EFFECT OF THERMOMECHANICAL TREATMENT CONDITIONS ON MECHANICAL-PROPERTIES OF TI-10V-2FE-3AL ALLOYS

We examined near β type Ti-10V-2Fe-3Al alloys applied to newly proposed thermomechanical treatment. Tensile tests, Charpy impact tests and dynamic fracture toughness tests were carried out on these treated specimens in order to compare their mechanical properties and toughness with those of typical STA treated (1 033 K, 1 h, WQ + 783 K, 8 h, AC) specimens. Alloys conducted with new thermomechanical treatment of 973 K, 1 h, WQ + 75%C.R + 1 033 K, 5 s, WQ + 783 K, 8 h, AC exhibited greater strength and toughness compared with typical STA treated alloys. Toughness of the former, in particular, was considerably greater than that of the latter. Dynamic fracture toughness and dynamic tearing modulus of thermomechanical treated alloys increased considerably with increasing solution treatment temperature after cold rolling of 75% compared with those of typical STA treated alloys. This increase in toughness was considered to be caused by micro cracking near the crack tip, tortuosity of main crack and formation of secondary cracks. Eventually, newly proposed thermomechanical treatment in this study was found to be effective for improving the toughness of Ti-10V-2Fe-3Al alloys.