Mechanical Properties Of Sheet Metal Research Articles

The Effect of Tool Path Strategy on Twist Behavior In Single Point Incremental Sheet Metal Forming

In Incremental sheet metal forming process, one important step is to produce tool path, an accurate tool path is one of the main challenge of incremental sheet metal forming process. Various factors should be considered prior to generation of the tool path i.e. mechanical properties of sheet metal, the holding mechanism, tool speed, feed rate and tool size. In this work investigation studies have been carried out to find the different tool path strategies to control the twist effect in the final product manufactured by single point incremental sheet metal forming (SPIF), an adaptive tool path strategy was proposed and examined for several Aluminum conical models. The comparison of the proposed tool path with the conventional iso planar and helical tool paths shows that there is no effect of twisting in the final model when using adaptive tool path, while the twisting effect are clearly observed and measured in the final product when using both iso planar and helical tool path When forming 80 and 110mm depth conical cup. The time of forming has been measured and its observed that in adaptive tool path the time of forming is less than 8.7 %from the helical tool path when forming conical cup with 50mm depth and less than of 8.91% when forming conical cup with 110mm depth

Asymmetric (Hot, Warm, Cold, Cryo) Rolling of Light Alloys: A Review

Asymmetric sheet rolling is a process used when there are differences in any technological parameters in the horizontal plane across the width of the deformation zone or in the vertical plane between the top and bottom surfaces of the deformation zone. Asymmetry can either have random causes, or it can be created purposefully to reduce rolling force, improve sheet flatness, minimize the ski effect, obtain thinner sheets and for grain refinement and improvement of texture and mechanical properties of sheet metals and alloys. The purpose of this review is to analyze and summarize the most relevant information regarding the asymmetric (hot, warm, cold, cryo) rolling processes in terms of the effect of purposefully created asymmetry on grain size and mechanical properties of pure Mg, Al, Ti and their alloys. The classification and fundamentals of mechanics of the asymmetric rolling process are presented. Based on the analysis of publications related to asymmetric rolling, it was found that a superior balance of strength and ductility in pure Mg, Al, Ti and their alloys could be achieved due to this processing. It is shown that asymmetric rolling in comparison with conventional severe plastic deformation methods have an undeniable advantage in terms of the possibility of the production of large-scale sheets.

The effect of thermal spraying on the forming performance of incremental sheet forming

Abstrac In order to reduce the manufacturing cycle and improve the forming performance of the incremental sheet forming (ISF) process, a hybrid manufacturing process that combines thermal spraying and incremental forming process was firstly proposed. The effects of different thermal spraying parameters on the forming properties and mechanical properties of sheet metal were investigated. Firstly, Fe316L coating was prepared on AA2024-T3 plate by using atmospheric plasma thermal spraying, and then the plate is formed into the target shape with variable angles. In addition, tensile tests were carried out on the plates pretreated by thermal spraying with different parameters. The results showed that the yield strength of the plate decreased up to 70% and the elongation increased by 65% under the appropriate thermal spraying power. In the process of ISF, the axial forming force of sheet metal after thermal spraying decreased obviously and the forming limit increased obviously. In addition, influences of different processing steps (sand blasting and heating) on the forming performance of sheet metal were investigated. It is found that the heating effect in the thermal spraying process has the most obvious effect on the improvement of forming performance, while the sand blasting process has adverse effect. Finally, in order to optimize the thermal spraying area, the influence of thermal spraying at different areas on the forming performance of sheet metal was investigated.

Comparison of Artificial Intelligence Methods for Prediction of Mechanical Properties

This paper compares artificial intelligence (AI) methods to predict mechanical properties of sheet metal in stamping processes. The deviation of the mechanical properties of each blank leads to unpredicted failures in stamping processes, such as fracture and spring back. The research team of this paper has been building a real time control system for stamping process in a smart factory. In order to facilitate that, it is necessary to predict the mechanical properties of each blank with non-destructive testing. The regression models based on the linear algebraic scheme have traditionally brought reliable results in terms of matching the measured non-destructive testing values to the mechanical properties. With a parallel to algebraic regression models, in recent studies on various domains, AI models have been adopted to improve the accuracy of the end-results and effectiveness of the models. This paper discusses the applicability of AI models for predicting the mechanical properties based on the eddy-current non-destructive testing method. For the study, 6 input features are collected through the eddy-current non-destructive testing to map eddy-current input data to mechanical properties of the blank. Yield stress and uniform elongation were predicted by using five AI methods, i.e., regularized linear regression, support vector regularized linear regression, support vector regression, multi-layer neural network, random forest regression, and gradient boosting regression were compared. The model performance, validated with 20% of test data that are intact during the training phase, is the main discussion point of this paper. Future works to improve the predictive accuracy of AI models is also discussed.

Influence of rolling and annealing modes on properties of semi-finished sheet products made of aluminum deformable alloy 1580

The study covers the manufacturability and properties of sheet metal obtained from a large-sized ingot of Alloy 1580 with the low scandium content within its grade range. The ingot processability in hot and cold rolling was evaluated, and the influence of the degree of deformation and annealing conditions on the properties of cold-rolled semi-finished products made of the alloy under study was investigated. A large-sized commercially produced ingot with a cross section of 500×2100 mm of Alloy 1580 with a scandium content of 0.067 wt.% was selected as an object of research. The research methodology included several stages of rolling and heat treatment of semi-finished sheet products at various stages of the developed mode for metal deformation and mechanical testing of samples from them on the LFM 400 kN universal machine. For research, a 60×500×900 mm template was cut from the ingot to make 50×180×300 mm billets for rolling. Billets were subjected to homogenization annealing by the two-stage mode developed previously for this alloy. As a result of hot rolling of annealed billets at 450 °C and a total relative compression e Σ = 84÷90 %, 5–8 mm thick semi-finished sheet products were obtained. Further, after their annealing at t = 320 °C for 6 hours, light-gauge semi-finished sheet products with a thickness of 2 to 6 mm were manufactured by cold rolling. They were subjected to mechanical analysis in the deformed and annealed states. The analysis of their mechanical properties in the deformed and annealed states was performed, which showed that the accumulation of the total degree of deformation during cold rolling up to 38 % provides the 1580 alloy with an increase in strength properties to R p = 380 MPa, and after that the growth rate slows down and at e Σ = 60 % R p = = 400 MPa. The effect of annealing at temperatures between 250 °C and 350 °C on the mechanical properties of sheet metal. It was found that it leads to a decrease in strength properties and an increase in ductility, and the maximum yield strengths correspond to annealing temperatures of 250–275 °C at a sufficiently high plasticity. As a result of studies, it was found that the strength properties of sheet metal from Alloy 1580 with a low scandium content exceed the strength properties of semi-finished products of Alloy AW-5083 (USA) having a similar chemical composition, but without the addition of scandium, by 10–15 %, and the excess in plastic properties is 40–60 %.

Excellent Combination of Tensile ductility and strength due to nanotwinning and a biamodal structure in cryorolled austenitic stainless steel

Austenitic stainless steels are prominent materials for their superior corrosion resistance and a combination of strength and ductility. However, the relatively low yield strength limits its application in high strength structural applications. Cryorolling is one of the promising methods of enhancing the mechanical properties of sheet metals. In the present work, Cryorolling of UNS S31000 stainless steel resulted in five-fold enhancement in yield strength with a significant loss in ductility. However, flash annealing at 800 °C for 120 s could restore its ductility up to 50% of its original ductility. The enhancement in strength is attributed to the formation of deformation nano-twins during flash annealing along with a bimodal grain structure.

Influence of Alternating Short-Cycle Bending on the Mechanical Properties of Copper, α-Titanium and the Mild Steel DC01

The influence of alternating bending loads as they occur during roller levelling on the mechanical properties of sheet metals is not yet fully understood. A detailed knowledge of the influence of the commonly used levelling process on the resulting properties of sheet material is needed in particular for the design of subsequent processes with narrow process windows. To investigate the mechanical property changes during loading conditions similar to roller levelling, sheet samples of mild steel DC01, α-titanium and pure copper (CU-DHP) were subjected to alternating bending loads with different amplitudes for up to 9.5 bending cycles. An isotropic hardening behavior according to a Voce description could be shown for the DC01 deep drawing steel with a strong dependence on the load amplitude applied per cycle. A strengthening behavior that depends on the loading amplitude could be observed for α-titanium as well. In contrast, pure copper featured minor changes with a tendency to soften. For all three materials, changes in springback were present after one bending cycle.

Effect of scheme of rolling and post-deformation cooling on mechanical properties of rolled sheet made of V−Nb−Al-alloyed steel

Problem statement. Structural steel products are the bulk of the production of modern metallurgy. It is advisable to increase the mechanical properties of rolled products in the framework of technologies involving the use of rolling heating, which saves energy and reduces the production cost. Purpose. The choice of a rational scheme of rolling and post-deformation cooling of rolled steel made of structural steel. Material and Methods. The study material is 20 mm thick sheet steel made of S355J2 steel (EN 10025) micro-alloyed with V−Nb−Al complex. Methodology − tests for mechanical properties according to the requirements of EN 10025. Results. The mechanical properties of sheet metal are compared after performing standard hot rolling, normalizing rolling, controlled rolling, and also after controlled rolling with subsequent accelerated cooling in various modes. Conclusions. It is shown that by using controlled rolling with accelerated cooling to 460…530 °C, it is possible to significantly (by one third, up to category 500Q) increase the strength of steel with an increase in its cold resistance and at the same time maintaining plasticity at an acceptable level. Such an increase in the complex of properties is achieved without the use of heat treatment with special heating, which is an economically advantageous direction.

Study of the mechanical properties of sheet metals drawn through drawbeads

The use of modern materials leads to a need for detailed knowledge of the material flow. Drawbeads are one common way to control serial forming processes. Although they are already well investigated, the effect on the resulting mechanical properties after a drawbead passage is not analysed in detail yet. This work is showing the influence of a drawbead geometry used in deep drawing on typical mechanical properties. Therefore, different sheet metal materials are preloaded in a modified strip drawing test with commonly used drawbeads. In testing, three different levels of pressure between 2.5 MPa and 7.5 MPa and of drawing speed between 10 mm/s and 50 mm/s are combined to nine variations and are examined. Afterwards, specimens are cut out by a laser cutting machine of the drawn strips. Those specimens are then tested with the use of an optical measurement system. Results are discussed in relation to blankholder pressure, drawing velocity and drawbead geometry to work out the main effects. Overall it can be stated, that variations of blank holder pressure and drawbead height lead to significant changes for the material properties. A variation of the drawing velocity in the observed range does not show significant effects.

Finite Element Analysis of Incremental Sheet Forming for Metal Sheet

Incremental sheet metal forming, is a non-conventional machining process which offers higher formability, flexibility and low cost of production than the traditional conventional forming process. Punch or tool used in this forming process consecutively forces the sheet to deform locally and ultimately gives the target profile. Various machining parameters, such as type of tool, tool path, tool size, feed rate and mechanical properties of sheet metal, like strength co-efficient, strain hardening index and ultimate tensile strength, effects the forming process and the formability of final product. In this research paper, Single Point Incremental Forming was simulated using Dassault system’s Abaqus 6.12-1 and results are obtained. Results of sheet profile and there change in thickness is investigated. For this paper, we simulated the process in abaqus. The tool diameter and rotational speed is find out for the production of parts through incremental forming. The simulation is done for two type of material with different mechanical properties. Various research papers were used to understand the process of incremental forming and its simulation.

Investigation of mechanical properties of cold-rolled, annealed and welded semi-finished products from the test alloys of Al-Mg system, economically alloyed with scandium

The results of experimental investigation of mechanical properties of sheet metal from an experimental aluminum alloys Al–Mg system alloyed with scandium have been represented. It was established that the deformed and annealed semi-finished products of these alloys have higher strength properties. Testing of welded samples made from these semi-finished products showed high corrosion resistance and strength of welded joints.

Variation of tensile and bending rigidities of a duplex embossed steel sheet by small uniaxial tensile deformation

Materials which have periodic macroscopic structure have some potential for becoming an advanced method to enhance the mechanical properties of sheet metal which will be applied to automotive parts and architecture. This structure, achieved here by embossing sheet metal, could improve mechanical features, especially bending rigidity. In addition to the microscopic aggregate structure, periodic configurations given by embossing bring about new quasi-uniform “apparent” macroscopic properties. When an embossed sheet is subjected to plastic deformation, the new shape would include these apparent mechanical properties. In this study, uniaxial tensile tests and bending tests of duplex embossed sheets, which have periodic convexities and concavities, were conducted experimentally and analytically respectively. And tensile rigidity and bending rigidity were evaluated by changing the embossing height and direction. The variation of these rigidities with different preliminary small uniaxial tensile deformations (pre-strains) was also investigated. The results confirmed that the tensile rigidity of embossed sheets with larger embossing height was lower than that of sheets with smaller embossing height. However, when preliminary tensile deformation was added, the tensile and bending rigidity increased. On the other hand, the bending rigidity of embossed sheets with larger embossing height was considerably higher than that of sheets with smaller embossing height. The degree of these tendencies varied depending on the embossing direction. Furthermore, from analytical results, the evaluation method which was used apparent geometry in this study, it is suitable to evaluate duplex embossed sheets due to it includes local rotating and bending deformation are accompanied with the plastic deformation. Also, it is considered that the apparent bending rigidity is a comprehensive value which can express more realistic macroscopic deflection behavior of embossed sheet.

Microstructure, Mechanical Properties and Welding of Low Carbon, Medium Manganese TWIP/TRIP Steel

Manganese twinning induced plasticity (TWIP) steels are attractive materials for the automotive industry thanks to their combination of strength and excellent toughness. This article deals with basic microstructural and mechanical properties of sheet metal of two heats of low-carbon medium-manganese steel with different aluminium levels. Microstructure observation was carried out using optical and scanning electron microscopy. Electron backscatter diffraction (EBSD) and X-ray diffraction were used for phase analysis. In an experiment that focused on the weldability of both materials, sheet metals were laser-welded using various laser power settings, with and without shielding gas. Various combinations of joints between materials of the two heats and sheet metal conditions were tested (work-hardened upon cold rolling + annealed). Mechanical properties of the weld joints were determined using miniature tensile testing and conventional hardness measurement. The strengths of miniature specimens of the weld metal were very close to the strength of the base material.

Effect on the mechanical properties of sheet metals after the use of drawbeads in deep drawing

The use of modern and more complex materials leads to a need for detailed knowledge and controlling of the material flow. Next to the blank holder force or the lubrication system, drawbeads are nowadays one common way to bring serial forming processes under control. Although drawbeads are already well investigated regarding their retention forces, the effect on the resulting mechanical properties after a drawbead passage is not analysed in detail yet. This work will show the influence of a common drawbead geometry used in forming processes on typical mechanical properties of sheet metal. Therefore, two different sheet metal materials are preloaded in a modified strip drawing test with industrial used drawbead geometry. In testing, three different pressure levels between 2.5 MPa and 7.5 MPa and three levels of drawing speed between 10 mm/s and 50 mm/s are combined to nine variations which will be examined. Afterwards, specimens are cut out by a laser cutting machine of the drawn strips. Those already preloaded and deformed specimens are then tested under standard conditions with the use of an optical measurement system. The results like tensile strength or elongation at fracture are compared to the initial state and each other and discussed with consideration of pressure and speed levels to work out the main effects. Those results are a contribution for the optimization of deep drawing simulations of parts including drawbeads or to evaluate the influence of drawbeads on forming processes to specify or even expand process limitations.

A new method for predicting advanced yield criteria input parameters from mechanical properties

Many advanced yield criteria have been developed in the last twenty years, but their use in forming simulations is still limited. In most simulations, the traditional Hill’48 model is still applied and this is understandable given that it is easy to use and does not require extensive test data. However, the Hill’48 criterion is too rigid to describe all stress states accurately, for this a more advanced model is needed. The drawback of such models is that they usually require data from an extensive range of laboratory tests.In the sheet metal forming industry, the tensile test is the standard procedure with which the mechanical properties of sheet metals are measured. It is therefore desirable that the multiple parameters required for advanced yield criteria are also able to be derived from the mechanical properties from the tensile test, as for Hill’48.In the work presented here, a correlation has been established between measured stress factor input parameters and the mechanical properties derived from the tensile test. Leading from this correlation, a new method is proposed to generate stress factors directly from simple mechanical properties. With this method it is possible to predict the biaxial, plane strain and shear points accurately using only tensile test data, notably tensile strength, uniform elongation and the plastic anisotropy r-value measured at 0°, 45° and 90° to the rolling direction.Initially aimed at low carbon steels, the proposed method is shown to be applicable to stainless steel and aluminium alloys as well. The accuracy of the predicted stress factors has been verified by comparing simulation results with measurements of strain distribution, punch force, displacement and temperature. The comparisons of three strain paths on Nakazima specimens taken from a forming steel and a dual phase steel show a very good agreement between the measured and simulation results. Additionally, cross die tests on eleven materials, ranging from forming steels to Advanced High Strength Steels, have been used to assess the model. The results demonstrate that the proposed method of generating parameters for advanced yield criteria from tensile mechanical properties is highly accurate and very easy to use.

Development of sheet metal forming dies with excellent mechanical properties using additive manufacturing and rapid tooling technologies

Cost and time are two major concerns that are needed to manufacture new sheet metal forming dies in the industry. A cost-effective approach for rapid production of sheet metal forming dies with excellent wear resistance and mechanical properties was developed using additive manufacturing and rapid tooling technologies. This paper deals with the effect of zirconia (ZrO2) addition on the mechanical properties of sheet metal forming dies. Sheet metal forming experiments confirmed that the sheet metal forming dies fabricated by epoxy resin filled with 30 wt% ZrO2 particles have the low corner wear. The sheet metal dies can be fabricated within 2 days to meet the requirements of reducing the development time in the research and development stage for a new product.

The concept of virtual material testing and its application to sheet metal forming simulations

A crystal plasticity based full-field microstructure simulation approach is used to virtually determine mechanical properties of sheet metals. Microstructural features like the specific grain morphology and the crystallographic texture are taken into account to predict the plastic anisotropy. A special focus is on the determination of the Lankford coefficients and on the yield surface under plane stress conditions. Compared to experimental procedures, virtual material testing allows to generate significantly more data points on the yield surface. This data is used to calibrate anisotropic elasto-plastic material models which are commonly used for sheet metal forming simulations. A numerical study is carried out to analyze the influence of the chosen points on the yield surface on the calibration procedure.

A novel approach to determine plastic hardening curves of AA7075 sheet utilizing hydraulic bulging test at elevated temperature

Precise estimation of various mechanical properties of sheet metal with strong non-linearities has always been a major problem in process simulation by Finite Element Method (FEM). The hydraulic bulge test as prescribed in ISO standard 16808 is well-known for its capability of obtaining flow stress at higher strain levels compared to uniaxial tensile test, but a more applicable method is also needed to calculate the flow stress properties of bulge test especially at elevated temperature. In this study, a set of explicit integral format formulas based on the classical plastic flow rules were deduced to calculate thickness distribution from the aspect of the mechanics analysis. Afterwards an iterative method combined with integration formulas was established to evaluate hardening curves for specimen. Finally, A group of hydraulic bulge tests were performed using sheet metal of AA7075 alloy at room and elevated temperatures with a constant pressure increasing rate, supplementary tensile tests were also carried out at corresponding conditions to compare with the stress–strain curves from the bulge tests. Result shows that the proposed method can evaluate the flow stress curves of the test specimen with reasonable accuracy and with higher strain range over the temperatures ranging from cold to elevated values.

On the Solid Bonding Phenomena in Linear Friction Welding and Accumulative Roll Bonding Processes: Numerical Simulation Insights

Solid Bonding based welding processes allow to obtain defect free joints with low residual stress and low distortion. However, the engineering and optimization of solid bonding processes is difficult and requires a large number of time and cost consuming test trials. In this way, proper numerical models are essential tools permitting effective process design. The aim of this research was the comparison of the material process conditions during two different manufacturing processes taking advantage of the same metallurgical phenomenon, namely solid bonding. Linear Friction Welding, used to weld non-axisymmetric components and Accumulative Roll Bonding, used to increase the mechanical properties of sheet metals, were considered. Numerical models were set up, validated and used to design the process by studying the complex material behavior during the solid bonding of different aluminum alloys. An implicit approach was used for the Linear Friction Welding and Accumulative Roll Bonding processes, leading to the understanding of the main process variables influence on the field variables distribution and the occurrence of actual bonding.

Improvement in corrosion resistance of 5083 aluminum alloy via friction stir processing

Friction stir processing is a solid state process used to modify microstructure and mechanical properties of sheet metals and as-cast materials. During this process, stirring action of the tool causes the material to intense plastic deformation that yields a dynamical recrystallization. In this study, corrosion sensitivity of a friction stir processed AA5083 aluminum alloy has been investigated using both normalized intergranular corrosion test (ASTM G67) and local electrochemical open circuit potential measurements. In addition, Vickers microhardness and microstructural analyses have been performed. It was found that the friction stir processed samples exhibited higher corrosion resistance compared with the base metal.