Local hydrogen accumulation after cold forming and heat treatment in punched advanced high strength steel sheets

Drexler, Andreas; Bergmann, C.; Manke, Gregor; Kokotin, V.; Mraczek, Klemens; Leitner, Silvia; Pohl, M.; Ecker, Werner

doi:10.1016/j.jallcom.2020.158226

Cited by 22 publications

(10 citation statements)

References 62 publications

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“…Trapped hydrogen can be regarded as reversibly trapped, whenever hydrogen absorption and/or desorption occur without significant microstructural changes at the sample surface. Typical reversible hydrogen trapping sites are directly accessible from the lattice sites, such as vacancies [25,36,38,39], dislocations [25,38,40], grain boundaries [36,38,41] or carbide interfaces [42][43][44][45][46]. According to McNabb and Foster [47], lattice hydrogen diffuses freely through the crystal structure, but trapped hydrogen exchanges only locally with lattice hydrogen.…”

Section: Bulk Diffusion Modellingmentioning

confidence: 99%

“…Fitting the predictions of the bulk diffusion model to the measured TDS spectrum enables determining the binding energy, the trap density and the migration energy [20,25,38,42,43]. For that purpose, the bulk diffusion as given in Eq.…”

Section: Bulk Diffusion Modellingmentioning

confidence: 99%

“…The slower the loading rate, the longer is the total test duration. Typical hydrogen embrittlement tests may run for days to weeks [13,20,21,25]. During this time, hydrogen is desorbing from the surface of charged samples, which causes hydrogen diffusion-related difficulties in experimental testing and evaluation of internal hydrogen embrittlement.…”

Section: Introductionmentioning

confidence: 99%

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The role of hydrogen diffusion, trapping and desorption in dual phase steels

et al. 2022

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Hydrogen embrittlement (HE) of advanced high-strength steels is a crucial problem in the automotive industry, which may cause time-delayed failure of car body components. Practical approaches for evaluating the HE risk are often partially and contradictive in nature, because of hydrogen desorption during testing and inhomogenous hydrogen distributions in, e.g., notched samples. Therefore, the present work aims to provide fully parametrized and validated bulk diffusion models for three dual phase steels to simulate long-range chemical diffusion, trapping and hydrogen desorption from the surface. With one constant set of parameters, the models are able to predict the temperature dependency of measured Choo-Lee plots as well as the concentration dependency of measured effective diffusion coefficients. Finally, the parametrized and validated bulk diffusion models are applied for studying the role of the current density on the permeation time and the role of coatings as effective diffusion barriers. Graphical abstract

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Section: Bulk Diffusion Modellingmentioning

confidence: 99%

Section: Bulk Diffusion Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The role of hydrogen diffusion, trapping and desorption in dual phase steels

et al. 2022

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“…For evaluating the role of the material strength on the HE susceptibility, smooth tensile samples were charged with hydrogen. In contrast to notched sample geometries, smooth samples have homogenous stress distribution, since they do not face the problem of hydrogen accumulation by maxima in the hydrostatic stress fields and by localized plastic deformation at the notch [2,3,26]. For guaranteeing also homogeneous hydrogen distribution after charging, the minimum time to reach saturation was determined as shown in Figure 3a.…”

Section: Characterization Of Basic Mechanical Propertiesmentioning

confidence: 99%

“…Thus, the lightweight potential of AHSS sheets cannot be fully exploited and certain protective measures must be considered. Cold forming [2] and punching [3,4] are crucial with respect to HE susceptibility of AHSS sheets, as plastic deformation may increase the solubility [3] and decreases the chemical diffusivity [5,6] of hydrogen. Zones of plastic deformation act like "sponges" and hydrogen accumulates up to five-times more than in bulk zones [3,4,7].…”

Section: Introductionmentioning

confidence: 99%

Influence of Plastic Deformation on the Hydrogen Embrittlement Susceptibility of Dual Phase Steels

Drexler

Helic

Silvayeh

et al. 2022

KEM

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The susceptibility of advanced high-strength steels (AHSS) to hydrogen embrittlement (HE) limits the broad utilization of these materials for body-in-white (BIW) components. The considerable decrease of both ductility and toughness due to local hydrogen accumulation inside of formed components may cause unpredictable time-delayed failure. In particular deep-drawn and punched AHSS components are prone to hydrogen absorption. This work investigates the influence of plastic deformation on hydrogen absorption of dual phase (DP) steels. For that purpose, tensile samples were machined out of three commercial 1.2 mm-thick DP sheets with ultimate tensile strengths of 626 MPa, 826 MPa and 1096 MPa. Samples were uniaxially pre-strained to 2 %, 5 %, 10 %, 15 % and 20 %. After pre-straining the samples were electrochemically charged with hydrogen, and the actual hydrogen contents were determined using a thermal desorption analyser (TDA). Before and after charging, the hardness of the samples was measured and the uniaxial quasi-static tensile properties were determined. In order to quantify the influence of plastic deformation on HE, slow strain rate tests (SSRT) were performed. The results of the tests were correlated with the fraction of martensite determined for each of the three steels.

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PVD coated dies in action: Exploring finite element analyses for sheet metal forming of high‐strength steel

Sivarajan,

Neto,

Oliveira

et al. 2024

Lubrication Science

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This research proposes a complete analysis of the use of physical vapour deposition coated dies in the sheet metal forming process for high‐strength‐steel sheets. The goal of the proposed approach is to investigate how PVD coatings affect die performance and how that affects the formability and quality of the high‐strength‐steel‐sheets that are made. The finite element analyses are used to simulate and evaluate the mechanical behaviour and deformation characteristics during the forming process. Studies to enhance the forming characteristics of these materials, typically denoted by limiting draw ratio and maximum punch force are required. A reduction in punch force required and improved limiting draw ratio is observed that is attributed to the enhanced contact with friction‐conditions in the die‐sheet interfaces. The experimental results are compared with simulation results from DD3IMP, a code used for deep drawing simulations, and it is evident that the experimental outcomes are analysed well with the simulation results.

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Local hydrogen accumulation after cold forming and heat treatment in punched advanced high strength steel sheets

Cited by 22 publications

References 62 publications

The role of hydrogen diffusion, trapping and desorption in dual phase steels

The role of hydrogen diffusion, trapping and desorption in dual phase steels

Influence of Plastic Deformation on the Hydrogen Embrittlement Susceptibility of Dual Phase Steels

PVD coated dies in action: Exploring finite element analyses for sheet metal forming of high‐strength steel

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