Effects of Extrusion Parameters on Microstructure and Properties of Gr. 38 Titanium Alloy Pipe

By adopting four extrusion temperature, three extrusion ratio and three extrusion speed, effects of extrusion temperature and extrusion ratio as well as extrusion speed on the properties and microstructure of Gr. 38 titanium alloy were investigated. The results reveal that the extrusion parameters have significant influence on the microstructure of Gr. 38(ATI425) titanium alloy. With increasing in the extrusion temperature and extrusion ratio as well as extrusion speed, volume fraction of α phase is decreased, and primary α phase is recrystallized more fully, which is transformed from the distorted elongated shape gradually into spherical ones. Meanwhile, strength of the alloy is declined slightly with slightly rising of the elongation, which is attributed to more and more deformation thermal and deformation energy stored in the alloy resulting in the dynamic recovery and recrystallization. The optimized extrusion parameters of Gr. 38 titanium alloy are presented as follows: extrusion temperature of 900~930℃, extrusion ratio of 14~18 and extrusion speed of 70~80 mm/s.