TY - THES

T1 - Approach for the simulation of hydrogen diffusion in cold-worked high-strength multiphase steels in combination with experimental procedure

AU - Bergmann, Clemens

N1 - embargoed until 16-08-2018

PY - 2013

Y1 - 2013

N2 - Cold-worked, high-strength multiphase steels offer a promising automobile lightweight construction potential which can‘t be exploited due to their susceptibility to hydrogen embrittlement (HE) above tensile strengths of 1000 MPa. Hydrogen uptake of structural automotive steel parts may take place at three stages during their life cycle: along the steel coil processing lines (electrolytic galvanization), during the body in white production at the automotive producer (welding, pretreatment, cathodic dip painting) or during vehicle use (corrosion). In order to enable the safe use of those materials, industrially-relevant computational models will be developed in the EU-funded MultiHy project (www.multihy.eu), to evaluate the risk of hydrogen induced delayed fractures in automotive components. As a first step a HE-test procedure for test specimens was developed in the scope of this thesis, which enables the simulation of stress induced hydrogen diffusion within the specimen. Therefore the standardized HE-tests with U-bend, hole tensile and notched tensile specimens were modified, simulated and their utilizability for the MultiHy project was evaluated. This pioneering work resulted in the development of a very reducible HE-test, in which hydrogen-charged, notched tensile specimens are tested under constant load, in order to evaluate the HE-susceptibility of the tested steel. The arising stress and hydrogen diffusion thus facilitated was simulated in ABAQUS. The test method developed in this way was probed in a first field test with one of the concept materials of the MultiHy project.

AB - Cold-worked, high-strength multiphase steels offer a promising automobile lightweight construction potential which can‘t be exploited due to their susceptibility to hydrogen embrittlement (HE) above tensile strengths of 1000 MPa. Hydrogen uptake of structural automotive steel parts may take place at three stages during their life cycle: along the steel coil processing lines (electrolytic galvanization), during the body in white production at the automotive producer (welding, pretreatment, cathodic dip painting) or during vehicle use (corrosion). In order to enable the safe use of those materials, industrially-relevant computational models will be developed in the EU-funded MultiHy project (www.multihy.eu), to evaluate the risk of hydrogen induced delayed fractures in automotive components. As a first step a HE-test procedure for test specimens was developed in the scope of this thesis, which enables the simulation of stress induced hydrogen diffusion within the specimen. Therefore the standardized HE-tests with U-bend, hole tensile and notched tensile specimens were modified, simulated and their utilizability for the MultiHy project was evaluated. This pioneering work resulted in the development of a very reducible HE-test, in which hydrogen-charged, notched tensile specimens are tested under constant load, in order to evaluate the HE-susceptibility of the tested steel. The arising stress and hydrogen diffusion thus facilitated was simulated in ABAQUS. The test method developed in this way was probed in a first field test with one of the concept materials of the MultiHy project.

KW - hydrogen embrittlement

KW - hydrogen embrittlement test

KW - cold-worked high-strength multiphase steels

KW - hydrogen diffusion simulation

KW - Wasserstoffversprödung

KW - Wasserstoffversprödungstestverfahren

KW - kaltumgeformte höchstfeste Mehrphasenstähle

KW - Wasserstoffdiffusionssimulation

M3 - Diploma Thesis

ER -