ASTM A193 Grade B8 Class 2B
ASTM A193 Grade B8 Class 2B is a carbide solution treated and strain hardened 304/304L stainless steel bolting material specification, with higher tensile strength requirement of 95 ksi or 655 MPa and 75 ksi or 515 MPa and maximum hardness of 321 HBW or 35HRC. A193 Gr B8 Class 2B fasteners are used for bolting pipeline flanges and other process equipment intended for high temperature or high-pressure applications.
Class 2B is usually sidelined due to wide acceptance of Class 1 & Class 2, however we do not stop producing them. We can offer all types externally threaded fasteners such as Stud Bolts (Studs), Hex Bolts, Socket Head Cap Screws, Threaded Rods, Heavy Hex Bolts, Hex Cap Screws, Double End Studs, Eye Bolts, U Bolts, Countersunk Screws, Round bars, etc., in A193 Grade B8 Class 2B specification.
Chemical Composition
| Elements | Range | Allowed Variation, % |
| Carbon, Max | 0.08% | + 0.01 |
| Manganese, max | 2.00% | + 0.04 |
| Phosphorus, max | 0.045% | + 0.010 |
| Sulfur, max | 0.030% | + 0.005 |
| Silicon, max | 1.00% | + 0.05 |
| Chromium | 18.00 – 20.00% | +/- 0.20 |
| Nickel | 8.00 – 11.00% | +/- 0.15 |
Heat Treatment
| Class | Heat Treatment Procedure |
| Class 2B | Carbide Solution Treatment & Strain Hardened |
Mechanical Properties
Find typical requirement for ASTM A193 Grade B8 Mechanical Properties. Tensile, yield strength and hardness requirement of finished products manufactured to ASTM A193 Grade B8 specification must comply with below requirement.
| Mechanical Requirements, Inch Products | |||||||
|---|---|---|---|---|---|---|---|
| Class | Diameter | Tensile Strength, min, ksi | Yield Strength, min, ksi | Elongation in 4D min, % | Reduction of Area, min, % | Hardness, max | |
| 2B | 2 and under | 95 | 75 | 25 | 40 | 321 HBW | 35 HRC |
| Over 2 to 2-1/2, incl. | 90 | 65 | 30 | 40 | |||
| Over 2-1/2 to 3, incl. | 80 | 55 | 30 | 40 | |||
| Mechanical Requirements, Metric Products | |||||||
|---|---|---|---|---|---|---|---|
| Class | Diameter | Tensile Strength, min, ksi | Yield Strength, min, ksi | Elongation in 4D min, % | Reduction of Area, min, % | Hardness, max | |
| 2B | M48 and under | 655 | 515 | 25 | 40 | 321 HBW | 35 HRC |
| Over M48 to M64, incl. | 620 | 450 | 30 | 40 | |||
| Over M64 to M72, incl. | 550 | 380 | 30 | 40 | |||
ASTM A193 Grade B8 Bolt Markings
| Class | Marking |
|---|---|
| Class 2B | "BPF" Manufacturer's Logo & "B9" Grade Marking |