Qualification of the in-situ bending technique towards the evaluation of the hydrogen induced fracture mechanism of martensitic Fe-C steels

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:792

Article

Pinson, M.¹  Springer, H.^2,3  Depover, T.¹  Verbeken, K.¹ 

[1] Ghent Univ UGent, Dept Mat Text & Chem Engn, Technol Pk 46, B-9052 Ghent, Belgium

[2] Rhein Westfal TH Aachen, Inst Bildsame Formgebung, Intzestr 10, D-52056 Aachen, Germany

[3] Max Planck Inst Eisenforsch GmbH, Dept Microstruct Phys & Alloy Design, Max Planck Str 1D, D-40237 Dusseldorf, Germany

关键词: In-situ bending test;    Hydrogen embrittlement;    Fe-C steels;    Martensite;    Fractography;   

DOI  :  10.1016/j.msea.2020.139754

来源: Elsevier

【 摘 要 】

This paper proposes a new in-situ hydrogen (H) charging bending technique to investigate the susceptibility to hydrogen embrittlement (HE) of high strength steels with limited ductility. The methodology is tested with generic martensitic Fe-C steels with a carbon (C) content of 0.2 wt%, 0.4 wt% and 1.1 wt%, respectively. The in-situ bending technique is developed to evaluate the hydrogen susceptibility of these brittle materials and is compared to uncharged samples as a reference. Moreover, as a crucial step in the validation of the technique, a comparison with conventional in-situ tensile testing for the most ductile material (i.e. Fe-0.2C) is performed. The bending results show that charging with H causes a significant ductility loss, which is characterized by a transition from a microvoid (Fe-0.2C), intergranular (Fe-1.1C) or mixed (Fe-0.4C) fracture surface for the uncharged samples to a hydrogen induced cleavage fracture appearance with additional cracking. The transition to the cleavage fracture type is found to be caused by the Hydrogen Enhanced Plasticity Mediated Decohesion mechanism, indicating that hydrogen is preferentially trapped at packet or block boundaries in high carbon steels without alloying additions. The fracture surface of the Fe-0.2C alloy after in-situ tensile testing was very similar to the fracture surface obtained after in-situ bending testing, which indicates that the fracture mode during bending is mainly dominated by the tensile field. This supports the applicability of the in-situ bending technique for intrinsically brittle materials.

【 授权许可】

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