•   0091-22-66157017
  •   info@torqbolt.com
    • Home
    2. ASTM A193 Grade B8 Class 1D

    ASTM A193 Grade B8 Class 1D Bolts

    Carbide Solution Treated 304 Stainless Steel Bolting

    ASTM A193 Grade B8 Class 1D refers to austenitic stainless steel bolting materials produced from AISI 304 stainless steel and subjected to a carbide solution treatment. Similar to Class 1, B8 Class 1D bolts are annealed to provide balanced mechanical properties and superior corrosion resistance. They are extensively used in various industrial sectors, including pressure vessel fabrication and piping systems, where reliable performance in corrosive environments is essential.

    The "D" suffix in Class 1D designates the condition where limited cold straightening of hot-rolled bar stock is permitted after carbide solution treatment. Class 1 prohibits all post-anneal cold work; Class 1D allows the minor cold-straightening operations that are practically unavoidable when producing heavy-section bar stock and longer stud lengths. Mechanical property requirements are identical to Class 1: 75 ksi (515 MPa) minimum tensile, 30 ksi (205 MPa) minimum yield, 30% elongation in 4D, and 223 HBW maximum hardness — meaning Class 1D 304 stainless bolts retain full NACE MR0175 / ISO 15156-3 sour-service eligibility (22 HRC austenitic-stainless ceiling). Class 1D is the typical specification for large-diameter heavy hex structural bolts per ASME B18.2.3.3M and long-pattern stud bolts cut from straightened bar.

    Class 1D nitrogen-bearing variants extend the standard B8 chemistry with measured nitrogen additions that raise strength while preserving full austenitic stability. The mechanical envelope is intermediate between solution-annealed Class 1 (75 ksi) and strain-hardened Class 2; for the Class 1 baseline review the B8 Class 1 reference. When higher strength is required without relying on nitrogen-stabilization, the strain-hardened B8 Class 2 page covers the alternative procurement route. Class 1D bolting is most often supplied as socket-head cap screws or hex bolts; for inch-series socket head dimensions consult the ASME B18.3 socket head cap screw page.

    ASTM A193 Grade B8 Bolts Properties

    ASTM A193 Grade B8 Bolts Chemical Requirements

    Austenitic Steels

    Grade Description and UNS Designation Classes C Mn P S Si Cr Ni
    ASTM A193 Grade B8 304, S30400 1D 0.08 2.00 0.045 0.030 1.00 18.0-20.0 8.0-11.0
    Product Analysis VariationB 0.01 0.04 0.010 0.005 0.05 0.20 0.15

    ASTM A193 Grade B8 Bolts 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 B8 Class 1D All diameters carbide solution treated 75 30 30 50 223 HBW or 96 HRBC

    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 A193M Grade B8 All diameters Class 1D All diameters carbide solution treated 515 205 30 50 223 HBW or 96 HRBC
    Related Specifications
    Surface Treatments
    Certifications
    About Us
    Questions? Contact us.
    Showcase of our Microsites.
    Satisfaction Survey

    survey

    TUVRheinland CRETIFIED

    © TorqBolt P(Ltd) · Built with in INDIA.