. .. Post-weld-heat-treatment,

. .. Sdic), Stereo Digital Image Correlation

. .. Results, 3.1 Microstructure: EBSD analysis for location of the WCZ, ? crystal lattice orientation and PM texture analysis

. .. , 229 7.3.4 Normalized strain rate field and plastic activity tracking for the LFW-AW-PC tensile specimen, DIC strain field measurement and localization

.. .. Fatigue,

.. .. Discussion,

.. .. Conclusions,

, LFW-AW-PC (red) and PWHT (black) joints, Effect of defects and weak zones on mech. props. of dissimilar Ti17-Ti64 LFW joints. 6.7 Microhardness profiles across the WCZ for the three configurations: the LFW-AW (green)

. .. , LFW-AW-PC (red) and PWHT (black) joints, Macroscopic engineering stress-strain curves for the three configurations: the LFW-AW (green), p.205

, 10 a) Fractographic observation of the the LFW-AW-1 tensile specimen showing mostly b) pseudo brittle fracture and some c) elongated dimples of "unstable" ductile rupture at the Ti17 TMAZ next to the DL. d) EDX point analysis of the fracture surface showing an approximation of the %wt. content of the PM alloying elements and Cu. Notice that some Cu is found despite the fact that this element does not belong to either PM nominal chemical composition, Cumulated strain maps, (b-g) cumulated strain spatio-temporal graphs, (d-i) normalized strain rate maps, vol.6

, Fractographic observations showing ductile rupture at the Ti64 PM (P = ?7.5 mm) of the of the LFW-AW-PC-1 tensile specimen

, Fractographic observations showing "unstable" ductile rupture at the Ti17 TMAZ of the of the LFW-AW-PC-2 tensile specimen

. .. , S-N curve of the LFW-AW-PC fatigue specimens (R = 0.1), p.211

, Fractograph of a typical LFW-AW-PC fatigue specimen showing b) elongated dimples; c) primary and d) secondary fatigue crack initiation sites, p.212

, Literature review concerning the surface preparation for linear friction welding, p.215

. .. , Fractographic analysis of the LFW-AW-PC-2 CT specimen, p.216

, Literature review concerning the surface preparation for linear friction welding, p.219

. .. Results, 3.1 Microstructure: EBSD analysis for location of the WCZ, ? crystal lattice orientation and PM texture analysis

. .. , 229 7.3.4 Normalized strain rate field and plastic activity tracking for the LFW-AW-PC tensile specimen

, Strain to failure and failure location

.. .. Fatigue,

.. .. Discussion,

. .. Conclusions, 244 7.3 EBSD mappings over the gage length of three tensile specimens: a) PM-1, b) crossweld LFW-AW-PC-1 and c) cross-weld PWHT-1. d) Frame of reference, schematic view of the mapped region, inverse pole figure and texture analysis for the PM extrusion axis (001). e) EBSD mapping for the PM in the PWHT-1 tensile specimen highlighting coarsen ? precipitates and f) optical view of the former WCZ in the PWHT-1 tensile specimen

, 241 7.5 a-c-e) Tensile tests, b-d-f) ? PP cumulated strain fields and Schmid's factor mappings for the tensile specimens: a-b) PM-1, c-d) LFW-AW-PC-1 and e-f) PWHT-1. . . . 242 the LFW-AW-PC-2 tensile specimen. and b) spatio-temporal graphs of the normalized strain rate over the generatrix line indicated in Fig.7.6a with the overlaid tensile test curve indicating the nine instants of Figs.7.6a-c. The expression for the computation of the normalized strain rate is detailed in Eq, Tensile test curves comparison and b) tensile test curves for the PM tensile specimens

, Strain profiles to failure over a generatrix line for the a) LFW-AW; b) LFW-AW-PC

.. .. Pm,

, Fractograph of a typical PM tensile specimen showing a) the entire surface; b) the intergranular fracture surface of ? grain; c) dimples at the the intergranular fracture surface of ? grain; d-e) fracture mechanisms at the ? grain boundary, p.247

, Post-mortem observations of the LFW-AW-PC tensile specimen surface showing a) the upper and lower parts of the tensile specimen using respectively using BSE and SE detectors; b) WCZ-TMAZ boundary showing slips bands and secondary cracks

, 10 Fractographs of a LFW-AW-PC cross-weld tensile specimen showing a) the entire fracture surface; b) equiaxed objects with comparable size to the distorted ? grains at the WCZ; elongated dimples with comparable morphology to c) the ? WI in the core of ? grains and to d) the ? WGB colonies at the PM grain boundary -notice the difference in scale between c and d-; e and f) ED fractograph showing elongated dimples, WCZ fine equiaxed distorted ? grains showing the locally oriented slip bands, and d) Slip bands at the WCZ-TMAZ boundary, p.249

, Fractograph of the PHWT-2 tensile specimen; b) elongated fracture feature similar to the ? p WI in the core of PM ? grains ; c-d) SEM fractographs of the PWHT tensile specimen for comparison with e-f) BSE observations of the PM microstructure far from the former WCZ, p.251

, LFW-AW (blue) and PWHT (red) fatigue specimens. (R=0.1), Wöhler curves for the PM (gray)

. Résumé-de-chapitre,

, Une discussion des résultats les plus importants de cette thèse, des conclusions et les perspec

P. .. Conclusions,

. .. , 264 8.2 Tensile test for a Ti17 PM (gray line), a cross-weld tensile specimen of a similar Ti17 LFW joint (black line) and a cross-weld tensile specimen of a dissimilar Ti17-Ti64 LFW joint (red line). Fracture surfaces for both cross-weld tensile specimens highlighting clusters of parallel elongated fracture dimples, Figures 8.1 S-N curves for smooth specimens for all studied configurations. R= 0.1

, Normalized strain rate a) maps and b) spatio-temporal graphs for a similar Ti6242 LFW joint

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