Abstract
For several years, Inconel 718 made by Laser Beam Melting (LBM) has been used for components of the Ariane propulsion systems manufactured by ArianeGroup. In the aerospace field, many components of space engines are used under hydrogen environment. The risk of hydrogen embrittlement (HE) can be therefore a first order problem. Consequently, to improve the HE sensitivity of LBM Inconel 718, a systematic approach needs to be developed to characterize the microstructure at different scales and its interaction with hydrogen. This study addresses the impact of gaseous hydrogen on the material mechanical behavior under fatigue loadings. In a first step, the low cycle fatigue behavior under 300 bar of hydrogen gas has been evaluated with specimen loaded at a constant load ratio of R=0.1 and a frequency of 0.5 Hz. A reduction in the cycle number of fracture is shown. This reduction of fatigue life is a consequence of the impact of hydrogen damage processes. The impact of hydrogen is evaluated at the stages of crack initiation, crack propagation. These results are discussed in relation with the hydrogen embrittlement mechanisms and particularly in terms of hydrogen / plasticity interactions. To achieve this, the fracture surface morphology was first examined using scanning electron microscopy and second samples near the fracture surface were extracted using Focused-Ion Beam machining from regions containing striation. The main result observed is a reduction of the size of dislocation organization in relation with a decrease of the striation distance.
Highlights
Inconel 718 made by Laser Beam Melting (LBM) has been used for components of the Ariane propulsion systems manufactured by ArianeGroup
This study addresses the impact of gaseous hydrogen on the material mechanical behavior under fatigue loadings
This study will focus on the fatigue behavior under hydrogen pressure of a material used for the Ariane propulsion systems manufactured by ArianeGroup
Summary
This study will focus on the fatigue behavior under hydrogen pressure of a material used for the Ariane propulsion systems manufactured by ArianeGroup. This is an Inconel 718 nickel based super alloy made by laser beam melting process (LBM). No study has been conducted to evaluate the impact of gaseous hydrogen on the mechanical behavior of Inconel 718 obtained by additive manufacturing method. The impact of hydrogen on the damage process will be discussed with regard to the different stages of damage (crack initiation, crack propagation, toughness) Each of these damage steps has been studied using observations under a scanning electron microscope. The hydrogen / plasticity interactions during the crack growth process are discussed using samples extracted by Focused-Ion Beam machining from regions containing striation
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have