Full Text Available The alloy (Ti-6.5AL-3.3 Mo-1.6Zr-O.3Si is a Soviet composition designated VT-9. Excellent superplastic characteristics found by us in this alloy prompted us to explore the possibility of use of Si-free VT-9 in sheet form for superplastic forming. An optimum thermomechanical processing produced a microstructure that resulted in an elongation of 1700 per cent at a fairly high deformation rate (2 X 10-3 set-1. Thus, the same aeroengine alloy (VT-9 can be used for superplastically formed airframe parts in the Si-free condition. The present study also shows that for making the forming process commercially viable, deformation temperature could be lowered by temporarily alloying with hydrogen in a particular concentration range (0.1 to 0.2 wt per cent.
Alexander I. Khaimovich
Full Text Available The present paper presents a method of analysis of titanium alloys plastic properties under severe deformation conditions during milling with registration of the cutting force components Fx, Fy, Fz in real time using a special stand. The obtained constitutive relations in the form the Johnson-Cook law for stresses and dependence for a friction coefficient describing the titanium alloy VT9 plastic properties under simulate operating conditions.