Submicrocristalline structure and dynamic recovery of cold flowformed ELI grade Ti-6Al-4V
Communication avec acte
Flowforming is a means to produce seamless tubes by plastic deformation at room temperature. It consists in reducing the thickness of a tubular part mounted on a mandrel by deforming it using several rollers translating along the tube axis, while the tube is rotating along its axis. Thanks to the high compressive stresses, and to the incremental nature of the deformation process, flowforming can lead to a high thickness reduction and thus to high elongation of the deformed tubes. Ti-6Al-4V (Extra Low Interstitial grade) tubes have been deformed by cold flowforming, with a thickness reduction ratio higher than 60%, and their microstructures have been investigated using light optical microscopy (LOM), scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). Based on EBSD data, a post-processing analysis has been performed in order to study the texture of the flowformed parts. Optical Microscopy showed that the material could be deformed without displaying flow instability such as adiabatic shear banding, despite the fact that it has been processed out of the stable processing maps (high strain rate and low temperature). It also evidenced a major deformation along the tube axis accompanied with a slight twist due to torsion stress. EBSD analysis indicated the occurrence of continuous dynamic recrystallization, which is rarely reported in the α-β domain of such alloys. The recovery/ recrystallization effects resulted in a submicrocrystalline equiaxed structure, which is consistent with that previously reported for Ti-6Al-4V subjected to severe plastic deformation (SPD). The texture of the hexagonal α-phase appeared to be similar to that obtained on extruded Ti-6Al-4V, with a basal component perpendicular to the tube axis
Cette publication figure dans le(s) laboratoire(s) suivant(s)
Visualiser des documents liés par titre, auteur, créateur et sujet.
Communication avec acteCold flowforming is a chipless forming process that deforms tubular parts by reducing their outer diameter and thickness while increasing their length. It consists of a rotating mandrel and one or more rollers that are ...
Radical Voronoï tessellation from random pack of polydisperse spheres: Prediction of the cells’ size distribution Article dans une revue avec comité de lectureDEPRIESTER, Dorian; KUBLER, Régis (Elsevier, 2019)This paper investigates the relevance of the representation of polycrystalline aggregates using RadicalVoronoï(RV)tessellation,computedfromRandomClosePacks(RCP)ofsphereswithradiusdistributionfollowing a lognormal distribution. ...
Article dans une revue avec comité de lectureShape Memory Alloys (SMAs) undergo an austenite–martensite solid–solid phase transformation which confers its pseudo-elastic and shape memory behaviours. Phase transformation can be induced either by stress or temperature ...
Grain size estimation in polycrystals: Solving the corpuscle problem using Maximum Likelihood Estimation Article dans une revue avec comité de lectureIn materials science, the microstructures of materials are generally characterized by 2D observation (e.g. electron microscopy). For polycrystalline materials, such as crystalline rocks or ceramics, those observations can ...
Article dans une revue avec comité de lectureROLLAND DU ROSCOAT, Sabine; ORGÉAS, Laurent; GEINDREAU, Christian; LEVRARD, Benjamin; BRÉMOND, Florian; DEPRIESTER, Dorian (Wiley, 2022)Modelling the physical behaviour of fibrous materials still remains a great challenge because it requires to evaluate the inner structure of the different phases at the phase scale (fibre or matrix) and the at constituent ...