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EN
This study explores the creation of a complex, eight-vertex shape through a deep-drawing process using two distinct approaches. The first, known as the direct method, involves forming the desired shape directly from metal sheets. The second approach, referred to as the indirect method, requires an intermediate step where a cylindrical shape is initially drawn and then reshaped into the final complex form through a redrawing process. A comparison was conducted between the two methods to evaluate their performance in terms of drawing force, thickness distribution, as well as stress and strain behavior. Low-carbon steel (1008-AISI) sheets with a thickness of 0.7 mm and a diameter of 80 mm were utilized for the experiments. The simulation of these processes was carried out using ANSYS 18.0 software. The findings revealed that the maximum drawing force recorded during the direct drawing process was 41 KN (experimental) and 30 KN (finite element simulation). Additionally, the redrawing process led to an increase in effective stress and strain, reaching peak values of 835.23 MPa (stress) and 0.442 (strain, simulation) or 0.345 (strain, experimental) in the minor axis curvature region. The redrawing process also resulted in the most significant thinning of 7.143% (simulation) and 5.722% (experimental) at the same curvature zone. The direct drawing process, however, exhibited superior uniformity in thickness, stress, and strain distributions.
EN
Single point incremental Forming (SPIF) is a novel and practical approach for quickly prototyping and producing small batch sheet metal components. Predicting the impact of sheet thickness in the SPIF process is vital for assessing forming limits, understanding material behavior, optimizing tool design and path, and improving material utilization. It enables engineers to make informed decisions and optimize the process for enhanced formability and part quality. In this work, the numerical simulation of formability of the hyperbolic truncated pyramid with varying wall angles from 20° to 80° by the implementation of the “Hooputra Ductile Damage (HDD) model” in Abaqus/Explicit with the version of (CAE, 2017) has been conducted for brass of CuZn37 to study and predict the impact of the material's sheet thickness on its formability in SPIF process. In addition to that, the effect of sheet thickness on three other output responses: Von Mises stress, equivalent plastic strain, and contact pressure, have been examined. The results demonstrated the excellent success of the Hooputra Ductile Damage model in simulating the formability and capturing the fracture in the SPIF process with a total error ratio of approximately 1.91%. The results also showed that increasing sheet thickness from 0.4 – 1.4 mm increases formability, Von Mises stress, and contact pressure while leading to decreases and then increases the equivalent plastic strain.
EN
The deep drawing process for square cups is commonly utilized in sheet metal forming, however, there are many associated defects, including fracture, earing, wrinkling. A problem that has more attention in this work is the studying of the influence of the different parameters such as blank diameter, drawing speed, and punch profile radius on the formability of the squared cups. Three circular blanks with diameter (80, 90, 100) mm, three punch profile radius of (4, 7, 10) mm, and three drawing speed of (100, 200, 300) mm/min have been chosen, while the other parameters kept constant. The formability indicators utilized in this study are thickness distribution, maximum thinning and maximum drawing force. The experiments were designed by L9 Taguchi method and analyzed by ANOVA and S/N ratios techniques. The results shown that square cup corners experience higher deformation than that of the side walls cup. Consequently, during plastic deformation, the metal flows along the side walls of the cup are easier and more uniform compared to those in the corners. The best results were obtained from the 80mm blank dimeter, with 100mm/min drawing speed and 7mm punch profile radius according to the uniform thickness distribution, maximum thinning and maximum drawing force.
EN
The article discusses the influence of heat treatment and metal forming parameters on formability and the structure of the AZ91 cast magnesium alloy. The aim of the article is to determine the optimal parameters of homogenization and plastic deformation of sand castings made of the AZ91 alloy in order to improve their properties and structure. In this study, sand castings made from the AZ91 alloy were examined. In the first stage, the castings were homogenized at: 385°C, 400°C, 415°C and 430°C with argon as a shielding gas for 24 hours and then quenched. Subsequently the upsetting tests were conducted at 380 C; 400 C; 420 C; 440 C for two deformation values: ε=0.7 and ε=1.1. After upsetting, the samples were water- and air-cooled. At this stage, a visual assessment was made and samples without cracks were subjected supersaturation at 415 C for 6 h, and artificial aging at 175 C for 24 h. Vickers microhardness tests and microstructure assessment were carried out, at individual stages of testing. Based on the results obtained from the upsetting, structure and hardness tests, the most favorable homogenisation and plastic deformation conditions were determined for AZ91 alloy sand castings. The best results are achieved by homogenizing sand castings at 415 °C for 24 h. Among the tested parameters for conducting metal forming processing in the range of 380-440 °C and deformation values: ε=0.7 and ε=1.1, forging of sand-cast AZ91 magnesium alloy at 420 °C and deformation of ε=0.7 with water cooling seems to be the most favourable. The final heat treatment applied after the deformation process consists of supersaturation at 415 °C for 6 hours water quenching as artificial aging at 175 °C for 24. This combination of heat and plastic treatment parameters of castings allows for improvement of the structure and properties of sand castings made of the AZ91 alloy.
EN
This article presents the results of experimental tests on the stretch-forming ability of 0.21-mm-thick AW-5052-H28 aluminium alloy sheets used in the production of pull-off cups. Erichsen test under various tribological conditions (dry friction, lubrication with graphite lubricant) was used to assess the sheet formability. Punches with a various diameter of the spherical end (8 and 20 mm) were used in the tests. The effect of soaking conditions and varnishing variants on the value of Erichsen indices IE and IE11 was investigated. The sheets were soaked for 13 minutes at various temperatures: 185°C, 190°C and 200°C. In test conditions without lubrication, the lowest value of the IE index = 3.3 mm was observed for sheets in as-received state and for samples after soaking. However, the highest values of the Erichsen index in tests without lubrication were measured for varnished samples and repeatedly soaked. The tests conducted under lubrication conditions with graphite grease revealed usually higher values of the IE index compared to testing conditions without the use of grease. The values of the IE11 index were approximately twice lower than the IE indices. Observation of the bulge surface revealed a smooth surface, which means that the material is characterised by a fine-grained microstructure.
PL
W tym artykule przedstawiono wyniki badań eksperymentalnych odkształcalności blach ze stopu aluminium AW-5052-H28 o grubości 0.21 mm stosowanych do produkcji kapsli zawierających zawleczkę. Tłoczność blachy określono metodą Erichsena w warunkach tarcia suchego i smarowania smarem grafitowym. Wykorzystano stemple o średnicy sferycznej końcówki 8 oraz 20 mm. Badano wpływ warunków lakierowania i wygrzewania na wartość wskaźników Erichsena IE oraz IE11. Wygrzewanie blach przeprowadzano w czasie 13 minut i w różnej temperaturze: 185°C, 190°C oraz 200°C. W warunkach bez smarowania najmniejszą wartością wskaźnika IE = 3,3 mm charakteryzowały się blachy w stanie dostawy oraz próbki po wygrzewaniu. Natomiast najwyższe wartości wskaźnika Erichsena w badaniach bez smarowania zmierzono dla próbek lakierowanych oraz wielokrotnie wygrzewanych. Testy przeprowadzone w warunkach smarowania smarem grafitowym ujawniły przeważnie większe wartości wskaźnika IE w porównaniu do warunków testowania bez użycia smaru. Wartości wskaźnika IE11były około dwukrotnie mniejsze niż wskaźnika IE. Obserwacja powierzchni wytłoczenia pozwoliła stwierdzić gładką powierzchnię, co oznacza, że materiał charakteryzował się drobnoziarnistą mikrostrukturą.
EN
The article discusses the ductility and formability of ultrafine-grained 3003 aluminum alloy plates processed using incremental equal channel angular pressing. The influence of temperature and strain rate is evaluated by means of tensile tests and cupping tests under various conditions. It is reported that tensile elongation increases two-fold at elevated temperature, without excessive grain growth. With the right selection of processing conditions, the formability of the plate, expressed as cup height deformed in a cupping test, can be enhanced—as much as 62% compared with room temperature when the processing takes place at 150 °C. The improvement in ductility was attributed to a reduced apparent activation volume due to grain refinement, which translated into improved strain rate sensitivity.
EN
The single point incremental forming (SPIF) process is gaining special attention in the aerospace, biomedical and manufacturing industries for making intricate asymmetric components. In the present study, SPIF process has been performed for forming varied wall angle conical and pyramidal frustums using DP590 steel. Initially, the conventional stretch forming process has been performed for finding the fracture forming limit diagram (FFLD). Further, it has been validated with the limiting strains found using SPIF process. The conical and pyramidal frustums deformed near to the plane strain and biaxial region, respectively. The theoretical FFLD has been predicted using seven different ductile damage models. The effect of sheet anisotropy while predicting the fracture strains has been included using Hill 1948 and Barlat 1989 yielding functions. Among the used damage models, the Bao-Wierzbicki (BW) model along with Barlat 1989 yield criterion displayed the least error of 2.92% while predicting the fracture locus. The stress triaxiality in the different forming region has been thoroughly investigated and it has been found that the higher triaxiality value reveals high rate of accumulated damage which lead to early failure of the material in the respective region. The stress triaxiality and effective fracture strains have also been found to be significantly affected by the anisotropy. The micro-textural studies have also been performed and it has been found that the increase in local misorientations and shift in the textural components from γ-fiber to ε-fiber in the corner region of the frustums worked towards limiting the formability of material and ultimately leading towards the fracture of frustums.
EN
Layered metallic materials (LMMs) offer superior properties in comparison to their counterpart monolithic sheets. Single-point incremental forming (SPIF) has emerged as an economical solution to produce LMM parts. However, delamination can limit the formability of such parts. In this study, the delamination analysis during SPIF of layered sheets was performed. Steel/steel bi-layer sheets were fabricated by roll bonding. These sheets were produced at thickness reduction ratios of 47%, 58% and 70%. The bond strength and fracture toughness in mode I and mode II were determined by T-peel and tensile shear tests, respectively. When the thickness reduction ratio was increased from 47 to 70%, an increase in bond strength was observed with 572% increase in mode I and 15.6% in mode II, respectively. On the other hand, with the same percent increase in thickness reduction, the critical strain energy release showed an increase of 3992% in mode I and 20% decrease in mode II. Surface-based cohesive zone model was used to define the interface between layers during numerical simulation of SPIF for delamination analysis. To validate the numerical results, SPIF of given bi-layer sheet was performed experimentally and a good agreement between the numerical and experimental results was observed.
9
Content available remote Strefowa obróbka cieplna taśm stalowych tłoczonych na gorąco
PL
Rosnące zapotrzebowanie przemysłu motoryzacyjnego na elementy charakteryzujące się wysoką wytrzymałością oraz skomplikowanym kształtem doprowadziło do opracowania nowoczesnych technik kształtowania taśm na gorąco. Do tej grupy metod zaliczany jest proces strefowej obróbki cieplnej, który jest realizowany podczas tłoczenia. Pozwala on na uzyskanie elementów o skomplikowanym kształcie, charakteryzujących się strefowo zróżnicowanymi własnościami mechanicznymi.
EN
The growing demand of the automotive industry for elements characterized by high strength and complicated shape has led to the development of new techniques of steel sheets forming. This group of methods includes the tailored heat treatment process, which is carried out during stamping. It allows obtaining elements characterized by the complicated shape and tailored mechanical properties. The special dies used in the hot forming process and controlled cooling to obtain more favorable mechanical properties compared to cold-formed elements. The tailored hot stamping enables to reduce the thickness of elements responsible for the passenger passive safety leading to the reduction of vehicle total weight.
EN
The paper is focused on study of plasticity and formability of dual phase steel DP 450, which is used in automotive industry. The paper shows results from tensile test for plasticity determination and also results of technological tests for complex evaluation of formability. These consisted from Erichsen cup test, Fukui test and Schmidt test. The paper shows also results of microhardness measurement.
PL
Artykuł koncentruje się na badaniu plastyczności i odkształcalności stali dwufazowej DP 450, która jest stosowana w przemyśle motoryzacyjnym. W pracy przedstawiono wyniki prób rozciągania dla określenia plastyczności, a także wyniki testów technologicznych dla kompleksowej oceny odkształcalności. Składały się one z testu pucharowego Erichsena, testu Fukui i testu Schmidta. W pracy przedstawiono również wyniki pomiaru mikrotwardości.
EN
Compared with monolithic metal sheet, Single Point Incremental Forming (SPIF) of bimetal composite sheet has attracted increasing attention, as it takes advantages of materials with different superior properties, such as high strength, low density, and good corrosion resistance. However, deformation behaviors of bimetal composite sheet in SPIF may differ from the single-layer sheet, which depends on the layer arrangements and mechanical properties of each layer. In this regard, a comprehensive study was conducted to investigate the deformation behaviors of roll-bonded Cu-Al composite sheets in SPIF through predictive modeling, including analytical, empirical as well as numerical approaches, and extensive experimental work taking into consideration effects of key process parameters. It was demonstrated that overall, the formability, surface roughness, thickness variation and forming force in different layer arrangements, in terms of various process parameters, follow the similar trends to single-layer sheets. However, it was further revealed that deformation mode of layer-up sheet tends to a compression state and that of layer-down sheet tends to a stretching state. This leads to higher formability and larger forming force in Al/Cu layer arrangement compared to Cu/Al layer arrangement, as the exterior thinner but stronger Cu layer could endure more stretching deformation.
EN
Single point incremental forming (SPIF) is a flexible, innovative, and cheap process for rapidmanufacturing of complex sheet metal parts. It is a crucial task for engineers to predict aprocess when many independent parameters are affecting simultaneously its performance.An artificial neural network (ANN) based prediction model was developed to evaluateaverage surface roughness (Ra) and maximum forming angle (Ømax) while SPIF forming ofAA5052-H32 material. A feedforward backpropagation network with Levenberg–Marquardtalgorithm was employed to build ANN model. The ANNs (4-n-1, 4-n-2) were generated byintroducing different combinations of transfer functions and a number of neurons. Theconfirmation runs were performed to verify the agreement between the ANN predicted andthe experimental results. The developed ANN model (4-n-1) was capable of predicting theprocess response with an excellent accuracy and resulted in overall R-value, MSE, and MAPEof 0.99807, 0.0209, and 5.96% for Ra0.99913, 0.0281, and 0.003 for Ømax. The optimum 4-n-2model was built with overall R-value, MSE of 0.99999 and 0.057194, respectively. Hence, itwas found that the engineering efforts may be reduced in the SPIF process with successfulANN model implementation.
13
Content available remote Strefowa obróbka cieplna taśm stalowych tłoczonych na gorąco
PL
Rosnące zapotrzebowanie przemysłu motoryzacyjnego na elementy charakteryzujące się wysoką wytrzymałością oraz skomplikowanym kształtem doprowadziło do opracowania nowoczesnych technik kształtowania taśm na gorąco. Do tej grupy metod zaliczany jest proces strefowej obróbki cieplnej, który jest realizowany podczas tłoczenia. Pozwala on na uzyskanie elementów o skomplikowanym kształcie, charakteryzujących się strefowo zróżnicowanymi własnościami mechanicznymi. Zastosowanie specjalnych matryc do kształtowania na gorąco oraz kontrolowanego chłodzenia pozwala na uzyskanie bardziej korzystnych własności mechanicznych w porównaniu do elementów kształtowanych na zimno. Zastosowanie tej technologii pozwala na redukcję grubości ścianek elementów odpowiadających za bezpieczeństwo bierne pasażerów, prowadząc jednocześnie do redukcji masy całkowitej pojazdu.
EN
The growing demand of the automotive industry for elements characterised by high strength and complicated shape has led to the development of new techniques of steel sheets forming. This group of methods includes the tailored heat treatment process, which is carried out during stamping. It enables obtaining elements characterised by complicated shape and tailored mechanical properties. Special dies used in the hot forming process and controlled cooling enable obtaining more favorable mechanical properties as compared to cold-formed elements. Tailored hot stamping enables to reduce the thickness of elements responsible for passenger passive safety, which leads to the reduction of the vehicle total weight.
EN
The paper deals with laser welding and its influence on the strength and plastic properties of stainless steel AISI 304 and AISI 430. The microstructure of samples laser welded by solid state fiber laser YLS-5000, made of stainless steel sheets with thickness 0,7 mm were researched. The effect of laser power and welding speed on the mechanical properties were measured by tensile test on specimens with weld in longitudinal direction. Microstructure of laser weld, heat affected zone and base material was analysed on perpendicular direction to laser weld by light microscopy. As it has been found, only the minor effect of laser welding on the mechanical properties of the stainless steel AISI 304 was found. Otherwise, the major effect of laser welding on the mechanical properties of the stainless steel AISI 430has been recorded. Applied formability of stainless steels was researched by numerical simulation of hydroforming of fuel tank.
PL
Artykuł dotyczy spawania laserowego i jego wpływu na wytrzymałość i właściwości plastyczne stali nierdzewnej AISI 304 i AISI 430. Dokonano analizy mikrostruktury próbek zgrzewanych laserem włókna stałego YLS-5000 wykonanego z blach ze stali nierdzewnej o grubości 0,7 mm. Wpływ mocy lasera i szybkości spawania na właściwości mechaniczne mierzono w próbach rozciągania na próbkach ze spoiną w kierunku wzdłużnym. Mikrostrukturę połączenia laserowego, strefy wpływu ciepła i materiału podstawowy analizowano w kierunku prostopadłym do spawania za pomocą mikroskopu świetlnego. Stwierdzono jedynie niewielki wpływ spawania laserowego na właściwości mechaniczne stali nierdzewnej AISI 304. Natomiast odnotowano znaczący wpływ spawania laserowego na właściwości mechaniczne stali AISI 430. Odkształcalność stali nierdzewnej zbadano za pomocą numerycznej symulacji hydroformowania.
EN
This paper discusses experimental results concerning the plastic deformation of the bonding zone in a two-layer AZ31/Al material subjected to compression loads. The specimens were fabricated by diffusion bonding method. The 50 μm thick transition zone at the AZ31/Al interface contained Mg–Al intermetallic phases. The physical modelling of the deformation behaviour of the intermetallic zone was performed using a Gleeble 3800 system. The compression tests were carried out at two temperatures (300 and 400 °C), two strain rates (0.1 and 1.0 s−1) and a true strain of 0.15 applied in one or two stages. The metallographic examinations and microhardness measurements were performed to assess the influence of the selected process parameters on the forming behaviour of the intermetallic zone. The experiments revealed that the main factors affecting the formability of the intermetallic zone in the two-layer AZ31/Al material were the strain rate and the temperature. It was found that when the deformation occurred at a strain rate of 0.1 s−1 and a temperature of 400 °C, there was no loss of continuity of the intermetallic transition zone; such conditions induced its plasticization.
16
Content available remote Detection of strain localization in numerical simulation of sheet metal forming
EN
This paper presents an investigation on the detection of strain localization in numerical simulation of sheet metal forming. Two methods to determine the onset of localized necking have been compared. The first criterion, newly implemented in this work, is based on the analysis of the through-thickness thinning (through-thickness strain) and its first time derivative in the most strained zone. The limit strain in the second method, studied in the authors’ earlier works, is determined by the maximum of the strain acceleration. The limit strains have been determined for different specimens undergoing deformation at different strain paths covering the whole range of the strain paths typical for sheet forming processes. This has allowed to construct numerical forming limit curves (FLCs). The numerical FLCs have been compared with the experimental one. Mesh sensitivity analysis for these criteria has been performed for the selected specimens. It has been shown that the numerical FLC obtained with the new criterion predicts formability limits close to the experimental results so this method can be used as a potential alternative tool to determine formability in standard finite element simulations of sheet forming processes.
17
Content available remote High strength steels and aluminium alloys in lightweight body manufacturing
EN
Purpose: of this paper: The main objectives of this paper are to give an overview about the application of various kinds of high strength steels and aluminium alloys in the automotive industry to produce lightweight car body elements to achieve significant reductions in harmful emissions to provide more environmental friendly vehicles which simultaneously fulfils the increased safety requirements, too. In these respects, both high strength automotive steels (e.g. DP, TRIP, TWIP and HPF steels), as well as high strength aluminium alloys (e.g. AA6082, AA7075, etc.) are more and more widely applied in the vehicle manufacturing. Design/methodology/approach: The contradiction between the increased strength and lower formability of these high strength metallic materials is one of the main issues in their application in the automotive industry. Therefore, in this paper primary focus will be placed on the formability properties of these materials, concerning first of all the limits of formability in various cold and hot forming conditions. To fully utilize the potentials of these materials in forming processes the numerical modelling of forming with FEM simulation is of utmost importance. Findings: Recently in the automotive industry the Hot Press Forming of high strength boron-alloyed manganese steels become an industrially established process, while the Hot Forming and Quenching (HFQ) of artificially ageing high strength aluminium alloys now become the focus of scientific research. The paper will analyse the main process parameters and gives comparisons of automotive applications. Research limitations/implications: There are still certain shortages of industrial applications, namely the limits of economic cycle times for economical mass production which needs further research activities in these fields. Practical implications: Since both the materials mentioned above and the forming processes usually applied, furthermore the available benefits are extremely important for the automotive industry these results have significant practical involvement. Originality/value: The applied research methods and the introduced new findings will show the originality of the paper.
PL
W artykule przedstawiono problemy oceny tłoczności materiałów metalicznych, których odkształcalność jest ograniczona. Zdefiniowano pojęcie trudno odkształcalnych wsadów do tłoczenia dzięki zestawieniu i usystematyzowaniu przyczyn ograniczających tłoczność. Zaproponowano wytyczne postępowania przy ocenie tłoczności dla tego typu trudno odkształcalnych wsadów. Stosowana metodyka badawcza opiera się o wykorzystanie metod fizycznego i numerycznego modelowania proceu tłoczenia. W badaniach zastosowano systemy automatycznego analizatora odkształceń Auto Grid, a do modelowania numerycznego oprogramowanie ETA/Dynaform. Praca stanowi przekrojową analizę szeregu badań prowadzonych przez autorkę w zespole badaczym Instytutu Technologii Metali Politechniki Śląskiej przez ostatnich kilka lat.
EN
The article presents the drawability evaluation problems of metallic materials, which deformability is limited. There is defined the concept of hard deformable charges for pressing through the statement and systematize the reasons for restricting their drawability. The guidelines for the drawability assessment for such type difficult charges are proposed. The research methodology is based on the use of methods of physical and numerical modeling of the stamping process. Presented study used the automatic strains analyzer Auto Grid and numerical modeling software ETA / Dynaform. This work is a cross-sectional analysis of a series of studies conducted by the author in the research team of the Institute of Metal Technology Silesian University of Technology in the past few years.
19
Content available Formability of thin sheets from aluminum alloys
EN
In this contribution there have been evaluated properties of four types of sheets made from aluminium alloys. In the case of each of the examined sheets there has been checked its shearing ability via the influence of punch-die clearance change on the quality of blanking edge. Quality of blanking edge is characterized by a ratio of plastic zone height to the total thickness of the sheared material. Formability during the drawing process was measured with earring test. Results are presented by the earring coefficient (unequal height) of the cups.
PL
Redukcja masy samochodu jest możliwa jedynie dzięki kompleksowemu podejściu obejmującemu zastosowanie wysokowytrzymałych blach stalowych o strukturze wielofazowej oraz nowoczesnych technik łączenia i kształtowania. Coraz większe znaczenie zyskuje technologia tłoczenia wsadów spawanych laserowo typu tailored welded blanks, a także jej odmiany: tailored welded coils i tailored welded tubes. Metody te umożliwiają optymalizację tłoczenia blach na liczne elementy karoserii, co skutkuje obniżeniem masy pojazdu, zmniejszeniem liczby odpadów, części, wzmocnień, a w konsekwencji prowadzi do obniżenia kosztów wytwarzania.
EN
The reduction of a car’s weight is only possible due to a complex approach including the application of high-strength sheet steels with multiphase microstructures and modern joining and forming techniques. More and more attention is paid on stamping of laser-welded sheets using the tailored-welded blank technology and its modifications: tailored-welded coils and tailored-welded tubes. These methods enable the optimization of sheet stamping used for numerous elements of a body-in-white. It results in the reduction of a vehicle’s weight, the reduction of a number of scrap, parts, reinforcements and finally it reduces the manufacturing costs.
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