Development of Austenitic Stainless Steel Cold-drawn Rods for Nuclear Power Plant Reactor Internals

Abstract

Austenitic stainless steel for nuclear power plant reactor internals is extremely strict in terms of purity， grain size， corrosion resistance and mechanical properties， and stable quality materials are crucial to the safe operation of nuclear power plants. By setting a reasonable chemical composition（mass fraction） target value for 316 stainless steel， namely w［C］0. 045%，w［N］0. 06%，w［Cr］17. 00%，w［Mo］2. 50%，w［Ni］12. 50，w［Mn］1. 80%； Three dimen⁃ sional pre-melting and remelting smelting is used to improve the purity of molten steel， and low melting speed is set to re⁃ duce smelting segregation. Combine forging and rolling； control the consolidation insulation time according to material specifications and accurately control the cold drawing deformation at 2 mm. The austenitic stainless steel SA-479 316（N- 60-6） cold-drawn bar for reactor internals has been successfully developed. Its non-metallic inclusions A， B， C and D are all ≤1. 0 grade， grain size reaches grade 5， intergranular corrosion qualified， room temperature yield strength 479-545 MPa， high temperature tensile strength 515-575 MPa at 350 ℃， meeting the requirements for the use of cold drawn bars for in-stack components.

Keywords

• key words：reactor internals； austenitic stainless steel； cold drawn bars； mechanical property