ASTM WK41655

    Revision of A193 / A193M - 12b Standard Specification for Alloy-Steel and Stainless Steel Bolting for High Temperature or High Pressure Service and Other Special Purpose Applications

    (What is a Work Item?)

    Active Standard: A193 / A193M - 14

    Developed by Subcommittee: A01.22 | Committee A01 | Contact Staff Manager



    WK41655

    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

    alloy steel bars; alloy steel bolting; fasteners; hardness; heat treatment ; stainless steel bolting;
    Citing ASTM Standards
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    Work Item Status

    Date Initiated:
    04-11-2013

    Technical Contact:
    James Bell

    Item:
    088

    Ballot:
    A01 (13-03)

    Status:
    Ballot Item Approved as A193/A193M-2014 and Pending Publication