New manufacturing techniques of large forged shell rings for pressure vessels

Comparison of mechanical and metallurgical properties of hollow and solid forged products

“…The ingots used for solid and hollow forging should possess excellent metallurgical and workability characteristics [6,7] and so they are often produced by the electro slag remelting (ESR) process [8]. ESR leads to significant reductions in the sulfur content and to some reductions in the phosphorus, silicon and niobium contents [9].…”

60th Anniversary of electricity production from light water reactors: Historical review of the contribution of materials science to the safety of the pressure vessel

“…After this technical turn, constant progress in casting and forging operations was required to manufacture larger and larger RPVs. For instance, ingots of about 600 tons are now necessary to make ring shells for the Hitachi-GE ABWR (Advanced Boiling Water Reactor) or the AREVA EPR, compared to only about 200 tons for typical 900 -1300 MW PWRs [12]. To work on such large ingots, while improving their homogeneity and reducing steel impurity levels, manufacturers had to equip themselves with advanced casting technologies, e.g., Vacuum Induction Melting (VIM) and…”

“…In the meantime, manufacturers also developed codes to optimize casting and forging operations from computer simulations. Among the first applications, was the development of the "hollow ingot" technology for RPV in the 1980s [12], which allows obtaining a "clean" (i.e., without any significant segregation zones) wall inner side.…”