Preparation method of ultra-large-diameter titanium alloy thin-wall seamless pipe

The invention discloses a preparation method of an ultra-large-diameter titanium alloy thin-wall seamless pipe, which comprises the following steps: selecting a titanium alloy light rod, and punching along the length direction of the titanium alloy light rod to obtain a pipe blank; performing hot piercing rolling on the tube blank to obtain a cold rolled tube blank; performing multi-pass cold rolling on the cold-rolled tube blank to obtain a machined tube blank, and sequentially performing vacuum heat treatment and machining on the machined tube blank to obtain a semi-finished tube blank; carrying out aging heat treatment and straightening on the semi-finished pipe blank circularly until the straightness precision of the semi-finished pipe blank is smaller than or equal to one thousandth; and machining the semi-finished tube blank subjected to aging heat treatment and straightening to obtain a finished titanium alloy tube. By the adoption of the machining process of drilling, hot piercing rolling, cold rollin