ASTM A193 Grade B8T Class 2 Specification
ASTM A193 Grade B8T Class 2 Specification for high tensile bolts, screws, stud bolts, anchor bolts, threaded rods and other externally threaded fasteners, made from 321 stainless steel.
ASTM A193 Grade B8T Class 2 is a standard material specification for corrosion resistant 321 stainless steel fasteners such as bolts, screws, studs, threaded rods and other externally threaded parts, for use in high tensile, high temperature and special purpose applications such as pressure piping & pressure vessels bolting. Grade B8T is strain hardened and carbide solution treated stainless steel having minimum tensile requirement of 100 ksi, yield 50 ksi and maximum hardness limit of 321 HBW or 35 HRC. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8T Class 2 Fasteners.
Chemical Composition
| Element | Austenitic Stainless Steel |
|---|---|
| AISI 321 / 321H | |
| CompositionA, % | |
| Carbon | 0.08 max |
| Manganese | 2.00 |
| Phosphorus | 0.045 max |
| Sulfur | 0.030 max |
| Silicon | 1.00 max |
| Chromium | 17.00 - 19.00 |
| Nickel | 9.00 - 12.00 |
| Titanium | 5 x Carbon Content - 0.70 |
| Nitrogen | 0.10 max |
AThe intentional addition of Bi, Se, Te, and Pb is not permitted.
Mechanical Properties
| Tensile Class | Diameter, Inch | Tensile Strength, min, ksi |
Yield Strength, min, 0.2% offset, ksi |
Elongation in 4D, min, % |
Reduction of Area, min, % |
Hardness, max |
|---|---|---|---|---|---|---|
Class 2A |
3/4 and under | 125 | 100 | 12 | 35 | 321 HBW or 35 HRC |
| over 3/4 to 1 inclusive | 115 | 80 | 15 | 35 | ||
| over 1 to 1-1/4 inclusive | 105 | 65 | 20 | 35 | ||
| over 1-1/4 to 1-1/2 inclusive | 100 | 50 | 28 | 50 |
Heat Treatment: Carbide Solution Treated and Strain Hardened
A: For diameters 11⁄2 and over, center (core) properties may be lower than indicated by test reports which are based on values determined at 1⁄2 radius.
