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Forming Processes of Modern Metallic Materials

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A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Casting, Forming and Heat Treatment".

Deadline for manuscript submissions: closed (1 May 2020) | Viewed by 72663

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Dr. Tomasz Trzepieciński

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Department of Manufacturing Processes and Production Engineering, Rzeszow University of Technology, Al. Powst. Warszawy 8, 39-959 Rzeszów, Poland
Interests: anisotropic plasticity; computational modeling; constitutive modeling; finite element method (FEM); friction; friction welding; manufacturing processes; sheet metal forming; tribology
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Special Issue Information

Dear Colleagues,

I would like to call to your attention the Special Issue of Metals on the "Forming Processes of Modern Metallic Materials". The plastic forming of metallic materials is the most efficient and an important manufacturing technology in today's industry. Lightweight materials, such as titanium alloys, aluminium alloys and ultra-high-strength steels are used extensively in the automotive, aerospace, transportation, and construction industries leading to increasing demand for advanced innovative forming technologies. Today, numerical simulation is highly focused and provides a better understanding of the innovative forming processes. Computational methods and numerical analysis coupled with the modelling of the structural evolution allow us to reduce time and eliminate experimental tests.

The aim of this Special Issue is to present the latest achievements in various modern metal forming processes and the latest research related to the computational methods for metal forming technologies. Research articles focusing on new developments in the forming of metallic materials are welcome for consideration of publication. I truly believe that this Special Issue will help the metals research community to enhance understanding of the present status and trends of the forming processes of modern metallic materials. Topics of interest include, but are not limited to:

aerospace and automotive metal forming technologies,
computational techniques for metal forming processes,
high-speed forming technologies,
technology of incremental sheet forming,
formability of metallic materials,
hydroforming processes,
friction and lubrication in metal forming,
material behavior modeling of metal forming processes.

Prof. Tomasz Trzepiecinski
Guest Editor

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Keywords

Computational methods
Constitutive modeling
Finite element method
Formability
Friction
Metal forming
Metals
Microstructure
Sheet metal forming

Published Papers (13 papers)

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Editorial

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4 pages, 166 KiB

Open AccessEditorial

Forming Processes of Modern Metallic Materials

by Tomasz Trzepieciński

Metals 2020, 10(7), 970; https://doi.org/10.3390/met10070970 - 18 Jul 2020

Cited by 3 | Viewed by 2402

Abstract

The plastic working of metallic materials is one of the most efficient and important manufacturing technologies used in industry today [...] Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

Research

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16 pages, 7601 KiB

Open AccessArticle

A Comparative Assessment of Six Machine Learning Models for Prediction of Bending Force in Hot Strip Rolling Process

by Xu Li, Feng Luan and Yan Wu

Metals 2020, 10(5), 685; https://doi.org/10.3390/met10050685 - 22 May 2020

Cited by 28 | Viewed by 4285

Abstract

In the hot strip rolling (HSR) process, accurate prediction of bending force can improve the control accuracy of the strip crown and flatness, and further improve the strip shape quality. In this paper, six machine learning models, including Artificial Neural Network (ANN), Support Vector Machine (SVR), Classification and Regression Tree (CART), Bagging Regression Tree (BRT), Least Absolute Shrinkage and Selection operator (LASSO), and Gaussian Process Regression (GPR), were applied to predict the bending force in the HSR process. A comparative experiment was carried out based on a real-life dataset, and the prediction performance of the six models was analyzed from prediction accuracy, stability, and computational cost. The prediction performance of the six models was assessed using three evaluation metrics of root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R²). The results show that the GPR model is considered as the optimal model for bending force prediction with the best prediction accuracy, better stability, and acceptable computational cost. The prediction accuracy and stability of CART and ANN are slightly lower than that of GPR. Although BRT also shows a good combination of prediction accuracy and computational cost, the stability of BRT is the worst in the six models. SVM not only has poor prediction accuracy, but also has the highest computational cost while LASSO showed the worst prediction accuracy. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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18 pages, 23561 KiB

Open AccessArticle

Fatigue Life Assessment of Refill Friction Stir Spot Welded Alclad 7075-T6 Aluminium Alloy Joints

by Andrzej Kubit, Mateusz Drabczyk, Tomasz Trzepiecinski, Wojciech Bochnowski, Ľuboš Kaščák and Jan Slota

Metals 2020, 10(5), 633; https://doi.org/10.3390/met10050633 - 13 May 2020

Cited by 13 | Viewed by 2593

Abstract

Refill Friction Stir Spot Welding (RFSSW) shows great potential to be a replacement for single-lap joining techniques such as riveting or resistance spot welding used in the aircraft industry. In this paper, the fatigue behaviour of RFSSW single-lap joints is analysed experimentally in lap-shear specimens of Alclad 7075-T6 aluminium alloy with different thicknesses, i.e., 0.8 mm and 1.6 mm. The joints were tested under low-cycle and high-cycle fatigue tests. Detailed observations of the fatigue fracture characteristics were conducted using a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The locations of fatigue failure across the weld, fatigue crack initiation, and propagation behaviour are discussed on the basis of the SEM analysis. The possibility of predicting the propagation of fatigue cracks in RFSSW joints is verified based on Paris’s law. Two fatigue failure modes are observed at different load levels, including shear fracture mode transverse crack growth at high stress-loading conditions and at low load levels, and destruction of the lower sheet due to stretching as a result of low stress-loading conditions. The analysis of SEM micrographs revealed that the presence of aluminium oxides aggravates the inhomogeneity of the material in the weld nugget around its periphery and is a source of crack nucleation. The results of the fatigue crack growth rate predicted by Paris’s law were in good agreement with the experimental results. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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17 pages, 4384 KiB

Open AccessArticle

Effect of Lubrication on Friction in Bending under Tension Test-Experimental and Numerical Approach

by Tomasz Trzepiecinski and Hirpa G. Lemu

Metals 2020, 10(4), 544; https://doi.org/10.3390/met10040544 - 23 Apr 2020

Cited by 9 | Viewed by 3442

Abstract

This paper is aimed to determine the value of coefficient of friction (COF) at the rounded edge of the die in the sheet metal forming operations using the bending under tension (BUT) test. The experimental part of the investigations is devoted to the study of the frictional resistances of low alloy steel sheet under different strains of the specimen, surface roughnesses of the tool and for different lubrication conditions. Three oils are destined for different conditions of duties in the stamping process. Numerical modeling of the material flow in the BUT test has been conducted in the MSC.Marc program. One of the objectives of the numerical computations is to know the type of the contact pressure acting on the cylindrical surface countersample in the BUT test by assuming the anisotropic properties of the metallic sheet. It has been found that the COF in the rounded edge of the die does not vary with increasing sheet elongation. Taking into account that normal pressure increases with increasing specimen elongation and workpiece material is subjected to strain hardening phenomenon, the COF value is very stable during the friction test. The effectiveness of the lubrication depends on the balance between two mechanisms accompanied by friction process: roughening of workpiece asperities and adhesion of the contacting surfaces. In the case of high surface roughness of tool due to a dominant share of ploughing, all of the lubricants used were not able to decrease the COF in a sufficient extent. The used lubricants were able to reduce the value of friction coefficient approximately by 3–52% in relation to the surface roughness of rolls. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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20 pages, 10547 KiB

Open AccessArticle

Residual Stresses and Surface Roughness Analysis of Truncated Cones of Steel Sheet Made by Single Point Incremental Forming

by Ján Slota, Bogdan Krasowski, Andrzej Kubit, Tomasz Trzepiecinski, Wojciech Bochnowski, Kazimiera Dudek and Miroslav Neslušan

Metals 2020, 10(2), 237; https://doi.org/10.3390/met10020237 - 10 Feb 2020

Cited by 11 | Viewed by 3707

Abstract

The dimensional accuracy and mechanical properties of metal components formed by the Single Point Incremental Forming (SPIF) process are greatly affected by the prevailing state of residual stress. An X-ray diffraction method has been applied to achieve an understanding of the residual stress formation caused by the SPIF process of deep drawing a quality steel sheet drawpiece. The test object for an analysis of residual stress distribution was a conical truncated drawpiece with a slope angle of 71° and base diameter of the cone of 65 mm. The forming process has been carried out on a 3-axis HAAS TM1P milling machine. Uniaxial tensile tests have been carried out in the universal tensile testing machine to characterize the material tested. It was found that the inner surface of the drawpiece revealed small linear grooves as a result of the interaction of the tool tip with the workpiece. By contrast, the outer surface was free of grooves which are a source of premature cracking. The stress profile exhibits a nonlinear distribution due to different strengthening of the material along the generating line of the truncated conical drawpiece. The SPIF parts experienced a maximum residual stress value of about 84.5 MPa. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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14 pages, 5147 KiB

Open AccessArticle

Microstructure and Texture Evolution with Relation to Mechanical Properties of Compared Symmetrically and Asymmetrically Cold Rolled Aluminum Alloy

by Jakob Kraner, Peter Fajfar, Heinz Palkowski, Goran Kugler, Matjaž Godec and Irena Paulin

Metals 2020, 10(2), 156; https://doi.org/10.3390/met10020156 - 21 Jan 2020

Cited by 17 | Viewed by 4039

Abstract

The impact of asymmetric cold rolling was quantitatively assessed for an industrial aluminum alloy AA 5454. The asymmetric rolling resulted in lower rolling forces and higher strains compared to conventional symmetric rolling. In order to demonstrate the positive effect on the mechanical properties with asymmetric rolling, tensile tests, plastic-strain-ratio tests and hardness measurements were conducted. The improvements to the microstructure and the texture were observed with a light and scanning electron microscope; the latter making use of electron-backscatter diffraction. The result of the asymmetric rolling was a much lower planar anisotropy and a more homogeneous metal sheet with finer grains after annealing to the soft condition. The increased isotropy of the deformed and annealed aluminum sheet is a product of the texture heterogeneity and reduced volume fractions of separate texture components. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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11 pages, 6060 KiB

Open AccessArticle

Deformation Behavior and Experiments on a Light Alloy Seamless Tube via a Tandem Skew Rolling Process

by Feilong Mao, Fujie Wang, Yuanhua Shuang, Jianhua Hu and Jianxun Chen

Metals 2020, 10(1), 59; https://doi.org/10.3390/met10010059 - 29 Dec 2019

Cited by 13 | Viewed by 3881

Abstract

As a process for producing seamless tubes, the tandem skew rolling (TSR) process was proposed. In order to study deformation characteristics and mechanism on tubes obtained by the TSR process, a numerical simulation of the process was analyzed using Deform-3D software. Simulation results demonstrated the distribution of stress, strain, velocity, and temperature of a seamless tube in the stable stage during the TSR process. Actual experiments of carbon steel 1045, high strength steel 42CrMo, and magnesium alloy AZ31 were carried out in a TSR testing mill. The results demonstrated that the TSR process is qualified for producing tubes of high quality, with an accuracy of ±0.2 mm in wall thickness and ±0.35 mm in diameter. This process is suitable for manufacturing seamless tubes that are difficult to deform or that have been deformed in a narrow range of temperature. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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15 pages, 8103 KiB

Open AccessArticle

A 3D FEM-Based Numerical Analysis of the Sheet Metal Strip Flowing Through Drawbead Simulator

by Tomasz Trzepiecinski and Romuald Fejkiel

Metals 2020, 10(1), 45; https://doi.org/10.3390/met10010045 - 25 Dec 2019

Cited by 4 | Viewed by 3435

Abstract

Drawbeads are elements of the stamping die and they are used to compensate material flow resistance around the perimeter of the drawpiece or to change the stress state in specific regions of the drawpiece. This paper presents the results of experimental and numerical analyses of tests of sheet metal flowing through a drawbead. The tests have been carried out using a special tribological simulator of the drawbead. Experimental tests to determine the coefficient of friction (COF) have been carried out for three widths of sheet metal strip and two drawbead heights. The three-dimensional (3D) elastic-plastic numerical computations were performed using the MSC. Marc program. Special attention was given to the effect of material flow through the drawbead on the distribution of the normal stress on the tool-sheet interface. The mesh sensitivity analysis based on the value of the drawing force of the specimen being pulled through the drawbead allowed an optimal mesh size to be determined. The errors between the numerically predicted values of the COF and the values experimentally determined ranged from about 0.95% to 7.1% in the cases analysed. In the case of a drawbead height of 12 mm, the numerical model overestimated the value of the COF for all specimen widths analysed. By contrast, in the case of a drawbead height of 18 mm, all experimentally determined friction coefficients are underestimated by Finite Element Method (FEM). This was explained by the different character of sheet deformation under friction and frictionless conditions. An increase in the drawbead height, with the same sheet width, increases the value of the COF. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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11 pages, 3734 KiB

Open AccessArticle

A Study of the Coefficient of Friction in Steel Sheets Forming

by Tomasz Trzepiecinski

Metals 2019, 9(9), 988; https://doi.org/10.3390/met9090988 - 06 Sep 2019

Cited by 33 | Viewed by 4217

Abstract

The aim of this paper was to compare the tribological properties of a deep drawing quality steel sheet using the three commonly used friction tests, i.e., the strip drawing test, draw bead test, and bending under tension test. All tests have been carried out using a specially designed friction simulator. The test material was a 0.8-mm-thick DC04 steel sheet, commonly used in the automotive industry. Uniaxial tensile tests have been carried out to characterise the mechanical properties of the specimens. Furthermore, measurements of the sheet surface topography have been carried out to characterise the tribological properties of the specimens. The friction tests have been conducted under different pressure and lubrication conditions, surface roughnesses of tools represented by counter-samples, and orientations of the specimens according to the direction of the sheet rolling. A comparative analysis of the results of the friction tests revealed different values of friction. In the strip drawing test, the value of the coefficient of friction decreases as the contact pressure increases for both dry and lubricated conditions. In the draw bead test, the specimens oriented along the rolling direction demonstrated a higher value of the coefficient of friction compared to the samples cut transverse to the rolling direction. In contrast to the strip drawing test, the specimens tested in the bending under tension test exhibit a tendency to an increase in the value of the coefficient of friction with the increasing contact pressure. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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15 pages, 5490 KiB

Open AccessArticle

Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

by Hyeong Min Heo, Jun Hwan Kim, Sung Ho Kim, Jong Ryoul Kim and Won Jin Moon

Metals 2019, 9(8), 904; https://doi.org/10.3390/met9080904 - 18 Aug 2019

Cited by 1 | Viewed by 2951

Abstract

In this study, the effect of heat treatment on the fracture behavior of alloy B steel with boron (B) contents as high as 130 ppm was investigated. The Alloy B are derived from Gr.92 steel with outstanding creep characteristics. The amounts of minor alloying elements such as B, N, Nb, Ta, and C were optimized to achieve better mechanical properties at high temperatures. Hence, workability of the alloy B and Gr.92 were compared. An increase in the B content affected the phase transformation temperature and texture of the steel. The development of the {111}<uvw> components in γ-fibers depended on the austenite fraction of the steel after the phase transformation. An increase in the B content of the steel increased its α-to-γ phase transformation temperature, thus preventing the occurrence of sufficient transformation under the normalizing condition. Cracks occurred at the point of the elastic-to-plastic deformation transition in the normal direction during the rolling process, thereby resulting in failure. Therefore, it is necessary to avoid intermediate heat treatment conditions, in which γ-fibers do not fully develop, i.e., to avoid an imperfect normalization. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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12 pages, 12000 KiB

Open AccessArticle

Springback Calibration of a U-Shaped Electromagnetic Impulse Forming Process

by Xiaohui Cui, Zhiwu Zhang, Hailiang Yu, Xiaoting Xiao and Yongqi Cheng

Metals 2019, 9(5), 603; https://doi.org/10.3390/met9050603 - 24 May 2019

Cited by 18 | Viewed by 3110

Abstract

A three-dimensional (3D) finite-element model (FEM), including quasi-static stamping, sequential coupling for electromagnetic forming (EMF) and springback, was established to analyze the springback calibration by electromagnetic force. Results show that the tangential stress at the sheet bending region is reduced, and even the direction of tangential stress at the bending region is changed after EMF. The springback can be significantly reduced with a higher discharge voltage. The simulation results are in good agreement with the experiment results, and the simulation method has a high accuracy in predicting the springback of quasi-static stamping and electromagnetic forming. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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Review

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53 pages, 17494 KiB

Open AccessReview

Recent Developments and Trends in Sheet Metal Forming

by Tomasz Trzepieciński

Metals 2020, 10(6), 779; https://doi.org/10.3390/met10060779 - 10 Jun 2020

Cited by 52 | Viewed by 23309

Abstract

Sheet metal forming (SMF) is one of the most popular technologies for obtaining finished products in almost every sector of industrial production, especially in the aircraft, automotive, food and home appliance industries. Parallel to the development of new forming techniques, numerical and empirical approaches are being developed to improve existing and develop new methods of sheet metal forming. Many innovative numerical algorithms, experimental methods and theoretical contributions have recently been proposed for SMF by researchers and business research centers. These methods are mainly focused on the improvement of the formability of materials, production of complex-shaped parts with good surface quality, speeding up of the production cycle, reduction in the number of operations and the environmental performance of manufacturing. This study is intended to summarize recent development trends in both the numerical and experimental fields of conventional deep-drawing, spinning, flexible-die forming, electromagnetic forming and computer-controlled forming methods like incremental sheet forming. The review is limited to the considerable changes that have occurred in the SMF sector in the last decade, with special attention given to the 2015–2020 period. The progress observed in the last decade in the area of SMF mainly concerns the development nonconventional methods of forming difficult-to-form lightweight materials for automotive and aircraft applications. In evaluating the ecological convenience of SMF processes, the tribological aspects have also become the subject of great attention. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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34 pages, 5809 KiB

Open AccessReview

Recent Developments and Trends in the Friction Testing for Conventional Sheet Metal Forming and Incremental Sheet Forming

by Tomasz Trzepiecinski and Hirpa G. Lemu

Metals 2020, 10(1), 47; https://doi.org/10.3390/met10010047 - 25 Dec 2019

Cited by 53 | Viewed by 9848

Abstract

Friction is the main phenomenon that has a huge influence on the flow behavior of deformed material in sheet metal forming operations. Sheet metal forming methods are one of the most popular processes of obtaining finished products, especially in aerospace, automobile, and defense industries. Methods of sheet forming are carried out at different temperatures. So, it requires tribological tests that suitably represent the contact phenomena related to the temperature. The knowledge of the friction properties of the sheet is required for the proper design of the conditions of manufacturing processes and tools. This paper summarizes the methods used to describe friction conditions in conventional sheet metal forming and incremental sheet forming that have been developed over a period of time. The following databases have been searched: WebofKowledge, Scopus, Baztool, Bielefield Academic Search Engine, DOAJ Directory of Open Access Journals, eLibrary.ru, FreeFullPdf, GoogleScholar, INGENTA, Polish Scientific Journals Database, ScienceDirect, Springer, WorldCat, WorldWideScience. The English language is selected as the main source of review. However, in a limited scope, databases in Polish and Russian languages are also used. Many methods of friction testing for tribological studies are selected and presented. Some of the methods are observed to have a huge potential in characterizing frictional resistance. The application of these methods and main results have also been provided. Parameters affecting the frictional phenomena and the role of friction have also been explained. The main disadvantages and limitations of the methods of modeling the friction phenomena in specific areas of material to be formed have been discussed. The main findings are as follows—The tribological tests can be classified into direct and indirect measurement tests of the coefficient of friction (COF). In indirect methods of determination, the COF is determined based on measuring other physical quantities. The disadvantage of this type of methods is that they allow the determination of the average COF values, but they do not allow measuring and determining the real friction resistance. In metal forming operations, there exist high local pressures that intensify the effects of adhesion and plowing in the friction resistance. In such conditions, due to the plastic deformation of the material tested, the usage of the formula for the determination of the COF based on the Coulomb friction model is limited. The applicability of the Coulomb friction model to determine the COF is also very limited in the description of contact phenomena in hot SMF due to the high shear of adhesion in total contact resistance. Full article

(This article belongs to the Special Issue Forming Processes of Modern Metallic Materials)

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