Manufacturing process of large spindle single vacuum steel ingot forge piece

The invention discloses a manufacturing process of a large spindle single vacuum steel ingot forge piece. The manufacturing process comprises a single vacuum steel ingot smelting procedure, a forging procedure and a heat treatment procedure. In the single vacuum steel ingot smelting procedure, steel ingot material components are internally controlled. The forging procedure comprises four-heating-number forging. In first-heating-number forging, an upper ingot body is subjected to handle pressing, circle pressing and bottom staggering. In second-heating-number forging, the forge piece is subjected to upsetting and circle pressing. In third-heating-number forging, the forge piece is subjected to upsetting and circle pressing again. In fourth-heating-number forging, the forge piece is subjected to drawing-out, marking, step forging and correction to the size required by the forge piece. The heat treatment procedure comprises temperature equalizing treatment, quenching treatment and high-temperature tempering trea