scholarly journals Simulation Process Deep Drawing of Tailor Welded Blanks DP600 and BH220 Materials in Tool With Elastic Blankholder

2018 ◽  
Vol 68 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Alexander Schrek ◽  
Pavol Švec ◽  
Alena Brusilová ◽  
Zuzana Gábrišová
Keyword(s):  
Material Flow ◽  
Fem Simulation ◽  
High Strength Steels ◽  
High Strength ◽  
Weld Interface ◽  
Simulation Process ◽  
Tailor Welded Blanks ◽  
Negative Effect ◽  
The Individual ◽  
Interface Movement

Abstract The high-strength steels and tailor welded blanks (TWB) are applied in construction of cars parts to reduction of cars weight [1, 2]. The application of these materials brings possible complicatons during the forming when it proves the considerable influence of stress-strain characteristics differences of of the individual parts of TWB what result in non-constant material flow and consequently a negative movement of the weld interface [3, 4]. One of the ways of elimination of this negative effect is to choose a suitable blankholder system with optimal distribution of blankholder forces by using elastic blankholder with adjustable distribution of blankholder forces. Within the bounds of study the experimental blankholder system with elastic blankholder with adjustable distribution of blankholder forces was used [5, 6]. Finite element methods (FEM) simulation has unsubstitutable role n the study of formability of TWB whereby it is possible to determine the values and points of application of the blankholder forces [7, 8]. The FEM simulations results carried out in simulative LS-Dyna software are presented in this article which is focused on achieving weld interface movement minimalization of tailor welded blanks from DP600 and BH220 materials by optimization of blankholder forces [9, 10].

Friction Characterisation for a Tumbling Self-Piercing Riveting Process

2021 ◽  
Vol 883 ◽  
pp. 27-34
Author(s):  
Simon Wituschek ◽  
Michael Lechner
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Vehicle Design ◽  
Numerical Investigations ◽  
Process Route ◽  
Friction Factors ◽  
Material Systems ◽  
Body Construction ◽  
Riveting Process ◽  
The Individual

Due to increasing demands regarding ecological and economic specifications in vehicle design, the effort required for production is continuously increasing. One trend is the increased use of multi-material systems, which are characterised by the use of different materials such as high-strength steels or aluminium alloys. In addition to the varying mechanical properties of the components, an increased number of variants accompanied by different geometries is leading to increasing challenges on body construction. For the assembly and connection of the individual components, conventional joining methods reach their limitations. Therefore, new joining methods are necessary, which feature properties of versatility and can adapt to process and disturbance variables. One way of achieving tailored joints is to use a tumbling self-piercing riveting process. For the design of the process route, numerical investigations are necessary for which a characterisation of the friction properties is necessary. This paper therefore investigates the contact and friction conditions that occur in a tumbling self-piercing riveting process. The individual contacts between the process components are identified and based on this, suitable processes for the characterisation of the friction factors - and coefficients are selected and performed.

Springback Analysis in Bilayer Material Bending

2017 ◽  
Author(s):  
Chetan P. Nikhare
Keyword(s):  
Fuel Consumption ◽  
Elastic Recovery ◽  
Dissimilar Materials ◽  
High Strength Steels ◽  
Thick Layer ◽  
High Strength ◽  
Geometric Error ◽  
Forming Process ◽  
Tailor Welded Blanks ◽  
Geometric Defect

Exponential increase in the use of auto vehicles, and thus the fuel consumption, which relates to the air pollution, vehicle industry are in a strict environmental regulation from government. Due to which the innovation related to light-weighting is not only an option anymore but became a mandatory necessity to decrease the fuel consumption. To achieve this target, industry has been looking in fabricating components from high strength to ultra-high strength steels. With the usage of these material the lightweight was achieved by reducing a gage thickness. However due to their high strength property often challenges occurred are higher machine tonnage requirement, sudden fracture, geometric defect, etc. The geometric defect comes from elastic recovery of a material, which is also known as a springback. Springback is commonly known as a manufacturing defect due to the geometric error in the part, which would not be able to fit in the assembly without secondary operation or compensation in the forming process. Due to these many challenges, other research route involved is composite material, where light materials can be used with high strength material to reduce the overall vehicle weight. This generally includes, tailor welded blanks, multi-layer material, mechanical joining of dissimilar material, etc. Due to the substantial use of dissimilar materials, these parts are also called as hybrid components. It was noted that the part weight decreases with the use of hybrid components without compromising the integrity and safety. In this paper, a springback analysis was performed considering bilayer metal. For this two dissimilar materials aluminum and composite was considered as bonded material. This material was then bent in a channel forming set-up. The bilayer springback was compared in different condition like aluminum layer on punch side and then on die side. These results were then compared with the baseline springback of only aluminum thin and thick layer. It was found that the layer, which sees the punch side, matters due to the differences in elastic properties for both material and thus it directly influences the springback.

Metal Formability Interactions in Laser Marking for Creating of Grid Patterns for Forming Strain Analysis of High Strength Steels

2017 ◽  
Vol 746 ◽  
pp. 92-98
Author(s):  
Sergey Guk ◽  
Markus Preiß ◽  
Rudolf Kawalla
Keyword(s):  
Electrochemical Etching ◽  
Strain Analysis ◽  
High Strength Steels ◽  
Reference Method ◽  
High Strength ◽  
Grid Pattern ◽  
Laser Marking ◽  
Negative Effect ◽  
Working Parameters ◽  
Multiphase Steels

A commercially available laser marking system based on diode-pumped Nd:YVO4 laser was used for creating grid patterns for forming strain analysis of three different multiphase steels. The aim was to determine and analyze the influence of laser working parameters on the formability of the investigated sheet materials by means of an in-depth characterization of this induced microstructural and geometric inhomogeneity. The electrochemical etching served as the reference method without the negative effect of generating inhomogeneity. The formability was evaluated using the cupping test according to Erichsen. While the quantification of geometric inhomogeneity was based on the determination of the notch factor, microhardness measurement was used for the evaluation of micro-structural inhomogeneity. The results showed that multiphase steels exhibit similar values of the mark depth under the same creating parameters by means of laser. Furthermore, only the induced geometric inhomogeneity had a marked influence on the material formability. Finally, a method for the prediction of the optimal values of the grid pattern mark depth was developed from the perspective of its good visual recognizability and associated with the microstructure based material sensitivity to stress concentrators.

Forming Limit Extension of High-Strength Steels in Bending Processes

2014 ◽  
Vol 611-612 ◽  
pp. 1110-1115 ◽  
Author(s):  
Mohamed El Budamusi ◽  
Andres Weinrich ◽  
Chrstioph Becker ◽  
Sami Chatti ◽  
A. Erman Tekkaya
Keyword(s):  
Hydrostatic Pressure ◽  
Metal Forming ◽  
Fem Simulation ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Limit ◽  
Forming Limits ◽  
Air Bending ◽  
Forming Technology ◽  
Bending Process

Bending is a commonly used forming technology in metal forming. The occurring springback and low forming limits of high-strength steels especially during air bending are the main disadvantages. In this paper, the conventional air bending process is applied with a hydrostatic pressure in the bending zone. This was done using an elastomer tool. The advantage of this method is that the flexibility of air bending is maintained by reducing the springback while the forming limits are extended. Furthermore, different geometries for the elastomer tool were investigated by means of a FEM simulation. The investigation leads to a reduction of the process forces by minimizing the springback and to an extension of the forming limits.

Experimental Investigation on Forming of Tailor Welded Blanks

2017 ◽  
Vol 885 ◽  
pp. 147-152
Author(s):  
Gábor Béres ◽  
József Danyi
Keyword(s):  
Automotive Industry ◽  
Weight Reduction ◽  
Laser Beam Welding ◽  
High Strength Steels ◽  
High Strength ◽  
Drawing Ratio ◽  
Steel Component ◽  
Tailor Welded Blanks ◽  
Passenger Safety ◽  
Basic Parameters

One of the main aims of automotive developers is vehicle weight reduction. There are many well known ways related to weight reduction, for example using thinner and higher strength sheet materials, or using of formed tubes as load-bearing elements in car body structures. In the field of modern automotive industry we must not forget that the heavy loaded, and in passenger-safety aspect relevant elements frequently consist of tailor welded blanks (TWBs). The components could have different strength or thickness or coatings too. Therefore, certain segments of the welded elements could behave differently during forming. Generally the higher strength coupled with less formability, but in the case of welded blanks, the interaction of each parts are unknown in many aspects.This paper presents the results of the experimental work, carried out to evaluate the drawability of tailor welded blanks. The welded blanks were prepared by laser beam welding technology. The blanks consisted of a well drawing component, marked DC04, and a high strength steel component. The applied high strength steels are DP600, DP800 and DP1000 types. Our current object was to determine some basic parameters of deep-drawability as a typical sheet metal forming operation. It can be stated that as the strength ratio (SR) is increasing between the segments, the limiting drawing ratio is decreasing.

scholarly journals Correlation Modeling Between Peening-Induced Hardness, Residual Stress and Roughness in Case-Hardened High Strength Steels

2021 ◽  
Author(s):  
Hsin Shen HO ◽  
Cheng LV ◽  
Yonghui HE ◽  
Erliang ZHANG
Keyword(s):  
Residual Stress ◽  
Compressive Residual Stress ◽  
Linear Trend ◽  
Roughness Parameter ◽  
High Strength Steels ◽  
High Strength ◽  
Initial Material ◽  
Material Hardness ◽  
Negative Effect ◽  
The Relationship

The present paper is focused on the investigation of the correlation modeling of hardness and compressive residual stress on the surface and subsurface regions of case-hardened 18CrNiMo7-6 steels subjected to shot peening. The results exhibit that the relationship between hardness and compressive residual stress can reasonably well be approximated by an inverse linear model. The analysis suggests that the slope and y-intercept of the inverse linear trend line can be related to the compressive residual stress level and the initial material hardness, respectively. It is further revealed that the negative effect brought by the peening-induced roughness on the measurement of experimental data computed on the surface can be compensated by performing the normalization using the roughness parameter called the maximum valley height (Sv).

scholarly journals Some Formability Aspects of High Strength Steel and of Consisting Tailor Welded Blanks

2021 ◽  
Vol 4 (1) ◽  
pp. 18-23
Author(s):  
Gábor J. Béres ◽  
Ferenc Végvári ◽  
József Danyi
Keyword(s):  
Weld Line ◽  
High Strength Steels ◽  
High Strength ◽  
Vehicle Body ◽  
Pollutant Emission ◽  
Spring Back ◽  
Direct Function ◽  
Deep Drawability ◽  
Tailor Welded Blanks ◽  
Body Construction

Abstract In recent years, the demand for a reduction in pollutant emission has become extremely important in the vehicle industry. It can be achieved through fuel consumption reduction, which is a direct function of the vehicle’s weight. nowadays weight is widely controlled by the use of advanced- and ultra-high strength steels (AHSS and UHSS) in vehicle body construction. With the application of such steel sheets as chassis elements, crashworthiness can be maintained next to reduced sheet thicknesses, too. In this paper, the deep-drawability and springback after V-die bending is monitored for three types of AHSS grades, namely DP600, DP800 and DP1000 materials. The investigations are extended to tailor welded blanks (TWBs), made by the aforementioned steels coupled with a cold rolled steel sheet (DC04). Our results show that deep-drawability reduces with both the increase in strength and the increase in strength difference between the components in the TWBs. Furthermore, the higher strength is shown to cause higher spring-back. The TWBs have unique spring-back behavior around the weld line.

Optimization of Metallographic Sample Preparation for AFM/SKPFM Based Phase Distinction of Complex and Dual Phase High Strength Steels

2021 ◽  
Vol 58 (6) ◽  
pp. 308-331
Author(s):  
I. Traxler ◽  
G. Schimo-Aichhorn ◽  
A. Muhr ◽  
C. Commenda ◽  
A. Jerrar ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Hydrogen Permeability ◽  
High Strength Steels ◽  
High Strength ◽  
Dual Phase ◽  
Kelvin Probe ◽  
Preparation Methods ◽  
Force Microscopy ◽  
Steel Grades ◽  
The Individual

Abstract For the comprehensive investigation of advanced high strength steel grades, like complex and dual phase steels, Atomic Force Microscopy (AFM) and Scanning Kelvin Probe Force Microscopy (SKPFM) have proven to be useful tools, especially for analysis of hydrogen permeability of the individual steel phases. However, for these studies a preparation route, exposing the microstructure of the steel, is necessary. Various sample preparation methods were examined, focusing on electropolishing and sputtering, and the selected route was optimized to guarantee reproducibility and stability of the prepared surface. Electropolishing was shown to be highly efficient to selectively reveal the individual steel phases without introducing strong topographical features disturbing the AFM measurements. A subsequent sputtering step was introduced to improve the stability and preservability of the surface up to several months. Finally, distinction of the steel phases via AFM/SKPFM, was complemented and compared with results from EBSD and XRD.

Effects of Weld Line in Deep Drawing of Tailor Welded Blanks of High Strength Steels

2014 ◽  
Vol 611-612 ◽  
pp. 955-962 ◽  
Author(s):  
Thomas Mennecart ◽  
Alper Güner ◽  
Nooman Ben Khalifa ◽  
A. Erman Tekkaya
Keyword(s):  
Deep Drawing ◽  
Applied Load ◽  
Lightweight Design ◽  
Weld Line ◽  
Base Material ◽  
High Strength Steels ◽  
High Strength ◽  
Fe Model ◽  
Tailor Welded Blanks ◽  
Base Materials

Due to the increase of lightweight design in car bodies, there is a raise in use of tailored welded blanks (TWB). With these blanks it is possible to strengthen the car body where it is necessary. This can lead to less weight. In the case of tailored welded blanks, there is a weld line, which influences the deep drawing behavior significantly during forming. In the presented results two different high strength steels (HCT980X and HCT600X) are welded together. One forming operation is performed, in which the weld line is positioned differently. The results show the influence of the weld line on the forming behavior which is realized by the comparison of deep drawn monolithic parts with the deep drawn tailored welded blanks. While the monolithic parts could be formed without failure, the forming of tailored welded blanks was accompanied by cracks in dependency to the weld line orientation and the applied load in this region. The results also show that the failure occurs in the base material and that the weld line is not damaged by the applied load. After the characterization of the base materials and the weld material, a numerical modelling of the whole TWB could be realized in this work. Two different ways of modelling techniques of the weld line are compared and the necessity of the consideration of the weld line properties is demonstrated. Furthermore, in consideration of the weld line properties in the FE-Model, it is possible to show that the weld line resists the forming operation without failure.

The Stacking Fault Energy and its Dependence on the Interstitial Content in Various Austenitic Steels

2012 ◽  
Vol 706-709 ◽  
pp. 2193-2198 ◽  
Author(s):  
Lais Mujica ◽  
Sebastian Weber ◽  
Werner Theisen
Keyword(s):  
High Strength Steels ◽  
Intrinsic Property ◽  
High Strength ◽  
Electronic Configuration ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Austenitic Steels ◽  
Ε Martensite ◽  
The Individual ◽  
Interstitial Elements

The stacking fault energy (SFE) is an intrinsic property of metals and is involved in the deformation mechanism of different kind of steels, such as TWIP (twinning induced plasticity), TRIP (transformation induced plasticity), HNS (high nitrogen), and high strength steels. The dependence of the SFE on the content of interstitial elements (C, N) is not yet fully understood, and different tendencies have been found by different authors. In order to study the influence of the interstitial elements on the SFE, experimental measurements extracted from literature were collected and analyzed to predict the individual and combined effect of carbon and nitrogen in different systems. The referenced austenitic steels are Fe-22Mn-C, Fe-30Ni-C, Fe-15Cr-17Mn-N, Fe-18Cr-16Ni-10Mn-N, Fe-18Cr-9Mn-C-N, Fe-18Mn-18Cr-C-N and Fe-(20-30)Mn-12Cr-C-N. The calculation of the SFE is based on the Gibbs free energy of the austenite to ε-martensite transformation (ΔGγàε), which is calculated by means of the Calphad method. The revision of the measured values reveals that on different ranges of interstitial contents the SFE behaves differently. At lower values (C, N or C+N up to 0.4%), a local minimum or maximum is found in most of the systems. At higher concentration levels, a proportional dependence seems to occur. These observations agree with the theory of the dependence of SFE on the free electron concentration. Alloying with Mn or Ni has a strong influence on the electronic configuration and magnetic properties of the austenite and therefore on the SFE. The results of this study provide valuable information for materials design, especially in the context of alloying with C, N or C+N.

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