ASTM A193 Grade B8

About ASTM A193 Grade B8

ASTM A193 Grade B8 is a standard material specification for high-tensile, corrosion-resistant austenitic stainless steel fasteners. Manufactured from AISI 304 stainless steel, these fasteners are engineered for extreme environments, such as high-temperature, high-pressure, or cryogenic services.

The primary products under this specification include heavy hex bolts, fully threaded stud bolts, and threaded rods utilized in pressure piping, valves, flanges, and fittings.

Key Technical Specifications

Class Classifications & Mechanical Performance

According to the specification, Grade B8 is split into two primary classes based on heat treatment:

Class 1 (Carbide Solution Treated)

• Process: Fasteners are solution-annealed and water-quenched to guarantee maximum corrosion resistance.

• Tensile Strength: 75 ksi (515 MPa) minimum.

• Yield Strength: 30 ksi (205 MPa) minimum.

• Core Advantage: Exceptional ductility and low magnetic permeability.

Class 2 (Carbide Solution Treated & Strain Hardened)

• Process: Plastically deformed through a strain-hardening process to elevate strength.

• Tensile Strength: Up to 125 ksi (860 MPa) minimum.

• Yield Strength: Up to 100 ksi (690 MPa) minimum.

• Core Advantage: Drastically reduces the potential for thread galling during high-torque assembly.

Core Applications

Because these fasteners reliably resist atmospheric rust and localized chemical attacks, technical resources like Jignesh Steel trace their usage to several key sectors:

• Oil & Gas Processing: Flange connections on high-pressure offshore lines.

• Chemical Vessels: Fastening components inside highly corrosive acid tanks and boilers.

• Marine Engineering: Equipment assembly exposed to rigorous saltwater/chloride conditions.

• Power Generation: High-temperature heat exchangers and steam piping systems.