Design of high strength titanium alloy through finding a critical composition with ultra-fine α phase

Abstract

This study presents the design of a high strength titanium alloy based on the idea that the β titanium alloy with critically stable composition could precipitate ultra-fine α phase. An efficient method was used to find the composition of TC21-xV alloy in which ultra-fine α phase could be obtained. It is found that TC21-5V alloy containing ultra-fine α phase and possessing highest hardness could be obtained after solution treatment in the β single-phase region and subsequent aging. The morphology of primary and secondary α phases can be controlled by changing the solution treatment and aging temperatures. Calculation results of driving force and growth rate of secondary α phase show that the growth rate may be a decisive factor for the final size of secondary α phase after solution and aging treatments in the two-phase region. Finally, when the alloy was solution treated at 820°C and aged at 500°C, the highest strength of 1540 MPa was obtained. The alloy was solution treated at 820°C and aged at 600°C exhibited high strength of 1210 MPa with 11.4% elongation.

Structure and Properties of High-Strength Titanium Alloy Ti-6.5Al-3Mo-2.5V-4Nb-1Cr-1Fe-2.5Zr Welded Joints

“…As in welding of steels and alloys [36][37][38][39][40][41], to achieve the required quality characteristics of welded joints, an integrated approach to research methods is required [42][43][44]. This approach includes a comprehensive consideration of the processes at different stages: alloy fabrication [45][46][47][48][49][50]; study of the processes occurring directly during welding [51][52][53]; studying the influence of the welding thermal cycle and reducing of weld metal alloying degree on the structure and mechanical properties of welded joints [6,8,10,12,20,40]; study of the stress-strain state of welded joints after welding [1,13,15,20,54,55]; taking into account the specifics of manufacturing structures [1,2,4,13,16,[19][20][21][22] and so on.…”