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Caractérisation de la tenue mécanique en fatigue de pièces en alliage de titane Ti-5Al-5V-5Mo-3Cr contenant des défauts

Abstract : The prediction of the fatigue life of sliders made by SAFRAN Landing Systems is the goal of this work. To manufacture big forged parts, high performance Ti-5Al-5V-5Mo-3Cr (Ti5553) alloy is used.To ensure the in-service life, various mechanical treatments are carried out. Shot-peening at the end of the process is of prime importance in order to improve the mechanical performance. The knowledge of residual stresses resulting from this treatment is necessary to understand fatigue results for all part location. The two-phase microstructure of the alloy makes stress analyses difficult. A complete protocol to analyse stresses by X-ray diffraction has been developed and validated through in-situ test. The Ti5553 alloy exhibits high yield stress coupled with weaker toughness. Lifing of parts made of Ti5553 is currently carried out with no specific account of surface defects. To improve the knowledge of initiation processes in this alloy in the presence of defects, various tests have been carried out (elasto-plastic behavior, crack initiation and propagation studies). Tests are carried out on coupons with faces and edges with calibrated defects (i.e., machined scratches and indents). The influence of such defects on the fatigue lifetime are studied in terms of type, size and shot-peening level.
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https://tel.archives-ouvertes.fr/tel-01841469
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Submitted on : Tuesday, July 17, 2018 - 12:37:43 PM
Last modification on : Tuesday, October 6, 2020 - 8:24:06 AM
Long-term archiving on: : Thursday, October 18, 2018 - 2:12:42 PM

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  • HAL Id : tel-01841469, version 1

Citation

Benoit Voillot. Caractérisation de la tenue mécanique en fatigue de pièces en alliage de titane Ti-5Al-5V-5Mo-3Cr contenant des défauts. Mécanique des solides [physics.class-ph]. Université Paris-Saclay, 2018. Français. ⟨NNT : 2018SACLN012⟩. ⟨tel-01841469⟩

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