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.

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.

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.

Effect of Weld Location, Orientation, and Strain Path on Forming Behavior of AHSS Tailor Welded Blanks

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
S. K. Panda ◽  
J. Li ◽  
V. H. Baltazar Hernandez ◽  
Y. Zhou ◽  
F. Goodwin
Keyword(s):  
Plane Strain ◽  
Weld Line ◽  
High Strength ◽  
Deformation Mode ◽  
Dome Height ◽  
Manufacturing Cost ◽  
Stretch Forming ◽  
Material Combination ◽  
Tailor Welded Blanks ◽  
The Difference

Use of multiple advanced high strength steel sheets for fabrication of tailor welded blanks (TWBs) is one of the current interests for automotive and steel industries as it reduces manufacturing cost and weight of the vehicle, and also improves the quality of the component. As the varieties of TWB applications are increasing, the effects of the difference in material properties, weld, and its orientation on blank formability have become important both in deep drawing and stretch forming. In this work, high strength low alloy (HSLA) grade steels were laser welded with two different dual phase steels having 980 MPa (DP980) and 600 MPa (DP600) tensile strengths to fabricate two different material combination TWBs (DP980-HSLA and DP600-HSLA). Formability of these two types of TWBs has been studied experimentally both in biaxial and plane strain stretch forming modes by performing limiting dome height (LDH) tests using a 101.6 mm diameter hemispherical punch. Five different weld locations during biaxial-stretch forming mode, and the effect of weld orientation with respect to major principal strain in plane strain stretch forming mode, have been studied. It was found that formability LDH and failure location depended on weld location, and LDH increased when weld line was positioned at the extreme positions away from the center due to more uniform strain distribution on the deformed dome. The welded blanks had lower formability in plane strain deformation mode compared with biaxial-stretch forming mode. However, influence of weld orientation on the formability depended on material combination. Changes in the fracture mode were confirmed from fractography analysis of biaxial, transverse plane strain, and longitudinal plane strain stretch formed samples.

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 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].

Comparison of Material Behavior and Economic Effects of Cold and High Temperature Forming Technologies Applied to High-Strength Steels

2005 ◽  
Vol 6-8 ◽  
pp. 101-108 ◽  
Author(s):  
Reimund Neugebauer ◽  
Angela Göschel ◽  
Andreas Sterzing ◽  
Petr Kurka ◽  
Michael Seifert
Keyword(s):  
Elevated Temperatures ◽  
High Strength Steels ◽  
Dimensional Accuracy ◽  
High Strength ◽  
Economic Effects ◽  
Material Behavior ◽  
Spring Back ◽  
Forming Process ◽  
Cold Forming ◽  
Forming Tools

The focus of forming high-strength steel at elevated temperature is to improve its forming properties like elongation and to reduce the power requirements during the forming process in opposite to cold forming. Because of the undefined and large spring-back effects parts made by cold forming are not able to achieve the demanded dimensional accuracy, which is necessary for laser welding operations in car body assembly. The reduction of the spring-back behavior is another advantage of the temperature controlled forming technology. On the other side the forming at elevated temperatures requires increased costs for forming tools and tempering equipment. For a fundamental evaluation of this technology, expenditures for the complete process chain have to be considered.

Research Status of Warm Stamping Forming Technology at Domestic and International

2011 ◽  
Vol 314-316 ◽  
pp. 747-752
Author(s):  
Ming Deng ◽  
Yu Qin Wu ◽  
Lin Lv
Keyword(s):  
Aluminum Alloy ◽  
High Strength Steels ◽  
High Strength ◽  
Warm Forming ◽  
Spring Back ◽  
Research Status ◽  
Forming Technology ◽  
Drawing Test ◽  
The Status ◽  
Back Problem

This paper describes the research status of the warm stamping at home and abroad. The status of aluminum alloy and magnesium alloy is introduced in warm stamping respectively, using the tensile test, the drawing test, and bending experiments to prove the temperature and other factors have effect on the formability of materials. It also presents the status that using warm forming to solve the spring-back problem of the high strength steels. In addition, the mold and lubrication are also the key problems in warm stamping; they have a corresponding development with the development of warm forming though there are a few scholars specializing in the content.

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