Abstract
Ti-6Al-4V seamless pipe was manufactured by the inclined rolling process to take advantage of its higher productivity than the conventional hot extrusion process. Properties of the rolled Ti-6Al-4V seamless pipe was investigated. Also, the pipes, extruded at alpha+beta phase temperature and beta phase temperature, were compared each other. The inclined rolling process was successfully applied to produce Ti-6Al-4V seamless pipes. The pipes possessed uniform fine accicular microstructure and no surface flaws. The balance between 0.2% proof stress and elongation was optimum in the rolled pipe, followed by the alpha+beta extrude pipe with elongated primary alpha phase, and the beta extrude pipe which consisted of coarse beta grains with accicular structure. Crystallographic texture was weakly formed in the rolled pipe, which was similar to that of rolled plate. Similar, but slightly intense texture was formed in beta extruded pipe. Tensile and fracturing properties were isotropic in the rolled and the beta extruded pipe. On the other hand, intense texture was formed in the alpha + beta extruded pipe. C axis direction of titanium alpha phase was intensely orientated to both the transverse and the longitudinal directions. Tensile and fracturing properties were anisotropic in the alpha+beta extruded pipe, due to the intense texture formation. The degree of anisotropy in the properties was correlated with the ratio of the C axis orientation fraction, regardless their manufacturing processes.
