Low-temperature-resistant high-strength high-toughness steel forge piece and forging method thereof

The invention provides a low-temperature-resistant high-strength high-toughness steel forge piece and a forging method thereof. The forging method comprises the steps of drawing, homogenization treatment and forging forming. According to drawing, drawings of a plurality of parts are subjected to simulation bushing combination to form a drawing of an integral part, and follow-up forging production is conducted according to the size in the drawing of the integral part. The forging comprises four upsetting and four drawing, in the first three times of treatment, upsetting is performed until the height of the steel ingot is half of that of the steel ingot, then the steel ingot is drawn until the height-diameter ratio is 2.3-2.7, and the steel ingot is returned to a furnace and is subjected to heat preservation at 1140 DEG C for 2-4 hours; and in the last treatment, upsetting to half of the height of the steel ingot after discharging, drawing to form a rough blank, reserving a certain deformation amount (50-60%),