Impact of Alloying Design on the Crash Relevant Material Properties of Press Hardening Steel based on Mn-B Concept

Tailored press-hardening processes are used to reduce both production costs and component weight. The aim of these development methods is to generate regions zones in the component with both high and low tensile strengths. The B-pillar, for instance, needs high tensile strength in the region of the roof frame to prevent deformation. However, the connection to the body should have lower tensile strength to absorb the energy of a crash.Regarding the production process for tailored welded blanks, the tailored press-hardening processes for monolithic sheets need no joining operation. As an addition to recent publications, this paper presents a modified tailored press-hardening process, with a modified time-temperature process. Starting from the required tailored material properties of the part, with a sheet thickness of 1.5 mm, research has been done on the process window and process design.This contribution concentrates on modifications to the time-temperature profile. After heating the hot-dip galvanized, heat-treatable 22MnB5 steel above its austenitic temperature, the aim is to adjust the material’s mechanical properties within the cooling process.Based on the continuous TTT diagram, the cooling rate has an impact on the material’s mechanical material properties. Different proportions of constituents such as Bainite, Ferrite or Perlite are created by varying the cooling rate. Furthermore, during an intermediate stage in the cooling-down period, the holding temperature has an even stronger effect on the material’s microstructural composition and the corresponding mechanical properties. The rate of the transformation process changes, depending on the intermediate temperature. The third parameter investigated is the holding time at this intermediate temperature. As the holding time is increased a transformation, progressing from austenite to other constituents, can be observed.The results of this parametric study could be transferred to a prototype environment.

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Influence of Hot Rolling Process on the Microstructure and Mechanical Properties of a Press Hardening Steel

Materials Performance and Characterization ◽

10.1520/mpc20160120 ◽

2017 ◽

Vol 6 (1) ◽

pp. 20160120

Author(s):

Kuanhui Hu ◽

Guifeng Zhou

Keyword(s):

Mechanical Properties ◽

Hot Rolling ◽

Rolling Process ◽

Press Hardening ◽

Hot Rolling Process ◽

Microstructure And Mechanical Properties ◽

Press Hardening Steel

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Predicting the thermoelastic response and relevant material properties of SMC

Journal of Materials Processing Technology ◽

10.1016/0924-0136(95)01879-4 ◽

1996 ◽

Vol 56 (1-4) ◽

pp. 655-667 ◽

Cited By ~ 1

Author(s):

J.F. Dywer ◽

J.M. Dulieu-Smith ◽

P. Stanley

Keyword(s):

Material Properties ◽

Thermoelastic Response ◽

Relevant Material

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Recent Developments in LS-DYNA to close the Virtual Process Chain for Forming, Press Hardening and Welding

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.651-653.1312 ◽

2015 ◽

Vol 651-653 ◽

pp. 1312-1318 ◽

Cited By ~ 1

Author(s):

Thomas Klöppel ◽

Andrea Erhart ◽

André Haufe ◽

Tobias Loose

Keyword(s):

Material Properties ◽

Manufacturing Industry ◽

Plastic Material ◽

Base Material ◽

Process Chain ◽

Press Hardening ◽

Multistage Processes ◽

Recent Developments ◽

Material Formulation ◽

Virtual Process

Forming, press hardening and welding are a well-established production processes in manufacturing industry, but predicting the finished geometry and the final material properties of the processed parts is still a major issue. In particular, deformations caused by welding are often neglected in the virtual process chain, although they have to be compensated for in order to fulfill the requirements on shape tolerance. This presentation will give an overview on novel features of LS-DYNA implemented particularly for welding simulations.To begin with, new keywords will be presented that allow applying the heat generated by the weld torch. LS-DYNA offers a very convenient way to define the well-known Goldak heat source, but it is also possible to define arbitrarily shaped torch geometries.In order to obtain a predictive model for welding simulations, specific material models have been devised in LS-DYNA. The properties of filler material in weld seams are accounted for by a ghost material approach. Material is initialized as ghost material and is activated, i.e. it is given base material properties, when the temperature reaches the melting point. This approach has been implemented for a relatively simple thermo-elasto-plastic material formulation *MAT_CWM as well as for the more complex material law *MAT_UHS_STEEL. The latter has initially been implemented for press hardening simulations and is able to predict the microstructure of steel alloys including phase transformations and the resulting mechanical properties.In this contribution, details of the material formulations and novel features are presented. Examples will demonstrate how these features can be applied to multistage processes including several forming and welding stages.

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Determination of Material/Geometry of the Section Most Adequate for a Static Loaded Beam Subjected to a Combination of Bending and Torsion

Materials Science Forum ◽

10.4028/www.scientific.net/msf.730-732.507 ◽

2012 ◽

Vol 730-732 ◽

pp. 507-512 ◽

Cited By ~ 3

Author(s):

Hugo Miguel Silva ◽

José Filipe Bizarro de Meireles

Keyword(s):

Finite Element ◽

Material Properties ◽

Model Updating ◽

Material Selection ◽

Young Modulus ◽

Element Model ◽

Mechanical Tests ◽

Correct Operation ◽

Short Period ◽

Relevant Material

The acceleration of industrial machines mobile parts has been increasing over the last few years, due to the need of higher production in a short period of time. The machines were dimensioned for a lower value of acceleration, which means there is not enough rigidity for the correct operation at much higher accelerations. Nowadays, the accelerations can be near 12 times the acceleration of gravity. There is the need of improving rigidity to make possible the correct machine operation without undesired vibrations that can ultimately lead to failure. The main applications of this work are plotters and laser cutting machines. To improve rigidity, one must improve the relevant material properties, and the relevant geometric variables of the model.[1] A novel Finite Element Model Updating methodology is presented in this paper. The considered models were : a ribbed plate and a tubular beam. The models were built by means of the Finite Element Method (FEM), and MATLAB was used to control the optimization process, using a programming code. Both material properties and geometric parameters were optimized. The main aim of the materials modeling is to know how the value of the objective function changes with the value of the material properties. Materials selection was performed, using material selection charts, to select the best material for the application. The value of these properties was not in the catalogue, and the properties used to perform the material selection were related to a material sub-class, Eg. Steel. The final material selection determined the best specific material for the application, and that material was mechanically tested. The mechanical tests performed were: Tensile Test and Extensometry Test, to obtain the relevant material properties, mainly Young Modulus, Poisson Coefficient and Yield Stress. The deflection of the optimized models reduced strongly in comparison to the initial models.

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