Titanium and titanium alloy flat blank machining method

The invention relates to a titanium and titanium alloy flat billet processing method, which comprises the following steps: taking a 1/2 height area of a cylindrical cast ingot as a rolling starting position, directly pressing down by using an upper roller, then carrying out reciprocating rolling in two directions, and rolling in the thickness direction and then in the width direction in the rolling process in a manner that the pressing deformation is 5-20% of the diameter of the cast ingot, the maximum value of the downward pressing amount in the width direction along the 1/2L position is 50% of that in the thickness direction, and the rolling starting temperature is 800-1200 DEG C; the titanium alloy strain rate sensitivity is high, the reduction rate is strictly controlled within the range of 1-10 mm/sec, the roller rotating speed is controlled within 20-40 rpm, the roller diameter is larger than 400 mm, 90-degree turnover rolling is carried out when accumulated rolling deformation in the thickness directio