ASTM WK41668

    Work Item: ASTM WK41668 - Revision of A479 / A479M - 12 Standard Specification for Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels

    (What is a Work Item?)

    Active Standard: A479 / A479M - 13b

    Developed by Subcommittee: A01.17 | Committee A01 | Contact Staff Manager



    1. Rationale

    ASTM A240 and A249 have a nitrogen range of .18/.25 for grade UNS S31254. This specification has a range for the same grade of .18/.22. The benefits of nitrogen in 6 Moly grades is well understood. Higher nitrogen is beneficial to corrosion resistance and increases strength levels. Further, in this particular grade, the higher nitrogen range allows a melt code to be designed so that it solidifies in the totally austenitic mode. Solidifying in the totally austenitic mode eliminates formation of delta ferrite during casting and solidification. Delta ferrite can later transform into deleterious phases like sigma that are detrimental to corrosion resistance and impact strength. Allowing higher nitrogen levels is beneficial to the material. Hence, we propose to raise the nitrogen limit in this specification to .25 to match ASTM A240 and A249.


    Keywords

    austenitic stainless steel; austenitic-ferritic duplex stainless steel; ferritic stainless steel; martensitic stainless steel; pressure-containing parts; pressure vessel service; stainless steel bars; stainless steel shapes; temperature service applications—high;
    Citing ASTM Standards
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    Work Item Status

    Date Initiated:
    04-11-2013

    Technical Contact:
    James Bell

    Item:
    017

    Ballot:
    A01 (13-04)

    Status:
    Ballot Item Approved as A479/A479M-2013B and Pending Publication