Strain-hardenability of new strengthened TRIP/TWIP titanium alloys

Y. Danard (1) , Lola Lilensten (1) , F. Sun (1) , P. Vermaut (1) , I. Freiherr von Thüngen , G. Martin (2) , N. Bozzolo (3) , F. Prima (1)

1 IRCP - Institut de Recherche de Chimie Paris
2 SIMaP - Science et Ingénierie des Matériaux et Procédés
3 CEMEF - Centre de Mise en Forme des Matériaux

A new Ti-Cr based alloy has been developed to reach a TWIP (TWinning Induced Plasticity) effect as the main deformation mechanism. This new composition, involving Fe addition, was derived from a classical TRIP/TWIP alloy Ti-8.5Cr-1.5Al (wt%) (TCA). The main objective is to achieve an optimized strength/hardenability combination by limiting the TRIP (TRansformation Induced Plasticity) effect whose critical resolved shear stress lowers the plasticity threshold. This new alloy Ti-7Cr-1Al-xFe (wt%) (TCAF) displays excellent mechanical properties, with an increased yield strength (with respect to TCA alloy), a very high work-hardening rate and an extremely high fracture strength (UTS=1415MPa), while maintaining an excellent ductility (ε=0.38 at fracture). Both mechanical (tensile tests) and microstructural characterization at different scales (EBSD, XRD) have been performed, evidencing a dense network of fine {332}<113> mechanical twins as well as the presence of stress-induced martensite plates at twins intersections, as a secondary mechanism.

Domaines: Matériaux

Y. Danard, Lola Lilensten, F. Sun, P. Vermaut, I. Freiherr von Thüngen, et al.. Strain-hardenability of new strengthened TRIP/TWIP titanium alloys. Titanium 2019-14th World Conference on Titanium (Ti 2019), Oct 2019, Nantes, France. pp.11056, ⟨10.1051/matecconf/202032111056⟩. ⟨hal-04277328⟩