The invention discloses a
forging method of a lower sealing head
forge piece of a one-
mega kilowatt nuclear-
power reactor pressure vessel. In the method, a double-vacuum steel
ingot made of 16MND5 with a weight of 103 tons is forged by using a
hydraulic press of 12,000 tons, wherein the
forging process sequentially comprises the following steps of: drawing: heating the double-vacuum steel
ingot to 1,220+ / -10 DEG C, and changing a length of 2,625mm into 4,600mm; gas
cutting blanking: removing a section of the bottom end of the
forge piece to change the length of 4,600mm into 3,450mm, wherein the bottom of the double-vacuum steel
ingot is guaranteed to be sufficiently
cut off; upsetting: raising the temperature to 1,240+ / -10 DEG C and changing the length of 3,450mm into 290mm; rough
machining: roughly
machining the
forge piece blank into a cake shape, wherein the
diameter of the cake is 5,000mm, and the thickness is 220mm; and
stamping and forming: heating the forge piece to 1,000+ / -10 DEG C and putting the forge piece on a special die for
stamping and forming until the
forging ratio reaches 1.2, and the forge piece forms a spherical crown shape. The invention can ensure that the forged lower sealing forge piece has the advantages of
dense material, uniform component, reasonable
metal streamline distribution and stable property.