A method to evaluate the formability of high-strength steel in hot stamping

Cui, Junjia; Sun, Guangyong; Xu, Junrui; Huang, Xiaodong; Li, Guangyao

doi:10.1016/j.matdes.2015.04.009

Cited by 64 publications

(22 citation statements)

References 30 publications

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“…The aim of the test is to set and record the deformation under defined strain combinations using specimen geometries of different widths. Since the flow properties and the forming limit of a material both strongly depend on the forming temperature, conventional FLC do not adequately describe the forming limit of a sheet material during hot forming [9]. To perform temperature controlled FLC above 500 °C, various approaches can be found in literature, where modified Nakajima set-ups are used [10][11][12].…”

Section: State Of the Artmentioning

confidence: 99%

Hot forming limit curves for numerical press hardening simulation of AISI 420C

Behrens

Uhe

Wester

et al. 2020

METAL 2020 Conference Proeedings

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A possible alternative to the established press hardening steel 22MnB5 are hot formed martensitic chromium steels. Both strength and ductility of the martensitic chromium steels can reach very high values with appropriate heat treatments. Therefore, car body parts with high crash safety can be produced by hot forming martensitic chromium steels. To identify the formability of a sheet metal, forming limit curves are state of the art. Conventional forming limit curves are recorded at room temperature and do not adequately describe the forming capacity for hot sheet metal forming as it strongly depends on temperature. Therefore, in this paper, an experimental-numerical method for determining quasi-isothermal FLC at high forming temperatures is applied to the martensitic chromium steel AISI 420C (X46Cr13) for forming temperatures between 750-1,050 °C according to its process route. The results show an increase of the formability with rising forming temperature with the highest at 1,050 °C.

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Section: State Of the Artmentioning

confidence: 99%

Hot forming limit curves for numerical press hardening simulation of AISI 420C

Behrens

Uhe

Wester

et al. 2020

METAL 2020 Conference Proeedings

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show abstract

“…The material behavior of hot-stamped steels has been previously investigated extensively [1,2]. However, the description of friction in the FE simulations of hot stamping processes is usually oversimplified by the use a constant Coulomb friction coefficient (COF) [1,[3][4][5]; consequently, the actual conditions are not well represented. The description of these conditions is the focus of this study.…”

Section: Introductionmentioning

confidence: 99%

Multiscale friction model for hot sheet metal forming

et al. 2021

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The accurate description of friction is critical in the finite element (FE) simulation of the sheet metal forming process. Usually, friction is oversimplified through the use of a constant Coulomb friction coefficient. In this study, the application of an existing multiscale friction model is extended to the hot stamping process. The model accounts for the effects of tool and sheet metal surface topography as well as the evolution of contact pressure, temperature, and bulk strain during hot stamping. Normal load flattening and strip drawing experiments are performed to calibrate the model. The results show that the model can relatively well predict friction in strip draw experiments when the tool surface evolution due to wear is incorporated. Finally, the application of the formulated multiscale friction model was demonstrated in the FE simulation of a hot-stamped part.

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“…This implies that it is impossible to measure the deformed principal strains. In order to obtain the FLD at elevated temperatures, Cui et al 19 applied the equation of Abspoel et al 20 based on special points from various tests including uniaxial tension, plane strain, and biaxial stretching. Other studies developed damage models, such as continuum damage mechanics (CDM), modified Gurson-Tvergaard-Needleman (GTN) model, and other models, to predict thermal FLD based on identified input parameters and then compared the same with those in corresponding experiments.…”

Section: Introductionmentioning

confidence: 99%

Combined numerical and experimental study to predict the forming limit curve of boron steel sheets at elevated temperatures

Nguyen

Kim

2019

Proceedings of the Institution of Mechanical Engineers, Part B:

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The aim of this study involved evaluating and predicting forming limit curves of boron steel 22MnB5 sheet at elevated temperatures. A finite-element method simulation was adopted based on ductile fracture criteria and simple experiments at elevated temperatures. First, tensile experimental data and ductile fracture criterions of Johnson–Cook and ductile void growth models were input to ABAQUS/Explicit software to predict and compare the same with fracture occurrence in experiments performed via Hecker’s punch stretching tests at room temperature. Subsequently, punch stretching test data at room temperature were added to correct the fracture strain locus in the space of the stress triaxiality and the equivalent strain following the ductile void growth model. After confirming the accuracy of the forming limit curve prediction at room temperature, fracture strain loci at high temperatures using ductile void growth model were determined based on the average ratio between the fracture equivalent plastic strains at room temperature as well as higher temperatures. Finally, Hecker’s punch stretching tests were numerically simulated to predict forming limit curve(s) of boron steel 22MnB5 sheet at high temperatures.

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A method to evaluate the formability of high-strength steel in hot stamping

Cited by 64 publications

References 30 publications

Hot forming limit curves for numerical press hardening simulation of AISI 420C

Hot forming limit curves for numerical press hardening simulation of AISI 420C

Multiscale friction model for hot sheet metal forming

Combined numerical and experimental study to predict the forming limit curve of boron steel sheets at elevated temperatures

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