On the damage criteria and their critical values for flowforming of ELI grade Ti64
TypeCommunications avec actes
Cold 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 translated along the tube axis, thus plastically deforming it. Flowforming of Ti-6Al-4V (also known as Ti64) is of great interest for improving the mechanical properties of the material, such as yield stress and fatigue strength. However this alloy is known to have poor ductility at room temperature. Therefore, flowforming of Ti64 without failure or crack is a great challenge. In this present paper, the authors have attempted to predict the different failure modes occurring during flowforming. An experimental machine has been built at the Center for Material Forming (CEMEF) in order to monitor the force on the single roller, the torque on the mandrel and the actual rotation speed of the roller as well. Numerous flowforming tests have been performed using different processing parameters, such as working depth, roller feed and initial geometry, in order to investigate the critical values which lead to the failure of the flowformed tube. In addition, numerical simulations of the process have been performed using the FORGE FEM solver. The results of the simulations have been used to evaluate the relevance of usual failure criteria (Crockford-Latham, Rice-Tracey and Oyane).
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MASSONI, Elisabeth; DEPRIESTER, Dorian (Trans Tech Publications, 2013)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 ...
MAYNADIER, Anne; LAVERNHE-TAILLARD, Karine; HUBERT, Olivier; DEPRIESTER, Dorian (Elsevier, 2014)Shape 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 ...
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MAYNADIER, Anne; LAVERNHE-TAILLARD, Karine; HUBERT, Olivier; DEPRIESTER, Dorian (Elsevier, 2011)The pseudo-elasticity of Shape Memory Alloys is due to a change in volumetric fraction between the high temperature phase (Austenite) and the low temperature phase (Martensite) under a mechanical loading. When a tensile ...
DEPRIESTER, Dorian; KUBLER, Régis (Slovenian Society for Stereology and Quantitative Image Analysis, 2019)The estimation of the grain size in granular materials is usually performed by 2Dobservations. Unfolding the grain size distribution from apparent 2D sizes is commonly referred as the corpuscle problem. For spherical ...