177 research outputs found
Impact of experimental conditions on material response during forming of steel in semi-solid state
Semi-solid forming is an effective near-net-shape forming process to produce components with complex geometry and in fewer forming steps. It benefits from the complex thixotropic behaviour of semi-solids. However, the consequences of such behaviour on the flow during thixoforming, is still neither completely characterized and nor fully understood, especially for high melting point alloys. The study described in this paper investigates thixoextrusion for C38 low carbon steel material using dies at temperatures much lower than the slug temperature. Four different process parameters were studied: the initial slug temperature, the die temperature, the ram speed and the presence of a ceramic layer at the tool/material interface. The extruded parts were found to have an exact shape and a good surface state only if the temperature was below a certain value. This critical temperature is not an intrinsic material property since its value depends on die temperature and the presence of the Ceraspray©layer. Two kinds of flow were highlighted: a homogeneous flow controlled by the behaviour of the solid skeleton characterized by a positive strain rate sensitivity, and a non homogeneous flow (macro liquid/solid phase separation) dominated by the flow of the free liquid. With decreasing ram speed, heat losses increase so that the overall consistency of the material improves, leading to apparent negative strain rate sensitivity. Finally, some ways to optimise thixoforming are proposed
Influence de la vitesse de mise en forme et du cycle de chauffe sur le thixoforgeage des aciers
Analyse lâinfluence de la vitesse du coulisseau et de la tempĂ©rature du lopin (fraction liquide) sur le comportement de lâacier Ă lâĂ©tat semi-solide en utilisant un nouvel outillage de filage direct montĂ© sur une presse hydraulique. Cette nouvelle conception Ă©vite la dĂ©cĂ©lĂ©ration du vĂ©rin rapide pendant la mise en forme. Il permet donc des essais Ă vitesse constante. Ce travail sâintĂ©resse Ă©galement Ă lâĂ©coulement de la matiĂšre dans le cas du thixoforgeage de lâacier et montre lâimportance dâun couplage entre la tempĂ©rature initiale et la vitesse de dĂ©formation. Les diffĂ©rentes conditions permettant dâavoir un Ă©coulement homogĂšne et continu, avec un effort de mise en forme faible, sont Ă©tudiĂ©es et prĂ©sentĂ©es.This paper analyses the influence of two parameters (tool axis speed and billet temperature) on semi-solid steel alloy behaviour. A new design of direct filling tool is proposed and adapted on hydraulic press. This concept avoids the speed decrease during forming process. This works shows thermal exchange influence in thixoforging process in function speed raw and initial temperature inside the billet by analysis forming loads and part geometries
Impact of experimental conditions on material response during forming of steel in semi-solid state
Semi-solid forming is an effective near-net-shape forming process to produce components with complex geometry and in fewer forming steps. It benefits from the complex thixotropic behaviour of semi-solids. However, the consequences of such behaviour on the flow during thixoforming, is still neither completely characterized and nor fully understood, especially for high melting point alloys. The study described in this paper investigates thixoextrusion for C38 low carbon steel material using dies at temperatures much lower than the slug temperature. Four different process parameters were studied: the initial slug temperature, the die temperature, the ram speed and the presence of a ceramic layer at the tool/material interface. The extruded parts were found to have an exact shape and a good surface state only if the temperature was below a certain value. This critical temperature is not an intrinsic material property since its value depends on die temperature and the presence of the Ceraspray©layer. Two kinds of flow were highlighted: a homogeneous flow controlled by the behaviour of the solid skeleton characterized by a positive strain rate sensitivity, and a non homogeneous flow (macro liquid/solid phase separation) dominated by the flow of the free liquid. With decreasing ram speed, heat losses increase so that the overall consistency of the material improves, leading to apparent negative strain rate sensitivity. Finally, some ways to optimise thixoforming are proposed
Influence de la vitesse de mise en forme et du cycle de chauffe sur le thixoforgeage des aciers
Analyse lâinfluence de la vitesse du coulisseau et de la tempĂ©rature du lopin (fraction liquide) sur le comportement de lâacier Ă lâĂ©tat semi-solide en utilisant un nouvel outillage de filage direct montĂ© sur une presse hydraulique. Cette nouvelle conception Ă©vite la dĂ©cĂ©lĂ©ration du vĂ©rin rapide pendant la mise en forme. Il permet donc des essais Ă vitesse constante. Ce travail sâintĂ©resse Ă©galement Ă lâĂ©coulement de la matiĂšre dans le cas du thixoforgeage de lâacier et montre lâimportance dâun couplage entre la tempĂ©rature initiale et la vitesse de dĂ©formation. Les diffĂ©rentes conditions permettant dâavoir un Ă©coulement homogĂšne et continu, avec un effort de mise en forme faible, sont Ă©tudiĂ©es et prĂ©sentĂ©es.This paper analyses the influence of two parameters (tool axis speed and billet temperature) on semi-solid steel alloy behaviour. A new design of direct filling tool is proposed and adapted on hydraulic press. This concept avoids the speed decrease during forming process. This works shows thermal exchange influence in thixoforging process in function speed raw and initial temperature inside the billet by analysis forming loads and part geometries
Journal des Savants, 1957
Cézard Pierre. Journal des Savants, 1957. In: Romania, tome 79 n°316, 1958. pp. 545-546
Le Moyen Age, LX (4e série, t. IX), 1954
Cézard Pierre. Le Moyen Age, LX (4e série, t. IX), 1954. In: Romania, tome 76 n°302, 1955. pp. 275-276
Le Moyen Age, LXVI, 1960 (4e série, t. XV), 1-2
Cézard Pierre. Le Moyen Age, LXVI, 1960 (4e série, t. XV), 1-2. In: Romania, tome 84 n°335, 1963. pp. 418-421
Le Moyen Age, LXXV (4e série, t. XXIV), 1969, 1
Cézard Pierre. Le Moyen Age, LXXV (4e série, t. XXIV), 1969, 1. In: Romania, tome 93 n°371, 1972. pp. 419-420
BibliothĂšque de L'Ăcole des chartes, CXIII (1955)
CĂ©zard Pierre. BibliothĂšque de L'Ăcole des chartes, CXIII (1955). In: Romania, tome 78 n°310, 1957. p. 266
Studier i modern SprÀkvetenskaf, XVII (1949)
C. P. Studier i modern SprÀkvetenskaf, XVII (1949). In: Romania, tome 72 n°288, 1951. p. 549
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