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    2. ASTM A193/A193M Grade B8TA Class 1A

    ASTM A193/A193M Grade B8TA Class 1A Stud Bolts – UNS S32100

    Strain hardened, titanium-stabilized 321 stainless steel stud bolts for high-strength bolting in elevated temperature and sensitization-prone service environments.

    ASTM A193/A193M Grade B8TA Class 1A Stud Bolts are manufactured from UNS S32100 Type 321 titanium-stabilized austenitic stainless steel and are cold worked to achieve the enhanced mechanical strength that distinguishes Class 1A from the solution annealed Class 1 condition, with testing performed on the finished fastener to confirm compliance with ASTM A193 requirements. Titanium stabilization protects the material against sensitization by forming preferential titanium carbides that prevent the precipitation of chromium carbides at grain boundaries when the steel is exposed to the sensitization temperature range during service or fabrication. Combined with the strength gains from strain hardening, Grade B8TA Class 1A stud bolts offer a superior combination of resistance to intergranular corrosion, elevated temperature mechanical performance, and load-carrying capacity compared to solution annealed equivalents. These fasteners are well suited for use in aerospace exhaust systems, jet engine components, industrial furnaces, and high-temperature pressure vessels where the stabilized alloy chemistry and enhanced strength are both simultaneously required.

    ASTM A193/A193M Grade B8TA Class 1A Chemical Composition - Austenitic Steels

    Grade Description and UNS Designatio Classes C Mn P S Si Cr Ni Ti N
    ASTM A193 Grade B8TA 321, S32100 1, 1A, 2 0.08 2.00 0.045 0.030 1.00 17.0-19.0 9.0-12.0 5 × (C + N) to 0.70 0.10
    Product Analysis VariationB 0.01 0.04 0.010 0.005 0.05 0.20 0.15 0.05 under . . .
    • (A) Values are maximums unless a range or a minimum is indicated. Where ellipses appear in this table, there is no requirement and the element need not be determined or reported. The intentional addition of Bi, Se, Te, and Pb is not permitted.
    • (B) Product Analysis-Individual determinations sometimes vary from the specified limits as shown in the tables. The several determinations of any individual element in a heat may not vary both above and below the specified range. Product variation limits are over for maximums, over or under for ranges, and under for minimums, unless otherwise indicated.
    • (C) Typical steel compositions used for this grade include 4140, 4142, 4145, 4140H, 4142H, and 4145H.
    • (D) For bar sizes over 31/2 in. [90 mm], inclusive, the carbon content may be 0.50% max. For the B7M grade, a minimum carbon of 0.28% is permitted, provided that the required tensile properties are met in the section sizes involved, the use of AISI 4130 or 4130H is allowed.
    • (E) Total of soluble and insoluble.
    • (F) Columbium and Niobium are alternate names for element 41 in the Periodic Table of the Elements.

    ASTM A193/A193M Grade B8TA Class 1A Mechanical Requirements - Austenitic Steels (Inch)

    Grade Diameter,
    in.     		Heat TreatmentB Tensile Strength,
    min, ksi     		Yield Strength, min,
    0.2 % offset, ks     		Elongation in 4 D,min Reduction of Area, min Hardness,
    max
    ASTM A193 Grade B8TA Class 1A All diameters carbide solution treated in the finished condition 75 30 30 50 192 HBW or 90 HRB
    • (A) To meet the tensile requirements, the Brinell hardness shall be over 200 HBW (93 HRB).
    • (B) Class 1 is solution treated. Class 1A is solution treated in the finished condition for corrosion resistance; heat treatment is critical due to physical property requirement. Class 2 is solution treated and strain hardened. Austenitic steels in the strain-hardened condition may not show uniform properties throughout the section particularly in sizes over 3/4 in. in diameter.
    • (C) For sizes3/4 in. in diameter and smaller, a maximum hardness of 241 HBW (100 HRB) is permitted.
    • (D) For diameters 11/2 and over, center (core) properties may be lower than indicated by test reports which are based on values determined at1/2 radius.

    ASTM A193/A193M Grade B8TA Class 1A Mechanical Requirements - Austenitic Steels (Metric)

    Grade Class ,
    mm     		Diameter Heat TreatmentB Tensile Strength,
    min,MPa     		Yield Strength, min,
    0.2 % offset, MPa     		Elongation in 4 D,min % Reduction of Area, min % Hardness,
    max
    ASTM A193 Grade B8TA Class 1A All diameters carbide solution treated in the finished condition 515 205 30 50 192 HBW or 90 HRB
    • (A) To meet the tensile requirements, the Brinell hardness shall be over 200 HBW (93 HRB).
    • (B) Class 1 is solution treated. Class 1A is solution treated in the finished condition for corrosion resistance; heat treatment is critical due to physical property requirement. Class 2 is solution treated and strain hardened. Austenitic steels in the strain-hardened condition may not show uniform properties throughout the section particularly in sizes over M20 mm in diameter.
    • (C) For sizes M20 mm in diameter and smaller, a maximum hardness of 241 HBW (100 HRB) is permitted.
    • (D) For diameters M38 and over, center (core) properties may be lower than indicated by test reports which are based on values determined at1/2 radius.

    ASTM A193/A193M Grade B8TA Class 1A Bolting Components Marking - Austenitic Steels

    Grade Class Grade Symbol
    ASTM A193 Grade B8TA Class 1A TB B8J or TB B8TA

    Related ASTM A193 Grades & ASME Companion Dimensions

    Frequently Asked Questions

    What is ASTM A193 Grade B8TA Class 1A?
    ASTM A193 Grade B8TA Class 1A is a bolting material covering 321 SS Ti-stabilized for high-temp (UNS S32100). Class 1A — solution treated in finished condition for corrosion resistance. Used in high-temperature, high-pressure flange, pressure-vessel and heat-exchanger bolting service per ASTM A193/A193M.
    What is the UNS designation for ASTM A193 Grade B8TA Class 1A?
    The UNS designation for ASTM A193 Grade B8TA Class 1A is UNS S32100. This corresponds to 321 SS Ti-stabilized for high-temp. The UNS code is universal across ASTM, ASME (SA-193), PED 2014/68/EU and NORSOK material specifications. The 'Class 1A' designator denotes the heat treatment condition under ASTM A193 Table 3.
    What is the difference between B8T (321 SS) and B8 (304 SS) (Class 1A)?
    B8T is 321 stainless — Ti-stabilized 304. The titanium addition (Ti ≥ 5×C, max 0.70%) prevents chromium-carbide precipitation in the 425–815 °C sensitization range, providing better high-temperature inter-granular corrosion resistance than plain B8. Specific to ASTM A193 Grade B8TA Class 1A: Class 1A — solution treated in finished condition for corrosion resistance.
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