Strain-hardenability of new strengthened TRIP/TWIP titanium alloys

• Main Authors: Danard Y., Lilensten L., Sun F., Vermaut P., Freiherr Von Thüngen I., Martin G., Bozzolo N., Prima F.
• Format: Article
• Language: English
• Published: EDP Sciences 2020-01-01
• Series: MATEC Web of Conferences
• Online Access: https://www.matec-conferences.org/articles/matecconf/pdf/2020/17/matecconf_ti2019_11056.pdf

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.