I. Czinege

6507113873

Publications - 11

Application of artificial neural networks for characterisation of formability properties of sheet metals

Dóra Harangozó I. Czinege

Publication Name: International Journal of Lightweight Materials and Manufacture

Publication Date: 2024-01-01

Volume: 7

Issue: 1

Page Range: 37-44

Description:

Artificial neural network models were developed to estimate forming limit diagrams from tensile test results based on our own experiments and data from the literature for steel and aluminium sheet metals. Experimental data were obtained from tensile tests and Nakazima tests. The input parameters used in the models were yield strength, ultimate tensile strength, uniform elongation, elongation at fracture, anisotropy coefficient and hardening exponent or combinations of these. The forming limit curves were defined by the measured minor and major strains using seven standard test specimens. After training the artificial neural network, the difference between measured and predicted results was evaluated by linear regression parameters and by the absolute errors. For steel sheet data taken from the literature, the estimated outputs of ANN models were compared with the results of empirical formulae developed by different authors. It was found that there was a high correlation coefficient between predicted and measured values for models using neural networks, which gave better approximations than other linear and non-linear models.

Open Access: Yes

DOI: 10.1016/j.ijlmm.2023.08.003

Comparative Evaluation of Forming Limit Curve Models for AlMg Alloys †

Dóra Harangozó I. Czinege

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

This publication deals with the comparative analysis of theoretical and empirical models suitable for predicting forming limit curves in the case of aluminum–magnesium alloys. The Stören–Rice and Hill–Bressan–Williams equations were evaluated and justified by inverse parameter identification. They showed good agreement with the measured strain values. Using the graphical Modified Maximum Force Criterion, it was demonstrated that the Voce hardening law is more suitable than the Swift one for characterizing this group of alloys, but the weighted combination of the two hardening laws is preferable.

Open Access: Yes

DOI: 10.3390/engproc2024079005

Effect of Roller Levelling on Tensile Properties of Aluminum Sheets

Dóra Harangozó I. Czinege

Publication Name: Materials

Publication Date: 2023-04-01

Volume: 16

Issue: 8

Page Range: Unknown

Description:

The straightening of sheets, bars and profiles plays an important role in many machining processes. The aim of sheet straightening in the rolling mill is to ensure that the deviation of sheets from flatness is within the tolerances specified in the standards or delivery conditions. There is a wide range of information available on the roller levelling process used to meet these quality requirements. However, little attention has been paid to the effects of levelling, namely the change in properties of the sheets before and after roller levelling. The aim of the present publication is to investigate how the levelling process affects tensile test results. The experiments have shown that levelling increases the yield strength of the sheet by 14–18%, while it decreases its elongation by 1–3% and hardening exponent by 15%. The mechanical model developed allows changes to be predicted, so that a plan can be made regarding roller levelling technology that has the least effect on the properties of the sheet while maintaining the desired dimensional accuracy.

Open Access: Yes

DOI: 10.3390/ma16083001

Characterisation of Inhomogeneous Plastic Deformation of AlMg Sheet Metals during Tensile Tests

Szabolcs Szalai Dóra Harangozó I. Czinege

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2020-08-25

Volume: 903

Issue: 1

Page Range: Unknown

Description:

The Portrevin-Le-Chatelier (PLC) effect was analysed quantitatively in the selected AlMg alloys with Mg-content between 2,8-4,6%. The propagation and characteristics of PLC bands were detected by digital image correlation (DIC) technique and the parameters of the bands were evaluated from strain distributions of tensile test specimens. In parallel, stress-strain curves were analysed evaluating stress serrations. The numerically defined parameters of changes in stress and strain were used for characterising the PLC effect on the behaviour of different sheet metals. General statements of literature were numerically proven for the tested materials and the effect of magnesium content on stress amplitude was analysed in detail.

Open Access: Yes

DOI: 10.1088/1757-899X/903/1/012023

Mass optimization of gears

I. Czinege

Publication Name: Periodica Polytechnica Mechanical Engineering

Publication Date: 2019-01-01

Volume: 63

Issue: 2

Page Range: 75-79

Description:

The paper deals with the mass optimization of gear pairs. The proposed material science based selection strategy uses an extended version of Ashby model, where the minimum value of mass as function of material parameters and density can be calculated. Comparative analyses have proved that applying the method proposed, various gear materials can be classified and ranked. It could be concluded that case or induction hardened steels and titanium alloys with appropriate surface treatment are the best solutions for high quality gear materials. The presented relationships for material parameters and geometry of gears help empirical or heuristic selection of proper materials.

Open Access: Yes

DOI: 10.3311/PPme.11648

Comparative study of the application of steels and aluminium in lightweight production of automotive parts

I. Czinege Miklos Tisza

Publication Name: International Journal of Lightweight Materials and Manufacture

Publication Date: 2018-12-01

Volume: 1

Issue: 4

Page Range: 229-238

Description:

The automotive industry has a decisive role in the economy of developed countries. Sheet metal forming – as one of the main processes in car manufacturing – has similarly important role. Concerning the recent trends in car production, the application of lightweight constructions principles is the main priority to meet customers' demands and the increased legal requirements. To meet these expectations, the application of high strength materials is regarded as one of the most promising possibilities. Applying high strength materials – beside high strength steels like DP1000, TRIP780 recently aluminium alloys, e.g. AA7021 or AA7075 – have a positive response for many of the requirements: increasing strength results in the application of thinner sheets together with significant mass reduction, leading to lower consumption with increased environment protection; however it can often lead to the decrease of formability, too. In this paper, an introduction on recent material developments in the automotive industry concerning both the use of new generation high strength steels and light metals with particular emphasis on aluminium alloys will be given. A comparison between steel and aluminium application in the automotive industry is given from various points of view. Since our main topic is the sheet metal forming, in this paper the body-in-white manufacturing in the automotive industry is the primary focus field.

Open Access: Yes

DOI: 10.1016/j.ijlmm.2018.09.001

Digital image analysis of sheet metal testing and forming

Szabolcs Szalai I. Czinege

Publication Name: 15th Imeko Tc10 Workshop on Technical Diagnostics 2017 Technical Diagnostics in Cyber Physical Era

Publication Date: 2017-01-01

Volume: Unknown

Issue: Unknown

Page Range: 176-180

Description:

Digital image analysing methods are widely used for evaluating local deformations in sheet metal tests and forming processes. The paper is focusing on tensile tests of uniform and non-uniform width flat specimens made of aluminum alloys, which are suitable for demonstrating Löders strain, Portevin-Le Chatelier (PLC) effect and for determination of Forming Limit Curve. Tests were carried out using GOM-ARAMIS® digital image analysis hardware and software. Observation of local deformations during tensile tests showed that initiation and evolution of local strains depend on the position of specimens related to rolling direction of sheet. Using non-uniform width specimens the local deformations are concentrated on the smallest cross-section in the final stage of tensile test. The measured major and minor strains give points of FLC.

Open Access: Yes

DOI: DOI not available

Modeling of distribution of visible and non-visible graphite nodules embedded in the surface layer of ductile cast iron

Ágnes Csizmazia I. Czinege Mihaly Réger T. Reti

Publication Name: Materials Science Forum

Publication Date: 2010-01-01

Volume: 659

Issue: Unknown

Page Range: 453-458

Description:

The graphite nodule count and size distribution are important structural parameters in the quantitative characterization of the microstructure of ductile cast irons. In several cases, it is observed that local surface damages (cracks or microchip formations) are generated by the final manufacturing process (superfinishing operation), and these defects are originated basically from the hidden (invisible) graphite nodules located directly below surface. Based on measured data obtained by an image analyzer, a stereological model and a simulation algorithm have been developed to analyse the correspondances between the graphite morphology and the defect formation. This method makes it possible to establish a correlation between the microstructure parameters and the occurrence of local surface defects on ductile cast iron components. © (2010) Trans Tech Publications.

Open Access: Yes

DOI: 10.4028/www.scientific.net/MSF.659.453

Selection of tool materials for cold forming operations using a computerized decision support system

J. Gram I. Czinege I. Felde T. Reti D. Y. Ju

Publication Name: Proceedings of the 17th Ifhtse Congress

Publication Date: 2008-01-01

Volume: 2

Issue: Unknown

Page Range: 773-775

Description:

A computerized decision support system (DSS) is outlined which is designated primarily to selcct the proper tool steel grades for various cold forming operations. This computerized system contains four data base: data base of cold forming operations and tools, of work materials, of cold forming tool materials and of wear resistant PVD coatings. The decision strategy makes it possible to select appropriate tool materials taking into consideration their most important material properties (wear resistance, toughness, compressive yield strength, tempering resistance, dimensional stability, machinability, and material price). The practical advantages of the developed decision support system are demonstrated on example.

Open Access: Yes

DOI: DOI not available

On the temperature rate dependent transformation processes

L. Costa I. Czinege I. Felde T. Reti R. Colas

Publication Name: Materials Science Forum

Publication Date: 2007-01-01

Volume: 537-538

Issue: Unknown

Page Range: 571-578

Description:

Kinetic models of new types are suggested which are designated primarily to predict the progress of non-isothermal transformations occurring during rapid heating and cooling in alloys. A common feature of each model outlined is that it takes into account not only the varying temperature but also the rate of temperature change on the transformation rate of the process. The two models represented by differential equations are generated by using the concept of virtual kinetic parameters, which can be determined from non-isothermal experiments only. A key property of the virtual parameter "p" involved in the transformation rate equations is that it quantitatively characterizes the temperature rate dependence of the non-isothermal reaction.

Open Access: Yes

DOI: 10.4028/0-87849-426-x.571

A novel approach of quenchant evaluation by applying quality functions

I. Czinege B. Smoljan I. Felde R. Colas

Publication Name: Materials Science Forum

Publication Date: 2007-01-01

Volume: 537-538

Issue: Unknown

Page Range: 513-518

Description:

A novel numerical approach for testing and evaluation of quenching media and quenching systems is outlined. The technique proposed is based on determination of heat transfer coefficient from temperature signals recorded and applying it as input for simulation of quenching process. The evaluation method is based on the calculated microstructural and mechanical properties of cylindrical samples.

Open Access: Yes

DOI: 10.4028/0-87849-426-x.513