Deep Drawing Tests Research Articles

Deep Drawing of ZK60 Wrought Magnesium Alloys

Evolution of texture and microstructure during deep drawing of ZK60 wrought magnesium alloys were investigated using EBSD (electron backscatter diffraction). ZK60 (Mg-5.5Zn-0.6Zr) alloys were prepared through both direct chill casting (DC) and twin-roll strip casting (TRC). Deep drawing tests were carried out under various working temperature and drawing speeds. The diameters of the sheets and punch were 74 mm and 37 mm, and overall limit drawing ratio was 2. Texture and microstructure evolution was examined with various working condition. The DC samples had larger grains than TRC samples, and thus more twins were observed in the DC samples.

Effect of Blank Holder Force with Low Frequency Vibration Technique in Circular-Cup Deep-Drawing Using AZ31 Magnesium Alloy Sheet

In the deep-drawing process, the application of low-frequency vibration to the blank material has recently been focused on with the aim of improving the friction performance between the die and the blank material. A servo-controlled press machine is suitable for applying low-frequency vibration to the blank during the deep-drawing process, because the punch speed and blank holder force (BHF) are easily controlled as process parameters by using the servo motors. In this study, a BHF with low-frequency vibration was proposed as a technique for improving deep-drawability, which is mainly affected by the friction performance and the lubricant condition. We found that the friction performance between the blank surface and the blank holder was decreased in the case of a BHF with low-frequency vibration since the lubricating oil rapidly flowed into the clearance during the forming process. Furthermore, for a BHF with low-frequency vibration, the punch force and the deformation resistance were lower than those in a deep-drawing test without low-frequency vibration.

Forming and fracture limits of aluminium alloy

Forming and fracture limits of an AA 3104-H19 aluminium alloy sheet were studied by hydraulic bulging and Marciniak type deep drawing and tensile tests. The alloy appeared to be highly anisotropic, exhibiting distinctly different fracture patterns in the rolling and transverse directions. The preferred fracture direction was transverse to the rolling direction. In the tensile test, samples loaded in the rolling direction failed transverse to the rolling direction, but in the transverse direction, the fracture was inclined at ∼55° to the tensile axis. In some cases, two such competing fractures in the characteristic directions could be observed. Scanning electron microscopy studies revealed a typical ductile fracture pattern. The fracture occurred by shearing in the through thickness direction, and typical alternating shear lips in a direction inclined at ∼45° to the through thickness direction could be observed. Forming limit diagrams for both rolling and transverse directions were determined from the experiments. The measured limit strains in uniaxial tension were predicted well by the modified Rice–Tracey theory, but in equibiaxial tension, the theory overestimated the fracture limit strains.

Finite Element Analysis and Deep Drawing of Cylindrical Cups with 5A90 Al-Li Alloy Sheets

The cylindrical cup drawing of 5A90 Aluminum-Lithium alloy sheets at various forming conditions was studied by both the experimental approach and the finite element analysis. The uniaxial tensile tests and forming limit tests of 5A90 Al-Li alloy sheets at various temperatures were first carried out. The tests results were then employed in the finite element simulations to investigate the effects of process parameters, such as forming temperature, holder force, and die corner radius, on the formability of cylindrical cup drawing with 5A90 sheets. In order to validate the finite element analysis, the corresponding deep drawing tests were also carried out. It is shown that the simulation results are in qualitative agreement with the experimental observations. The optimal forming temperature, diameter of blank, holder force, punch radius and die corner radius were then determined for the cylindrical cup drawing of 5A90 sheets, and the limit drawing ratio (LDR) reached 2.4 in the optimal parameter conditions.

Ti–3Al–2.5V薄板の角筒深絞り成形シミュレーション

FEM analysis utilizing Barlat–Lian'89 anisotropy model and square shell deep drawing test at room temperature were carried out in order to improve the formability of Ti–3Al–2.5V sheet. As for the flange wrinkle, FEM analysis coincide with the experimental result more in case of 1.5% R-value than that of 5% R-value. The bigger the ΔCL , the greater the flange wrinkle. On the contrary the bigger the Rave, the smaller the flange wrinkle. Moreover, flange wrinkle decreases abruptly when Rave becomes equal or exceeds 2.0 in case that forming height becomes maximum value of 30 mm. And the flange breakage, occurs at the straight region of C-direction, proved to be caused by the shear stress.

連続マイクロドライ円筒深絞り加工における<br>SUS304ステンレス鋼箔材の摩耗•凝着挙動

Scaled progressive dry deep-drawing test is conducted up to 300 times on the micro- and milli-scales, in which cups of 0.97 and 5.82mm diameters are produced with stainless steel foils of 0.05 and 0.3mm thicknesses, respectively. The experimental results show that the transition of maximum punch force in the repetition test has a different tendency for each scale and corresponds to the transition in the surface state of the tools and drawn cups. Although the strong adhesive wear is observed on the milliscale, there is little change in the surface state of tools and drawn cups on microscale. To investigate the wear behavior of work material on each scale, finite element analysis considering surface asperities is conducted. The distribution of wear volume at the die corner radius is evaluated with a semiempirical function of normal pressure and relative velocity between the blank and the die. The results show the low wear volume in the microscale process, due to the short sliding distance during the process. The progressive wear phenomena and the advantage of tool life in microforming are demonstrated.

Stress Oriented Delayed Cracking Induced by Dynamic Martensitic Transformation in Meta‐Stable Austenitic Stainless Steels

AbstractDelayed cracking in meta‐stable austenitic stainless steels AISI 304 and AISI 301 has been investigated by deep drawing test in this study. Specimens from both steels were deformed at different drawing ratios, forming temperatures and hydrogen pre‐charged conditions. The strain, martensitic fraction and residual stress distributions were characterised on the deep drawn specimens. Their influences on delayed cracking behaviours were quantitatively studied. We found that the incubation time to fracture and the fracture length depend chiefly on the amount of strain induced phase transformation and transformation induced residual stresses when the materials contain ∼1ppm hydrogen. When the materials were electrochemically charged with hydrogen up to the amount of 20ppm, the incubation time to fracture declined with increasing hydrogen contents following a power law relation. Besides, the fracture mode turned from a ductile nature to trans‐granular and later on to inter‐granular fracture feature with increasing hydrogen contents.

High Speed Twin-Roll Casting of Al-Mg Alloys

The disadvantages of the conventional twin-roll caster for aluminum alloy are low casting speeds and limited choices of alloys that are castable by this processing. It is known that strip casting of aluminum alloy 5182 is very difficult because of their wider freezing zones. The vertical-type high-speed twin-roll caster used in the present study was devised to overcome these disadvantages. Features of the high speed twin roll casters are as below. Mild steel rolls were used in order to increase the casting speed and to be made at a lower equipment cost. Roll coating is produced in casting of Al-Mg alloy. Therefore lubricant, that resists heat transfer, was not used in the present study. Heat transfer between melt and the roll was improved by hydrostatic pressure of the melt. Low superheat casting was carried out in order to improve microstructure of the strip. In the present study, effectiveness of a high-speed twin roll caster for recycling aluminum alloy was investigated. The effects of the high-speed twin roll caster on alleviating the deterioration of mechanical properties by impurities were investigated. Properties of the cast strip were investigated by metalography, a tension test, and a deep drawing test.

Mechanical and anisotropic behaviors of 7075 aluminum alloy sheets

Formability of 7075 aluminum alloy sheets was studied after annealing of 71% cold worked (CW) samples at different temperatures (270–450 °C). Uniaxial tensile test, deep drawing and Erichsen test were carried out at room temperature to evaluate formability parameters. Average plastic strain ratio, planar anisotropy, and work hardening exponent of samples were calculated from the tensile test data. The tensile properties and formability parameters were correlated with the limit drawing ratio (LDR) and Erichsen test. It was found that the sheets annealed at 400 °C possess good ductility, high average n-value and the normal anisotropy r-value so that, the formability of 7075 aluminum alloy can be improved by increasing annealing temperatures to the 350–400 °C.

Erratum to: On the reduction of gloss property of organic coated sheet metals after forming

Organic coated sheet metals (OCSM) are widely used in many industrial applications such as automobile or electrical appliances because of their corrosion resistance and satisfaction of ecological requirements. Nevertheless, original functions of the very thin coating layer in OCSM products may be altered after being formed which consequently leads to a reduction of the product’s quality. This paper deals with the reduction of gloss property of OCSM products. A forming limit diagram (FLD), a forming limit diagram of the coating layer (FLDC) of OCSM and a forming diagram for the prediction of gloss reduction are determined by using Nakajima tests. The Nakajima tests are performed with predefined strain states of the specimen. The experimental results show the dependency of the FLDC curve and the gloss reduction on both the equivalent strain and the strain ratio. Deep-drawing tests prove the applicability of the determined forming diagrams to predict coating fracture and gloss properties of OCSM after sheet metal forming and, thus, their potential as a tool for the process design for OCSM products.

Effects of Surface Strength and Temperature on Warm Forming of MG-AL-SUS Clad Sheet

Clad metal sheets are composed of one or more different materials joined by resistance seam welding, roll-bonding process, etc. Good formability is an essential property in order to deform a clad metal sheet to a part or component. Temperature is one of the major factors affected the interface strength and formability on warm forming of multilayered sheet metal. In this study, the mechanical properties and formability of a Mg-Al-SUS clad sheet are investigated. The clad sheet was deformed at elevated temperatures because of its poor formability at room temperature. Tensile tests were performed at various temperatures above 250°C and at various strain rates. The limit drawing ratio (LDR) was obtained using a deep drawing test to measure the formability of the clad sheet. Interface strength and fracture pattern were changed mainly by temperature. Uniaxial tensile strength represents entirely different type below and above 200°C at also different strain rate. Mg alloy sheet was fractured earlier more than SUS and Al alloy sheet below 250°C testing temperature. On the contrary, Mg alloy sheet was elongated much more than other metals above 250°C.

베릴륨동 극박판의 드로잉 성형성과 품질특성 연구

The present study is focused on the deep drawability and product qualities of ultra thin beryllium copper sheet metal. The goal of this research is to investigate the limit drawing ratio in deep drawing of ultra thin beryllium copper metal. For the experiment, beryllium copper(C1720, <TEX>$50{\mu}m$</TEX> in thickness) is used. Tensile test are also carried out to find out the material properties. Deep drawing experiments are carried out in Universal Testing Machine(UTM) to obtain limit drawing ratio. Deep drawing tests are carried out for various specimen sizes. Teflon film is used as a lubricant and constant blank holding force is imposed. Sheet thickness and surface hardness are measured along radial direction after deep drawing. Thickness is measured using optical microscope. For beryllium copper(C1720), the maximum LDR of 2.4 is obtained when the die shoulder radius is 20 or 30 times of sheet thickness.

A Numerical Simulation Study of Deep Drawing Testing and Experimental Results of Steel Sheets, Using a Comercial Software

Present work examines the accuracy of numerical simulation results of deep drawing testing of steel sheets through employing the commercial finite element software AutoForm to reproduce the punch force versus displacement. Numerical simulation is nowadays a modern engineering practice for sheet metal product and tooling design developments, using the finite element method. Historically, sheet metal formability has been assessed by tensile testing and biaxial stretching such as the Erichsen simple test. Lately, the concept of experimental Forming Limit Curve for strains, FLC, and the numerical simulations were developed to evaluate sheet metal formability and its forming operations by predicting the onset of local necking and fracture. In the present work, five types of steel sheets and one aluminium alloy AA6022 sheet were employed in the deep drawing tests with the same flat punch and die to obtain the experimental results of force versus punch displacement which were presented by De La Cour. The steel sheets with the same blank diameter utilized in the simulation and experimental testing were DQSK, BH33, HSLA50, TRIP600 and DP600 which different thickness varied from 0.783 mm to 1.601 mm. The experimental curve of punch force versus displacement were compared with the numerical simulation results by AutoForm, using 3D shell elements, hardening law defined by the effective stress \( {\overline {\upsigma }} { = }\upsigma_{\text{o}}\left( {1 + \upbeta }\overline {\upvarepsilon } \right)^{\text{n}}\) and friction coefficient of 0.10 between the blank hold and blank and 0.075 between blank and die. The average experimental hardening law curve for tensile tests at 0°, 45° and 90° and the Hill’s 1948 yield criteria, assuming isotropic plasticity, were used to numerically simulate the plasticity behavior during the deep drawing of steel and aluminium sheets. The simulated curves are situated above the experimental points of punch load for all materials. The calculated error varied from 2% to 8.5% for points near the maximum load. The principal characteristics of reliable software for numerical simulation of deep drawing process are also discussed, considering the actual tendency to use software in the design of dies and sheet metal manufacturing process analysis.

On the reduction of the gloss property of organic coated sheet metal after forming

Organic coated sheet metals (OCSM) are widely used in many industrial applications such as the automobile industry or in electrical appliances because of their high corrosion resistance and satisfaction of ecological requirements. However, original functions of the very thin coating layer in OCSM products may change during forming, which leads to a reduction of the product’s quality. This paper deals with the reduction of the gloss property of OCSM products. To this end, first a forming limit diagram (FLD) and a fracture limit diagram of the coating layer (FLDC) of OCSM are established by using Nakajima tests. Subsequently, the Nakajima tests are performed at a predefined strain in order to evaluate the change of the gloss property depending on the strain states. The loss of gloss as a function of plastic strain is used as a reference. For the verification of this reference, deep-drawing tests are carried out and the change of the gloss property on the surface is analyzed. The obtained results are in good agreement with the reference, so it can be applied for process design to predict the gloss reduction of OCSM products.

Deep drawing simulation of a metastable austenitic stainless steel using a two-phase model

This paper deals with the numerical simulation of the deep drawing of a metastable austenitic stainless steel of AISI 304 type. A two-phase model of elastoviscoplastic type has been developed by Gallée et al. (2007) to take into account the martensitic transformation induced by plastic deformation during cold forming that can exhibit this stainless steel. This two-phase model is used to describe the behavior of the steel during the numerical simulation of the deep drawing of a cylinder cup using a commercial finite element code. The numerical results of the simulations are compared with experimental results of the same deep drawing test in order to validate the model.

A novel approach for anisotropic hardening modeling. Part II: Anisotropic hardening in proportional and non-proportional loadings, application to initially isotropic material

The modeling of anisotropic hardening, in particular for non-proportional loading paths, is a challenging task for advanced macroscopic models. The complex distortion of the yield locus is related to the activation and cross-hardening of different slip systems, depending on crystallographic orientations. These physical mechanisms can be taken into account in polycrystalline models but the computation times are enormous. The novel approach detailed in Part I ( Rousselier et al., 2009) consists in: (i) drastically reducing the number of crystallographic orientations to save the computation cost, (ii) applying a parameter calibration procedure to obtain a good agreement with the experimental database. This methodology is first applied here to the anisotropic hardening in the proportional loadings of the strongly anisotropic aluminum alloy of Part I. Very good modeling is achieved with only eight crystallographic orientations. Different levels of additional hardening in biaxial proportional loading as compared to uniaxial loading can be modeled with the same polycrystalline model. For this, only the parameter calibration has to be performed with different databases. The same methodology has also been applied for the modeling of isotropic behavior. The best compromise between model accuracy and numerical cost is obtained with fourteen orientations. The deviations from isotropy are acceptable in all loading directions. Different levels of hardening in orthogonal loading: simple shear followed by simple tension, are achieved without any modification of the model equations. Only the parameter calibration has to be performed with different hardening levels in the database. FE calculations of a deep drawing test have been performed. The CPU time of the polycrystalline model is only five times larger than that with the simple von Mises model. The CPU time with texture evolution is further increased by a factor of two. The effects of texture evolution in rolling of the initially isotropic fcc material have been investigated. The resulting texture and hardening are qualitatively good.

Press Joining Rolling Process for Hybrid Systems

The press joining rolling process used for the production of metal/polymer/metal systems is introduced. In the first step three-layer sandwich sheet, 316L/polypropylene- polyethylene/316L (316L/PP-PE/316L) with and without local reinforcement, were processed by roll bonding at approx. 250°C of two steel sheets with a pre-rolled PP-PE - core sheet. Mechanical and forming behaviour of the parts had been investigated by tensile, bending and deep drawing tests. It could be shown that for moderate drawing depths deep drawing behaviour is close to the one of the mono-material.

Corrosion Behaviors of Two Types of Commercial Stainless Steel after Plastic Deformation

The influence of deformation temperature, strain rate and alloying elements such as chromium, nickel, copper, on corrosion resistance of a 304 stainless steel after plastic deformation was investigated. The techniques employed were tensile test at room and elevated temperature, deep drawing tests at various strain rates, X-ray diffraction test and potentiodynamic and cyclic polarization, metallography by optical and scanning electron microscopy. Results showed that chromium, nickel and copper had a significant effect on corrosion resistance of steel after plastic deformation. It was observed that corrosion resistance after plastic deformation was a function of deformation temperature and alloying elements.

Failure prediction of magnesium alloy sheets deforming at warm temperatures using the Zener-Holloman parameter

In the present study, a new method of predicting fracture in magnesium alloy sheet deforming under warm-working conditions has been developed. The effects of temperature and strain rate have been incorporated into the ductile fracture criteria by formulating the damage growth resistance as a function of strain rate and temperature based on the finding of correlation between the fracture strain (or fracture work) obtained from a series of uniaxial tensile tests performed over wide ranges of temperature and strain rate and the Zener-Holloman parameter. Comparison between the maximum drawing depths in cup deep-drawing tests predicted by the finite element code coupled with the fracture criteria and the experimental data indicates that the newly developed fracture criteria may be quite useful in predicting the fracture behavior of magnesium sheets during non-isothermal forming. The proposed failure models are simple and readily applicable to other metallic alloys at elevated temperatures.

An analysis of the formability of aluminum/copper clad metals with different thicknesses by the finite element method and experiment

In this research, the possibility of applying forming limit diagrams to the formability and fracture prediction of clad metal sheets is examined. The forming limits of clad metal sheets with different thickness combinations (e.g., A1050 1.0, 1.5, 2.0 mm/C1100 1.0 mm) are investigated via forming limits test (punch stretching tests). The true stress–strain curves of Al/Cu clad metal sheets are obtained through tensile tests. Using the experimental forming limit diagrams and the stress–strain curves, the fracture prediction of clad metal sheets are simulated by finite element analysis. Moreover, deep drawing tests are carried out to compare the experimental with the numerical results. These results can verify the accuracy of finite element model. Finally, significant differences in formability are found, and comparisons of the fracture prediction of clad metals with different initial thickness ratios are analyzed both numerically and experimentally.