Comparison the cooling rate effect on the structure and mechanical properties β- and α+β processed VST5553 alloy

VST5553 is one of the new most interesting and promising high-strength near beta titanium alloys with a combination of high strength and fracture toughness. Biggest number of advances this alloy show at 5 " and more heavy sections semi-finished products cause of a large amount of a metastable β-phase to get  the good hardening during aging.

Competing process on the way of fixing the metastable β-phase it is a breakdown during cooling after solid solution heat treatment. Very important factors are cooling rate and type of β-phase structure. Extremly different states are β- recrystallized and fine-grained β after α + β-deformation.

The β- and α + β-state cooling rate effect on the properties and structure VST5553 alloy comparison was done. It is shown that b-recrystallized structure significantly reduces the stability of  beta-phase, providing a more complete breakdown at lower cooling rates.

The β-annealing conditions significantly lower ductility and observed non-linear relationship with the strength compared