Effect of boron addition on recrystallization behavior of commercially pure titanium subjected to hot compression

R.A. Gaisin1, V. Imayev, R. Imayev, E. Gaisina
1Institute for metals superplasticity problems of RAS, ul. Khalturina 39, 450001, Ufa, Russia
Abstract
In the present work comparative investigation of recrystallization behavior of cast commercially pure titanium VT1-0 modified by boron and free of boron as well as of CP titanium VT1-0 in wrought condition has been performed after hot compression. Boron additions during the melting process in an amount of 0,2 wt.% lead to formation of uniformly distributed TiB-whiskers, which provided significant refinement of as-cast structure. At room temperature ductility of cast boron-modified alloy was higher than that of cast CP titanium. During hot compression mechanical behaviors of cast boron-modified alloy and wrought CP titanium were similar and considerably differed from the mechanical behavior of cast CP titanium. Recrystallization behavior was studied after hot compression at T=900, 800, 700 and 600C using optical microscopy and EBSD analysis. It was revealed that the boron addition promoted more uniform strain development and accelerated recrystallization during hot compression in the cast CP titanium modified by boron as compared with the CP titanium free of boron. Similar fine-grained structure formed during hot working of cast boron-modified alloy and wrought VT1-0.The most effective dynamic recrystallization of investigated alloys occurred during deformation in the (+β)-phase field (900C). Trace additions of boron in an amount of ~0,1 wt.% can be recommended for wrought titanium alloys to refine as-cast microstructure and facilitate obtaining of uniform fine-grained structure during hot working.
Accepted: 28 May 2015
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