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Metal Forming: Fundamentals, Simulation and Applications

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

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 35331

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Dr. Sang-Kon Lee

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Korea Institute of Industrial Technology, 320, Techno Sunhwan-ro, Yuga-myeon, Dalseong-gun, Daegu 42990, Korea
Interests: metal forming; wire drawing; lightweight alloy extrusion; flexible forming process

Special Issue Information

Dear Colleagues,

Metal forming processes are a representative manufacturing method for mass production. In general, products manufactured via the metal forming process have very excellent dimensional accuracy and mechanical properties. Today, many kinds of metal forming processes are used in various representative industries, including automobile, aircrafts, machinery, electrics/electronics, and so on. Although metal forming processes are a traditional method, they are a very important manufacturing method that requires continuous development. In particular, various studies are needed for cost reduction, high precision, low energy consumption, production flexibility, and process convergence.

The aim of this Special Issue is to publish the outstanding papers in various metal forming processes including conventional and advanced processes based on experiment and/or numerical analysis. Through this Special Issue, understanding and development of metal forming processes are expected.

The topics of interest include but are not limited to scientific contributions on the following metal forming processes:

Bulk metal forming;
Sheet metal forming;
Numerical modeling of metal forming process;
Powder forming process;
Metal 3D printing;
Advanced or hybrid forming processes;
Multimaterial forming process;
Mechanical joining process;
Material behavior in metal forming process.

Dr. Sang-Kon Lee
Guest Editor

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Keywords

metal forming process
advanced forming process
numerical analysis
material behavior

Published Papers (12 papers)

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Research

22 pages, 5931 KiB

Open AccessArticle

Investigation of the Microstructural Evolution during Hot Stamping of a Carburized Complex Phase Steel by Laser-Ultrasonics

by Alexander Horn and Marion Merklein

Materials 2021, 14(8), 1836; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14081836 - 07 Apr 2021

Cited by 3 | Viewed by 1865

Abstract

Prior carburization of semi-finished steel sheets is a new process variant in hot stamping to manufacture parts with tailored properties. Compared to conventional hot stamping processes, a complex phase typed steel alloy is used instead of 22MnB5. Yet recent investigations focused on final mechanical properties rather than microstructural mechanisms cause an increase in strength. Thus, the influence of additional carburization on the microstructural evolution during hot stamping of a complex phase steel CP-W^®800 is investigated within this work. The phase transformation behavior, as well as the grain growth during austenitization, is evaluated by in-situ measurements employing a laser-ultrasound sensor. The results are correlated with additional hardness measurements in as-quenched condition and supplementary micrographs. The experiments reveal that the carburization process significantly improves the hardenability of the CP-W^®800. However, even at quenching rates of 70 K/s no fully martensitic microstructure was achievable. Still, the resulting hardness of the carburized samples might exceed the fully martensitic hardness of 22MnB5 derived from literature. Furthermore, the carburization process has no adverse effect on the fine grain stability of the complex phase steel. This makes it more robust in terms of grain size than the conventional hot stamping steel 22MnB5. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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22 pages, 16001 KiB

Open AccessArticle

Modeling of Microstructure Evolution during Deformation Processes by Cellular Automata—Boundary Conditions and Space Reorganization Aspects

by Łukasz Łach

Materials 2021, 14(6), 1377; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14061377 - 12 Mar 2021

Cited by 4 | Viewed by 1686

Abstract

Cellular automata (CA) are efficient and effective numerical tools for modeling various phenomena and processes, e.g., microstructure evolution in plastic working processes. In many cases, the analysis of phenomena can be carried out only in a limited space and on representative volume. This limitation determines the geometry of CA space hence boundary conditions are very important issues in modeling. The paper discusses different boundary conditions that can be applied to modeling. Taking into account the transformation of the modeling space, the model should allow the selection of boundary conditions. The modeling of certain phenomena and processes is directly related to changes in the geometry of a representative volume and therefore may require changes or reorganization of the modeled CA space. Four reorganization options are presented: halving, cutting and bonding, doubling, and straightening. A choice of boundary conditions may depend on particular space reorganization as used for the modeling of microstructure evolution. A set of decision rules for selecting space reorganization options taking into account the changes of CA shape and sizes is also presented. The modeling of flat and shape rolling processes utilizing some of the described techniques is shown. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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14 pages, 5377 KiB

Open AccessArticle

Effect of a Multiple Reduction Die on the Residual Stress of Drawn Materials

by Jeong-Hun Kim, Chang-Hyun Baek, Sang-Kon Lee, Jong-Hun Kang, Joon-Hong Park and Dae-Cheol Ko

Materials 2021, 14(6), 1358; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14061358 - 11 Mar 2021

Cited by 2 | Viewed by 1395

Abstract

Residual stress may influence the mechanical behavior and durability of drawn materials. Thus, this study develops a multiple reduction die (MRD) that can reduce residual stress during the drawing process. The MRD set consists of several die tips, die cases, and lubricating equipment. All the die tips of the MRD were disposed of simultaneously. Finite element analysis of the drawing process was performed according to the reduction ratio of each die tip, and the variables in drawing process with the MRD were optimized using a deep neural network to minimize the residual stress. Experiments on the drawing process with the conventional die and MRD were performed to evaluate the residual stress and verify the effectiveness of the MRD. The results of X-ray diffraction measurements indicated that the axial and hoop residual stresses on the surface were dramatically reduced. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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13 pages, 7349 KiB

Open AccessEditor’s ChoiceArticle

Multi-Stage Cold Forging Process for Manufacturing a High-Strength One-Body Input Shaft

by A Ra Jo, Myeong Sik Jeong, Sang Kon Lee, Young Hoon Moon and Sun Kwang Hwang

Materials 2021, 14(3), 532; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14030532 - 22 Jan 2021

Cited by 15 | Viewed by 7623

Abstract

A multi-stage cold forging process was developed and complemented with finite element analysis (FEA) to manufacture a high-strength one-body input shaft with a long length body and no separate parts. FEA showed that the one-body input shaft was manufactured without any defects or fractures. Experiments, such as tensile, hardness, torsion, and fatigue tests, and microstructural characterization, were performed to compare the properties of the input shaft produced by the proposed method with those produced using the machining process. The ultimate tensile strength showed a 50% increase and the torque showed a 100 Nm increase, confirming that the input shaft manufactured using the proposed process is superior to that processed using the machining process. Thus, this study provides a proof-of-concept for the design and development of a multi-stage cold forging process to manufacture a one-body input shaft with improved mechanical properties and material recovery rate. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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12 pages, 32411 KiB

Open AccessArticle

Design of Multi-Stage Roll Die Forming Process for Drum Clutch with Artificial Neural Network

by Jae-Hong Kim, Jae-Chang Ryu, Woo-Sik Jang, Joon-Hong Park, Young-Hoon Moon and Dae-Cheol Ko

Materials 2021, 14(1), 69; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14010069 - 25 Dec 2020

Viewed by 2110

Abstract

The multi-stage roll die forming (RDF) process is a plastic forming process that can manufacture a transmission part with a complex shape, such as a drum clutch, by using a die set with rotational rolls. However, it is difficult to satisfy dimensional accuracy because of spring-back and unfilling. The purpose of this study is to design a multi-stage RDF process for the manufacturing of a drum clutch to improve dimensional accuracy using an artificial neural network (ANN). Finite element (FE) simulation of the multi-stage RDF process is performed to predict the dimensional accuracy according to various clearances for each stage. Moreover, the ANN is used to determine the relationship between the clearance and dimensional accuracy of the drum clutch to reduce the number of FE simulation. The results of the FE simulation and ANN are used to determine the optimal clearance for each stage of the RDF process. Finally, the drum clutch is fabricated using the determined conditions. The experimental results are in good agreement with the results of FE simulation from the aspect of outer diameter, inner diameter, thickness of outer tooth, thickness of inner tooth, and face thickness of tooth. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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12 pages, 38955 KiB

Open AccessArticle

Study on Effect of Shapes of Serration of Joining Plane on Joining Characteristics for the Aluminum–Steel Multi-Materials Press Joining Process

by In-Kyu Lee, Sung-Yun Lee, Sang-Kon Lee, Myeong-Sik Jeong, Bong-Joon Kim and Won-Gwang Joo

Materials 2020, 13(24), 5611; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13245611 - 09 Dec 2020

Cited by 2 | Viewed by 1546

Abstract

Recently, mechanical joining processes have received much attention for joining multi-materials. In particular, these processes have a great demand in the automobile industry for weight reduction. The press-fitting process is a representative mechanical joining process. In this process, the shape of the interfacial serration on the joining plane is very important because it has a significant effect on the joining strength. In this study, the characteristics of the aluminum–steel press joining process were investigated according to the shape of the interfacial serration of the joining plane. The deformation of the material and the forming load were investigated by conducting finite element analysis. In addition, the unfilled height of the material, joining force, and torque were measured experimentally. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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19 pages, 11441 KiB

Open AccessArticle

A Combined Cold Extrusion for a Drive Shaft: A Parametric Study on Tool Geometry

by Tae-Wan Ku

Materials 2020, 13(10), 2244; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13102244 - 13 May 2020

Cited by 12 | Viewed by 3046

Abstract

Parametric investigations related to shoulder angle on tool geometry for a combined cold extrusion of a drive shaft, which consisted of spur gear and internal spline structures, were conducted through three-dimensional FE (finite element) simulations. The drive shaft was required to be about 92.00 mm for the face width of the top land on the spur gear part and roughly 22.70 mm for the groove depth of the internal spline section. AISI 1035 carbon steel material with a diameter of 50.00 mm and a length of 121.00 mm was spheroidized and annealed, then used as the initial billet material. A preform as an intermediate workpiece was adopted to avoid the excessive accumulation of plastic deformation during the combined cold extrusion. Accordingly, the cold forging process involves two extrusion operations such as a forward extrusion and a combined extrusion for the preform and the drive shaft. As the main geometric parameters influencing the dimensional quality and the deformed configuration of the final product, the two shoulder angles of θ₁ and θ₂ for the preform forging and the combined extrusion were both considered to be appropriate at 30°, 45°, and 60°, respectively. Using nine geometric parameter combinations, three-dimensional finite element simulations were performed, and these were used to evaluate the deformed features and the geometric compatibilities on the spur gear structure and the internal spline feature. Based on these comparative evaluations using the numerically simulated results, it is shown that the dimensional requirements of the target shape can be satisfied with the shoulder angle combination of (45°, 45°) for (θ₁, θ₂). Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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15 pages, 8539 KiB

Open AccessArticle

An Experimental Study of the Frictional Properties of Steel Sheets Using the Drawbead Simulator Test

by Tomasz Trzepiecinski, Andrzej Kubit, Ján Slota and Romuald Fejkiel

Materials 2019, 12(24), 4037; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12244037 - 04 Dec 2019

Cited by 7 | Viewed by 2340

Abstract

This article presents the results of an experimental investigation of the frictional resistance arising in a drawbead during sheet metal forming. The frictional characterization of DC04 deep drawing quality steels commonly used in the automotive industry is carried out using a friction simulator. The effects of some parameters of the friction process on the value of the coefficient of friction have been considered in the experimental investigations. The friction tests have been conducted on different strip specimens, lubrication conditions, heights of drawbead and specimen orientations in relation to the sheet rolling direction. The results of drawbead simulator tests demonstrate the relationship that the value of the coefficient of friction of the test sheets without lubrication is higher than in the case of lubricated sheets. The lubricant reduces the coefficient of friction, but the effectiveness of its reduction depends on the drawbead height and lubrication conditions. Moreover, the effectiveness of the reduction of the coefficient of friction by the lubricant depends on the specimen orientation according to the sheet rolling direction. In the drawbead test, the specimens oriented along the rolling direction demonstrate a higher value of coefficient of friction when compared to the samples cut transverse to the rolling direction. The smaller the width of the specimen, the lower the coefficient of friction observed. The difference in the coefficient of friction for the extreme values of the widths of the specimens was about 0.03–0.05. The use of machine oil reduced the coefficient of friction by 0.02–0.03 over the whole range of drawbead heights. Heavy duty lubricant even reduced the frictional resistances by over 50% compared to dry friction conditions. The effectiveness of friction reduction by machine oil does not exceed 30%. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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13 pages, 13969 KiB

Open AccessArticle

Prediction of Effective Strain Distribution in Two-Pass Drawn Wire

by Sang-Kon Lee, In-Kyu Lee, Sung-Min Lee and Sung-Yun Lee

Materials 2019, 12(23), 3923; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12233923 - 27 Nov 2019

Cited by 6 | Viewed by 2623

Abstract

In the multi-pass wire drawing process, the diameter of a wire is decreased by continuously passing it through progressively smaller drawing dies. Although the deformation depends on the process variables, in most wire drawing processes, the wire deformation is concentrated on the surface by its direct contact with the drawing dies, causing a nonlinear distribution of radial direction effective strain from the center to the surface. In this study, a new model for predicting this effective strain in two-pass drawn wire was derived based on the upper bound method, and a finite element analysis and drawing experiment were conducted to validate its effectiveness. The proposed model offers a promising approach to determining and thus controlling the strain in multi-pass drawn wire. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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21 pages, 13220 KiB

Open AccessArticle

Thermo-Mechanical Coupling Analyses for Al Alloy Brake Discs with Al₂O₃-SiC_(3D)/Al Alloy Composite Wear-Resisting Surface Layer for High-Speed Trains

by Lan Jiang, Yanli Jiang, Liang Yu, Hongliang Yang, Zishen Li and Youdong Ding

Materials 2019, 12(19), 3155; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12193155 - 27 Sep 2019

Cited by 14 | Viewed by 3415

Abstract

In the present work, a theoretical model of three-dimensional (3D) transient temperature field for Al alloy brake discs with Al₂O₃-SiC_(3D)/Al alloy wear-resisting surface layer was established. 3D transient thermo-stress coupling finite element (FE) and computational fluid dynamic (CFD) models of the brake discs was presented. The variation regularities of transient temperature and internal temperature gradient of the brake discs under different emergency braking conditions were obtained. The effects of initial braking velocity (IBV) and thickness of Al₂O₃-SiC_(3D)/Al alloy composite wear-resisting layer on the maximum friction temperature evolution of the disc were discussed. The results indicated the lower temperature and thermal stress distributed uniformly on the wear-resisting surface, which was dominated by high conductivity and cooling ability of the Al alloy brake disc. The maximum friction temperature was not obviously affected by the thickness of the wear-resisting layer. The maximum friction temperature of the brake discs increased with the increase of the IBV, the maximum friction temperature and thermal stress of the brake discs is about 517 °C and 192 MPa at IBV = 97 m/s considering air cooling, respectively. The lower thermal stress and fewer thermal cracks are produced during the braking process, which relatively decrease the damage. The friction behavior of the tribo-couple predicted using FE method correlated well with the experimental results obtained by sub-scale testing. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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12 pages, 7213 KiB

Open AccessArticle

Effect of Quenching Tempering-Post Weld Heat Treatment on the Microstructure and Mechanical Properties of Laser-Arc Hybrid-Welded Boron Steel

by Ho Won Lee, Kwang Jae Yoo, Minh Tien Tran, In Yong Moon, Young-Seok Oh, Seong-Hoon Kang and Dong-Kyu Kim

Materials 2019, 12(18), 2862; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12182862 - 05 Sep 2019

Cited by 4 | Viewed by 2971

Abstract

In the present study, we have investigated the effect of post-welding heat treatment (PWHT) of quenching and tempering (QT) on the microstructure and mechanical properties of welded boron steel joints processed using laser-arc hybrid welding on two commercial filler materials, SM80 (Type-I) and ZH120 (Type-II). The microstructure and mechanical properties of the weld joints were characterized via optical microscopy, Vickers microhardness, and the uniaxial tensile test. The macrostructure of the weld joint was composed of a fusion zone (FZ), heat-affected zone (HAZ), and base metal zone (BMZ). After the QT-PWHT, the QT specimens revealed the V-shape hardness distribution across the weld joint, while the as-welded specimen exhibited the M-shape hardness distribution. As a result, the QT specimens revealed the premature fracture with little reduction in the area at the interface between the HAZ and FZ, while the as-welded specimen exhibited the local necking and rupture in the BMZ. In addition, the Type-II filler material with a greater value of equivalent carbon content was rarely influenced by the tempering, maintaining its hardness in the as-quenched status, while the Type-I filler material showed a gradual decrease in hardness with the tempering time. The results demonstrate that the Type-II weld joint outperformed the Type-I weld joint in terms of the structural integrity of welded parts. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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12 pages, 4488 KiB

Open AccessArticle

Design of Lightweight CFRP Automotive Part as an Alternative for Steel Part by Thickness and Lay-Up Optimization

by Jeong-Min Lee, Byeong-Jin Min, Joon-Hong Park, Dong-Hwan Kim, Byung-Min Kim and Dae-Cheol Ko

Materials 2019, 12(14), 2309; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12142309 - 19 Jul 2019

Cited by 34 | Viewed by 3707

Abstract

Mechanical properties, such as strength and stiffness, of laminated carbon fiber reinforced plastic (CFRP) are generally affected by the lay-up method. However, no precise design rules to replace steel products with CFRP have been established that satisfy these properties. Therefore, this study proposes a set of rules to design automotive parts with equivalent bending stiffness through structural analysis and genetic algorithms (GAs). First, the thickness of the CFRP product was determined by comparing the bending deformation of steel products by structural analysis. To minimize the orthotropic characteristics of CFRP, the quasi-isotropic lay-up method was implemented to determine the thickness. Next, the lay-up angle was determined using GAs. The optimized lay-up angle of the CFRP product with minimum bending deformation was determined by population generation, cross-over, mutation, and fitness evaluation. CFRP B-pillar reinforcement was fabricated using the determined conditions and the bending deformation of the single component was evaluated. Finally, the B-pillar assembled with CFRP reinforcement was investigated by the drop tower test. Full article

(This article belongs to the Special Issue Metal Forming: Fundamentals, Simulation and Applications)

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