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Drillet, Pascal

Grigorieva, Raisa

Jacques, Pascal

Krid, Mohamed

Mandy, Mélodie

Sturel, Thierry

English

Engineering Conferences International

ANALYSIS OF HYDROGEN ABSORPTION - DESORPTION MECHANISMS IN AL-SI COATED HIGH STRENGTH STEEL DURING HOT STAMPING PROCESS   Mohamed Krid, Université catholique de Louvain, Institute of Mechanics, Materials and Civil Engineering, Belgium Mohamed.krid@uclouvain.be Mélodie Mandy, CRM group, 4000 Liège, Belgium  Thierry  Sturel, ArcelorMittal Global R&D, 57283 Maizières-lès-Metz Cedex, France Raisa Grigorieva, ArcelorMittal Global R&D, 57283 Maizières-lès-Metz Cedex, France  Pascal Drillet, ArcelorMittal Global R&D, 57283 Maizières-lès-Metz Cedex, France Mélodie  Pascal Jacques, Université catholique de Louvain, Institute of Mechanics, Materials and Civil Engineering, IMAP, 1348 Louvain-la-Neuve, Belgium   Key Words: Deuterium, Al-Si coating, microstructure, Thermal Desorption Analysis  Press hardenable steels (PHS) coated with Al-Si alloy are widely used in the automotive industry owing to their good mechanical properties (yield strength > 1200 MPa and tensile strength > 1500 MPa). The presence of Al-Si coating prevents oxidation and decarburization of steel during austenitization. It has been found that aluminized PHS are more sensitive to hydrogen absorption during austenitization in comparison to uncoated PHS. After quenching, Al-Si coating indeed acts as a hydrogen-diffusion barrier at room temperature and the diffusible hydrogen present in aluminized PHS can lead to hydrogen embrittlement before painting (e-coating). The purpose of this study is to analyze the main mechanisms that govern the rate of hydrogen uptake and desorption in coated PHS. In order to assess the role of the alloying elements and/or of the phases constituting the coating in the hydrogen uptake and desorption, two systems made of 22MnB5 steel and coated with either pure Al or Al-9%wt. Si alloys were processed. Austenitization of samples was carried out in controlled atmosphere containing D2O instead of H2O in order to avoid any atmospheric contamination which could compromise further accurate quantification. Thermal desorption analysis (TDA), coupled with microstructural characterization by scanning electron microscopy (SEM) and X-ray diffraction (XRD), have allowed to determine that deuterium uptake in Al coated steel is higher than in Al-Si coating and occurs after coating melting. Owing to a specific methodology, we demonstrate that some of the deuterium is trapped within the Al-Si coating, but not in the case of the Al coating. Finally, the D2 desorption profiles of aluminized steels are explained by diffusion of D through different phases of the coating and are also affected by the presence of bare edges.   

Analysis of hydrogen absorption - desorption mechanisms in Al-Si coated high strength steel during hot stamping process

https://dc.engconfintl.org/cgi/viewcontent.cgi?filename=0&article=1062&context=hydrogen&type=additional

Analysis of hydrogen absorption - desorption mechanisms in Al-Si coated high strength steel during hot stamping process

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Engineering Conferences International