and the phase of deformation in which the loss of cohesion by a deformed material will occur. The comparison between the predicted and the experimental results showed a good agreement. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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10 pages, 3522 KiB  
Article
Influence of Alloying Elements on the Dynamic Recrystallization of 4 wt.–% Medium Manganese Steels
by Alexander Gramlich, Hanne Schäfers and Ulrich Krupp
Materials 2020, 13(22), 5178; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13225178 - 17 Nov 2020
Cited by 3 | Viewed by 2452
Abstract
The hot deformation behaviour of air-hardening martensitic forging steels (of type 1.5132) is presented. The newly developed steels are characterized through dilatometric tests as well as through microstructure analyses with LOM and SEM and hardness measurements. Additionally, the influence of alloying elements on [...] Read more.
The hot deformation behaviour of air-hardening martensitic forging steels (of type 1.5132) is presented. The newly developed steels are characterized through dilatometric tests as well as through microstructure analyses with LOM and SEM and hardness measurements. Additionally, the influence of alloying elements on the flow curves at high temperatures is discussed. It is demonstrated that the higher alloying content does not increase the equivalent stresses in comparison to the reference alloys and contrariwise reduces the offset for dynamic recrystallization at temperatures below 1100 ∘C. Furthermore, the effect of different alloying elements on the strain hardening behaviour during hot compression of 4wt.–% medium manganese steels is presented. It is shown that boron reduces the offset for dynamic recrystallization if present in solid solution, while the combined addition of titanium and niobium annihilates the solid drag effect on the prior austenite grain boundaries. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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10 pages, 3874 KiB  
Article
Cross-Section Deformation and Bending Moment of a Steel Square Tubular Section
by Stanisław Kut and Feliks Stachowicz
Materials 2020, 13(22), 5170; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13225170 - 16 Nov 2020
Cited by 5 | Viewed by 1958
Abstract
When bending thin-walled profiles, significant distortion of the cross-section occurs, which has a significant impact on the course of the bending moment characteristics and on the value of allowable bending curvatures. This paper presents the results of experimental and numerical modeling of the [...] Read more.
When bending thin-walled profiles, significant distortion of the cross-section occurs, which has a significant impact on the course of the bending moment characteristics and on the value of allowable bending curvatures. This paper presents the results of experimental and numerical modeling of the box profile bending process, which was carried out in order to determine the dependence of the cross-sectional shape and bending moment of bending curvature. Extensive numerical calculations were used to model the process of shaping a square pipe from a circular tube and to model the bending process, especially when taking into account the effects of such a deformation path. The pure bending moment characteristics and the deformation of the cross-section were performed for a 25 × 25 × 2 mm square tube made of S235JR structural steel. The innovative approach for determining the parameters of cold bending square tubes pertained to considering the stress state in the preserved material in individual areas of their cross-section. The results of numerical modeling—after considering the history of deformation (i.e., the process of forming a square pipe from a pipe with a circular cross-section)—gave a satisfactory agreement with the results of experimental tests, both in terms of the degree of pipe wall deflection and the characteristics of the bending moment. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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14 pages, 6612 KiB  
Article
Preliminary Study on the Capability of the Novel Near Solidus Forming (NSF) Technology to Manufacture Complex Steel Components
by Gorka Plata, Jokin Lozares, Andrea Sánchez, Iñaki Hurtado and Carl Slater
Materials 2020, 13(20), 4682; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13204682 - 21 Oct 2020
Cited by 3 | Viewed by 1957
Abstract
The benefits of the novel Near Solidus Forming (NSF) process has shown previously in its ability to produce steel components with comparable as-forged mechanical properties but with a cost reduction of 10–15%. This study further pushes the NSF technology to produce parts that [...] Read more.
The benefits of the novel Near Solidus Forming (NSF) process has shown previously in its ability to produce steel components with comparable as-forged mechanical properties but with a cost reduction of 10–15%. This study further pushes the NSF technology to produce parts that are conventionally difficult to produce via conventional methods. A 2.7 kg 42CrMo4 steel grade component was manufactured into a complex geometry using only a 400t press. Different manufacturing parameters were evaluated to show their influence on the process and final component. A combination of X-ray fluorescence (XRF), optical microscopy and SEM analysis of the microstructure was also conducted revealing the deformation pattern of the material and shedding some light on how the material evolves during the process. The successful forging of these components shows the capability to produce previously deemed difficult geometries, with much a lower specification forging press, in a single deformation. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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13 pages, 6331 KiB  
Article
Effect of Rotation of the Principal Stress Axes Relative to the Material on the Evolution of Material Properties in Severe Plastic Deformation Processes
by Marko Vilotic, Leposava Sidjanin, Sergei Alexandrov and Lihui Lang
Materials 2020, 13(20), 4667; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13204667 - 20 Oct 2020
Viewed by 1999
Abstract
Severe plastic deformation (SPD) processes are widely used for improving material properties. A distinguishing feature of many SPD processes is that the principal axes of the stress tensor intensively rotate relative to the material. Nevertheless, no measure of this rotation is involved in [...] Read more.
Severe plastic deformation (SPD) processes are widely used for improving material properties. A distinguishing feature of many SPD processes is that the principal axes of the stress tensor intensively rotate relative to the material. Nevertheless, no measure of this rotation is involved in the constitutive equations that predict the evolution of material properties. In particular, a typical way of describing the effect of SPD processes on material properties is to show the dependence of various parameters that characterize these properties on the equivalent strain. However, the same level of the equivalent strain can be achieved in a process in which the principal axes of the stress tensor do not rotate relative to the material. It is, therefore, vital to understand which properties are dependent and which properties are independent of the rotation of the principal axes of the stress tensor relative to the material. In the present paper, a new multistage SPD process is designed such that the principal stress axes do not rotate relative to the material during each stage of the process but the directions of the major and minor principal stresses interchange between two subsequent stages. The process is practically plane strain, and it may be named the process of upsetting by V-shape dies. In addition, axisymmetric compression by Rastegaev’s method is conducted. In this case, the principal stress axes are fixed in the material throughout the entire process of deformation. Material properties and microstructure generated in the two processes above are compared to reveal the effect of the rotation of the principal stress axes relative to the material on the evolution of these properties. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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13 pages, 4095 KiB  
Article
Theoretical and Experimental Analysis of a New Process for Forming Flanges on Hollow Parts
by Grzegorz Winiarski, Andrzej Gontarz and Grzegorz Samołyk
Materials 2020, 13(18), 4088; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13184088 - 15 Sep 2020
Cited by 10 | Viewed by 2275
Abstract
The paper presented a new method for forming flanges on hollow parts by incremental radial extrusion. In the classic process of radial extrusion, additional rings were used to limit the free flow of material in the radial direction. The flange was formed progressively, [...] Read more.
The paper presented a new method for forming flanges on hollow parts by incremental radial extrusion. In the classic process of radial extrusion, additional rings were used to limit the free flow of material in the radial direction. The flange was formed progressively, using rings of increasing diameters. The proposed method was verified by numerical analysis and experimental tests. The numerical calculations were performed by the finite element method using the Deform-3D software package. Tubes made of aluminum alloy EN AW 6060 were used as billets. Laboratory tests were carried out using the Instron 1000 HDX testing machine. The objective of the study was to determine the validity of the proposed flange extrusion method. Results demonstrated that the new method made it possible to produce flanges with a relatively large diameter and uniform thickness, confirming the effectiveness of the proposed forming technique. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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20 pages, 3984 KiB  
Article
Analysis of the Open Die Forging Process of the AZ91 Magnesium Alloy
by Grzegorz Banaszek, Teresa Bajor, Anna Kawałek and Tomasz Garstka
Materials 2020, 13(17), 3873; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13173873 - 02 Sep 2020
Cited by 8 | Viewed by 3063
Abstract
The paper presents the results of numerical modelling of the forging process of magnesium alloy ingots on a hydraulic press with the use of flat and shaped anvils. The use of shaped (rhombic-trapezoid) anvils will affect the uniform distribution of temperature [...] Read more.
The paper presents the results of numerical modelling of the forging process of magnesium alloy ingots on a hydraulic press with the use of flat and shaped anvils. The use of shaped (rhombic-trapezoid) anvils will affect the uniform distribution of temperature and strain intensity in the entire volume of the forging, causing a number of forging passes, which in consequence will reduce the costs of the blank manufacturing process. However, higher values of the strain intensity were obtained during the deformation of the material in flat anvils. The purpose of the research was to propose assumptions for forging technology of producing a blank from AZ91 alloy with the use of flat and shaped anvils. Numerical examination for AZ91 magnesium alloy was carried out using the Forge®NxT commercial software. The rheological properties of the investigated alloy were determined on the basis of uniaxial compression tests carried out in the Gleeble 3800 metallurgical simulation system. The numerical analysis of the process of forging AZ91 alloy ingots on a press was conducted in the temperature range of 200–400 °C and at several forging passes. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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11 pages, 10058 KiB  
Article
Dry Cold Forging of Pure Titanium Wire to Thin Plate with Use of β-SiC Coating Dies
by Tatsuhiko Aizawa, Tomoaki Yoshino, Tatsuya Fukuda and Tomomi Shiratori
Materials 2020, 13(17), 3780; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13173780 - 27 Aug 2020
Cited by 4 | Viewed by 1958
Abstract
Dense β-SiC coating with 3C-structure was utilized as a dry cold forging punch and core-die. Pure titanium T328H wires of industrial grade II were employed as a work material. No adhesion or galling of metallic titanium was detected on the contact interface between [...] Read more.
Dense β-SiC coating with 3C-structure was utilized as a dry cold forging punch and core-die. Pure titanium T328H wires of industrial grade II were employed as a work material. No adhesion or galling of metallic titanium was detected on the contact interface between this β-SiC die and titanium work, even after this continuous forging process, up to a reduction in thickness by 70%. SEM (Scanning Electron Microscopy) and EDX (Electron Dispersive X-ray spectroscopy) were utilized to analyze this contact interface. A very thin titanium oxide layer was in situ formed in the radial direction from the center of the contact interface. Isolated carbon from β-SiC agglomerated and distributed in dots at the center of the initial contact interface. Raman spectroscopy was utilized, yielding the discovery that this carbon is unbound as a free carbon or not bound in SiC or TiC and that intermediate titanium oxides are formed with TiO2 as a tribofilm. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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17 pages, 15126 KiB  
Article
Evaluation of Hot Workability of Nickel-Based Superalloy Using Activation Energy Map and Processing Maps
by Oleksandr Lypchanskyi, Tomasz Śleboda, Krystian Zyguła, Aneta Łukaszek-Sołek and Marek Wojtaszek
Materials 2020, 13(16), 3629; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13163629 - 17 Aug 2020
Cited by 17 | Viewed by 2782
Abstract
The stress-strain curves for nickel-based superalloy were obtained from isothermal hot compression tests at a wide range of deformation temperatures and strain rates. The material constants and deformation activation energy of the investigated superalloy were calculated. The accuracy of the constitutive equation describing [...] Read more.
The stress-strain curves for nickel-based superalloy were obtained from isothermal hot compression tests at a wide range of deformation temperatures and strain rates. The material constants and deformation activation energy of the investigated superalloy were calculated. The accuracy of the constitutive equation describing the hot deformation behavior of this material was confirmed by the correlation coefficient for the linear regression. The distribution of deformation activation energy Q as a function of strain rate and temperature for nickel-based superalloy was presented. The processing maps were generated upon the basis of Prasad stability criterion for true strains ranging from 0.2 to 1 at the deformation temperatures range of 900–1150 °C, and strain rates range of 0.01–100 s−1. Based on the flow stress curves analysis, deformation activation energy map, and processing maps for different true strains, the undesirable and potentially favorable hot deformation parameters were determined. The microstructural observations confirmed the above optimization results for the hot workability of the investigated superalloy. Besides, the numerical simulation and industrial forging tests were performed in order to verify the obtained results. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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16 pages, 5445 KiB  
Article
Feasibility of Reduced Ingot Hot-Top Height for the Cost-Effective Forging of Heavy Steel Ingots
by Nam Yong Kim, Dae-Cheol Ko, Yangjin Kim, Sang Wook Han, Il Yeong Oh and Young Hoon Moon
Materials 2020, 13(13), 2916; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13132916 - 29 Jun 2020
Cited by 2 | Viewed by 2821
Abstract
Feasibility studies have been performed on ingots with reduced hot-top heights for the cost-effective hot forging of heavy ingots. The quality of the heavy ingots is generally affected by internal voids, which have been known to be accompanied by inclusions and segregation. To [...] Read more.
Feasibility studies have been performed on ingots with reduced hot-top heights for the cost-effective hot forging of heavy ingots. The quality of the heavy ingots is generally affected by internal voids, which have been known to be accompanied by inclusions and segregation. To guarantee the expected mechanical performance of the forged products, these voids should be closed and eliminated during the hot open die forging process. Hence, to effectively control the internal voids, the optimum hot-top height and forging schedules need to be determined. In order to improve the utilization ratio of ingots, the ingot hot-top height needs to be minimized. To investigate the effect of the reduced hot-top height on the forged products, shaft and bar products have been manufactured via hot forging of ingots having various hot-top heights. From the operational results, the present work suggests effective forging processes to produce acceptable shaft and bar products using ingots having reduced hot tops. The mechanical properties of shop-floor products manufactured from ingots with reduced hot tops have also been measured and compared with those of conventional ingot products. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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19 pages, 9228 KiB  
Article
Application of a Prototype Thermoplastic Treatment Line in Order to Design a Thermal Treatment Process of Forgings with the Use of the Heat from the Forging Process
by Marek Hawryluk, Zbigniew Gronostajski, Maciej Zwierzchowski, Paweł Jabłoński, Artur Barełkowski, Jakub Krawczyk, Karol Jaśkiewicz and Marcin Rychlik
Materials 2020, 13(11), 2441; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13112441 - 27 May 2020
Cited by 4 | Viewed by 2181
Abstract
The global production of die forgings is an important branch of the motor industry for obvious reasons, resulting from the very good mechanical properties of the forged products. The expectations of the recipients, beside the implementation of the forging process, include also a [...] Read more.
The global production of die forgings is an important branch of the motor industry for obvious reasons, resulting from the very good mechanical properties of the forged products. The expectations of the recipients, beside the implementation of the forging process, include also a range of supplementary procedures, such as finishing treatment including shot blasting, thermal treatment, and machining, in order to ensure the proper quality of the provided semi-product or the ready detail for the assembly line. Especially important in the aspect of the operational properties of the products is the thermal treatment of the forgings, which can be implemented in many variants, depending on the expected results. Unfortunately, a treatment of this type, realized separately after the forging process, is very time and energy-consuming; additionally, it significantly raises the production costs due to the increased energy consumption resulting from the necessity of repeated heating of the forgings for such thermal treatment. The article reviews the most frequently applied (separately, after the forging process) thermal treatments for die forgings together with the devices/lines assigned for them, as well as presents an alternative (thermoplastic) method of forging production with the use of the forging heat. The paper also presents a prototype semi-industrial controlled cooling line developed by the authors, which allows the development of the assumed heat treatment of forgings directly after forging with the use of forging heat, together with sample results of conducted tests. Full article
(This article belongs to the Special Issue Forging Processes of Materials)
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