5 research outputs found

    Étude des synergies entre les procĂ©dĂ©s de fabrication additive et les procĂ©dĂ©s conventionnels pour la mise au point d'aciers Ă  hautes performances mĂ©caniques

    No full text
    Within the framework of the strong development of additive manufacturing carried by the CEA, this PhD work aims at studying the cold forming by conventional processes of additively manufactured blanks. This study focuses on determining the influence of the association between the process of elaboration by L-PBF (Laser – Powder Bed Fusion) and conventional cold-rolling on the microstructural and mechanical properties of the final products. In addition to the cold-rolling process, the impact of different heat treatments, of restauration and recrystallization, on the microstructural and mechanical properties is analyzed.vThis PhD work also proposes a study about the deformation modes of L-PBF consolidated 316L stainless steel, with a particular focus on mechanical twinning. The final objective of this work is to increase the knowledge about the microstructural and mechanical evolution of these materials consolidated by additive manufacturing, during conventional forming processes.Dans le cadre du fort dĂ©veloppement des procĂ©dĂ©s d’élaboration par fabrication additive portĂ©s par le CEA, ce travail de thĂšse a pour objectif d’étudier la mise en forme Ă  froid par des procĂ©dĂ©s conventionnels d’ébauches consolidĂ©es par fabrication additive. Cette Ă©tude vise Ă  dĂ©terminer l’influence de l’association entre les moyens d’élaboration par L-PBF (Laser – Powder Bed Fusion) et de mise en forme conventionnels par laminage sur les propriĂ©tĂ©s microstructurales et mĂ©caniques des produits finaux. Outre le procĂ©dĂ© de laminage Ă  froid, l’impact de diffĂ©rents traitements thermiques de restauration et de recristallisation sur les propriĂ©tĂ©s microstructurales et mĂ©caniques est analysĂ©. Ce travail de thĂšse propose Ă©galement une Ă©tude sur les modes de dĂ©formation de l’acier 316L consolidĂ© par L-PBF, avec une attention particuliĂšre portĂ©e sur le maclage mĂ©canique. L’objectif final de ce travail est d’offrir des Ă©lĂ©ments de comprĂ©hension sur les Ă©volutions des caractĂ©ristiques microstructurales et des propriĂ©tĂ©s mĂ©caniques de ces matĂ©riaux consolidĂ©s par fabrication additive au cours des procĂ©dĂ©s de mise en forme conventionnels

    Activated twinning variant determination in cold-rolled 316L stainless steel by effective Schmid factor analysis

    No full text
    International audienceA method is proposed to determine accurately the activated twinning variant during the cold-rolling of 316L stainless steel parts produced by L-PBF (Laser Powder Bed Fusion) from EBSD datas. The twinning variant selection is carried out by Schmid factor (SF) computations, using an effective Schmid factor for cold-rolling specifically. Schmid factor was proven to be a relevant parameter to predict the experimentally activated twinning variant. Additionally, cold-rolling deformation is shown to be composed by a strong compression component, along with a minor traction component. The effective Schmid factor is then modified accordingly to ensure a better prediction of twinned grains. Moreover, twinning Schmid factor analyses in traction and compression provide valuable information on the twinning activation regarding textured materials such as L-PBF 316L steel

    Competition between Metal Dissolution and Gas Release in Li-Rich Li 3 Ru y Ir 1– y O 4 Model Compounds Showing Anionic Redox

    No full text
    The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.chemmater.8b02955. Crystallographic data, additional Rietveld refinements, and EXAFS analysis (PDF) PDF cm8b02955_si_001.pdf (1.91 MB)International audienceLi-ion batteries have experienced tremendous progress over the past decade; however, their energy density should still be increased to power electric vehicles. Following this aim, the energy density of the cathode material can be drastically increased by making use of anionic redox, although it often comes along with material degradation. In this study, through a detailed analysis of the charge compensation mechanism of Li3RuO4 by online electrochemical mass spectrometry, X-ray absorption spectroscopy, and ultraviolet spectroscopy, we unveiled a new degradation mechanism for a cathode material showing anionic redox, namely the dissolution of Ru forming RuO4/RuO4– species with limited release of gas from the material. We show that this dissolution can be effectively tackled by substituting Ru with Ir. However, such a strategy leads to a massive increase in the release of O2 gas at the end of the charge. Density functional theory calculations prove that the relative stability of the end members RuO4 and IrO4 versus oxygen release is at the origin of this competition between metal dissolution and gas release

    Potential role of regulatory B cells in immunological diseases

    No full text
    corecore