STP1042

    The Effects of Phosphorus and Boron on the Behavior of a Titanium Stabilized Austenitic Stainless Steel Developed for Fast Reactor Service

    Published: Jan 1989


      Format Pages Price  
    PDF Version (660K) 26 $25   ADD TO CART
    Complete Source PDF (6.4M) 26 $70   ADD TO CART


    Abstract

    Austenitic stainless steels are used for core component materials in liquid metal cooled reactors (LMRs). To extend the lifetime of LMR fuel assemblies, considerable effort was expended by the U.S. breeder materials program to find ways to minimize radiation induced dimensional changes (swelling and creep) and to maximize the creep rupture strength. After various elements were shown to affect strongly swelling and creep behavior, compositional modifications to a commercial grade austenitic stainless steel (American Iron and Steel Institute 316 UNS S31600) produced an alloy with significant improvement in swelling resistance over the standard 300 series alloys. Changes were primarily in the concentrations of chromium, nickel, silicon, and titanium. ASTM Specification for Austenitic Stainless Steel Tubing for Breeder Reactor Core Components (A 771-83) was approved in 1983 for the new alloy, designated UNS S38660.

    Substantial improvement can be produced in the creep rupture behavior of this alloy. Elements such as phosphorus and boron, typically present in trace quantities, have a significant influence on the creep strength of austenitic stainless steels. Several heats of alloy S38660 were made that systematically varied the phosphorus and boron contents. Uniaxial creep tests were conducted at 704°C (1300°F) to evaluate the effects of these elements on the creep rate and the rupture life. The results of these tests were used to guide the production of reactor grade fuel pin cladding for further evaluations. Pressurized tube specimens were tested in the laboratory and also in a fast reactor. Results of these investigations have shown that the elements phosphorus and boron, present in minute but controlled amounts, increase both the in-reactor and ex-reactor rupture life and reduce both in-reactor swelling and creep rate. Microstructural evaluations were also conducted to help ascertain the mechanisms by which the improved properties were obtained.

    Keywords:

    phosphorus, boron, austenitic stainless steel, titanium stabilized stainless steel, swelling, creep, stress rupture, D9, D9I


    Author Information:

    Hamilton, ML
    Senior research scientist and staff scientist, Pacific Northwest Laboratory, Richland, WA

    Johnson, GD
    Manager of materials engineering and manager of irradiation development, Westinghouse Hanford Company, Richland, Washington,

    Puigh, RJ
    Manager of materials engineering and manager of irradiation development, Westinghouse Hanford Company, Richland, Washington,

    Garner, FA
    Senior research scientist and staff scientist, Pacific Northwest Laboratory, Richland, WA

    Maziasz, PJ
    Research staff member, Oak Ridge National Laboratory, Oak Ridge, TN

    Yang, WJS
    Knolls Atomic Power Laboratory, Schenectady, NY

    Abraham, N
    Department of Energy, Washington, DC


    Paper ID: STP24576S

    Committee/Subcommittee: A01.14

    DOI: 10.1520/STP24576S


    CrossRef ASTM International is a member of CrossRef.