Research on the Near Net Shape Hollow Forging Technology for CAP 1400 Main Pipe

It has been widely focused because of its complex integral-structure and strict technical requirement since AP1000 main pipe appeared, which is made by 316LN stainless steel. After ten years of effort and exploring, excellent forging suppliers from all over the world agree that 316LN heavy forgings including AP1000 only can be formed by relatively simple solid forging technology though the grain size cannot meet the initial design requirement of ASTM level-4. The design concept of CAP1400 main pipe is the same as AP1000, in which the straight part, curving part and two supper-long asymmetrical nozzles should be an integrated structure manufactured by 316LN steel. But due to larger dimension and higher requirement for technology, the manufacturing of CAP1400 is more difficult. In order to realize the near net shape manufacturing of CAP1400 main pipe, we invent a green manufacturing technology with highly asymmetrical nozzle for stainless steel main pipe hollow forgings, We have successfully manufactured a stainless hollow forgings using a 78t ESR ingot with nozzle height of 400mm, wall thickness of 160mm, total length of 9000mm, and ASTM level 4-6 of grain size for each part.