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

Wang Baozhong

doi:10.11648/j.ijmea.20180602.11

Abstract

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.

Highlights

Stainless steel has been widely and deeply concerned since the advent of it which has been the beloved of the material industry
There are many ‘good experiences’ for stainless steel forgings such as the narrow deformation temperature range, the higher deformation resistance, the objective existence of harmful phases such as ferrite and the impossibility of grain size improvement by the phase change heat treatment and so on [4, 5], which are intertwined closely, so that the production of large stainless steel forgings are faced with a severe test, which large and unevenness of grain is the outstanding global problems so far
The global leader of forging suppliers have said that large 316LN stainless steel forgings like the AP1000 main pipe can only be

Summary

Introduction

Stainless steel has been widely and deeply concerned since the advent of it which has been the beloved of the material industry. There are many ‘good experiences’ for stainless steel forgings such as the narrow deformation temperature range, the higher deformation resistance, the objective existence of harmful phases such as ferrite and the impossibility of grain size improvement by the phase change heat treatment and so on [4, 5], which are intertwined closely, so that the production of large stainless steel forgings are faced with a severe test, which large and unevenness of grain is the outstanding global problems so far

Regret of Hot Leg a Manufacturing for AP1000 Main Pipe

Research on the Near Net Shape Forming of Pipe Hollow Forgings

Preproduction of Hollow Forging’s Near Net Shape Forming

Conclusion