Deformation behavior and texture development in beta Ti-V alloys
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Technology, Atlanta, Ga. 30332. Manuscript submitted June 4, 1973. METALLURGICAL TRANSACTIONS
Two sets of s a m p l e s were r o l l e d at room t e m p e r a t u r e in i n c r e m e n t s of 10 pct reduction in thickness p e r p a s s . The {110} and {200} pole figures were d e t e r m i n e d for each composition after 50 and 90 pct reduction on one s e t , and a f t e r 90 pct reduction for the other. The s a m p l e s were m e c h a n i c a l l y polished through 600 g r i t SiC p a p e r s , and then c h e m i c a l l y polished p r i o r to the pole figure m e a s u r e m e n t s . The data was c o r r e c t e d for background and defocusing conditions and plotted with a CAL COMP-plotter. The pole figures a r e not n o r m a l i z e d to a multiple of random intensity but a r e plotted in a r b i t r a r y units. Tensile s a m p l e s were cut from the c o l d - r o l l e d sheet of one s e t a f t e r 90 pct reduction in thickness. Samples were machined p a r a l l e l to and at 45 deg to the r o l l i n g d i r e c t i o n . Some of the sheet was r e c r y s t a l l i z e d for two hours at 850~ and the {110} and {200} pole figures were d e t e r m i n e d . Tensile s a m p l e s were cut f r o m the r e c r y s t a l l i z e d sheet p a r a l l e l to, and at 45 deg to the r o l l ing d i r e c t i o n . Diamond p y r a m i d h a r d n e s s m e a s u r e ments were made on each sample after e v e r y t r e a t ment. The t e n s i l e t e s t s were made on an Instron t e s t ing machine at a s t r a i n r a t e of 0.04 p e r min. All s p e c imens f r o m the sheet m a t e r i a l were pulled to f r a c t u r e . II. R E S U L T S Significant changes in the deformation characteristics were observed optically when the vanadium content was v a r i e d from 20 to 40 pct (Fig. l(a) through (d)). Twinning was the p r e d o m i n a t e mode of deformation in the 20 pct V s a m p l e (Fig. l(a))." The twins v a r i e d in thickness f r o m a few a n g s t r o m s to 20 m i c r o n s , so they were e a s i l y v i s i b l e optically. The twins were found to be of the type {112}(111) by a combination of s e l e c t e d a r e a diffraction and t r a c e a n a l y s i s . This r e s u l t is in a g r e e m e n t with that found p r e v i o u s l y by Patton and W i l l i a m s 2 on Ti-V alloys. Higher magnifications of the twins by TEM show them to be i n t e r n a l l y twinned or deformed by p l a n a r slip (Figs. 2(a) and 2(b)). The deformation mode changed from c o a r s e twinning to fine p l a n a r slip as the vanadium content was inc r e a s e d . Fig. 3, which is an e l e c t r o n m i c r o g r a p h of the 28 pct V alloy, is c h a r a c t e r i s t i c of the behavior. On an optical scale the slip bands a r e frequently seen to be curved or wavy due to the activation of multiple slip, (Fig. l(c)). Selected a r e a diffraction and t r a c e a n a l y s i s indicated that both {112} and {110} slip planes were active. Although twins were observed, they were much finer and l e s s frequent than in the 20
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