Amélioration des propriétés physiques et mécaniques d'aciers TWIP FeMnXc : influence de la solution solide, durcissement par précipitation et effet composite

Abstract : TWIP steels deformation occurs by twinning and by dislocations gliding which leads to high a strain hardening. The deformation mechanisms are controlled by the stacking fault energy (SFE). A model for the prediction of the SFE and a law for TNéel (antiferro to paramagnetic transition) for austenite are proposed in FeMnXC systems (X = Cu, Cr, Al, Si et Ti). The studied FeMnCuC grades have a lower SFE than the Fe22Mn0,6C reference. The formation of [epsilon]-martensite replaces twinning without any deterioration of the mechanical properties. The flow stress decreases with the carbon content and the formation of [alpha]'-martensite at the lowest SFEs reduces the elongation to fracture. Substituting a part of the manganese content by copper leads to a 20% increase of the Young's Modulus at room temperature by decreasing TNéel below 0ºC. The precipitation of intragranular vanadium carbide increases the yield stress but does not influence the strain hardening rate. No interaction between precipitates and twins has been observed by microscopy. The coherency calculations and the TEM observations show that the carbides have an orientation relation with the austenite and are semi-coherent with a low residual coherency. The resulting stresses do not seem to be high enough to trap large quantities of hydrogen. The FeMnC + TiC alloys exhibit a strong hardening by composite effect at the beginning of deformation, while the strain hardening due to TWIP effect is not modified by the presence of the TiC particles. Meanwhile, cleavage occurs in the largest primary precipitates, which reduces the elongation to fracture
Document type :
Theses
Complete list of metadatas

Cited literature [53 references]  Display  Hide  Download

https://hal.univ-lorraine.fr/tel-01753017
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 2:04:34 PM
Last modification on : Monday, April 16, 2018 - 10:42:52 AM

File

2008_DUMAY_A.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01753017, version 1

Collections

Citation

Alexis Dumay. Amélioration des propriétés physiques et mécaniques d'aciers TWIP FeMnXc : influence de la solution solide, durcissement par précipitation et effet composite. Autre. Institut National Polytechnique de Lorraine, 2008. Français. ⟨NNT : 2008INPL014N⟩. ⟨tel-01753017⟩

Share

Metrics

Record views

22

Files downloads

33