ASTM A193 Grade B8M Class 2
ASTM A193 Grade B8M Class 2 is a carbide solution treated and strain hardened 316/316L stainless steel bolting material specification, with higher tensile strength requirement of 125 ksi or 860 MPa and 100 ksi or 690 MPa and maximum hardness of 321 HBW or 35HRC. B8M Class 2 fasteners have higher tensile as compared to B8M Class 1 fasteners and are used for high strength bolting intended for high temperature or high-pressure applications.
Boltport is a manufacturer and supplier of A193 Grade B8M Class 2 Bolts and other fasteners such as Stud Bolts (Studs), Hex Bolts, Socket Head Cap Screws, Threaded Rods, Heavy Hex Bolts, Hex Cap Screws, Double End Studs, Anchor Bolts, U Bolts, Countersunk Screws, Round bars, etc.,
See below for more information on ASTM A193 Grade B8M chemical composition, Class 2 heat treatment, and mechanical properties such as tensile strength, yield strength, hardness requirement, product marking, applicable product standards, etc., You can visit class-1-vs-class-2 to check out difference between Class 1 & Class 2 bolting material.
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 |
| Molybdenum | 2.00 – 3.00% | +/- 0.10 |
Heat Treatment
| Class | Heat Treatment Procedure |
| Class 2 | Carbide Solution Treatment & Strain Hardened |
Mechanical Properties
| Mechanical Requirements, Inch Products | |||||||
|---|---|---|---|---|---|---|---|
| Class | Diameter | Tensile Strength, min, ksi | Yield Strength, min, ksi | Elongation in 4D min, % | Reduction of Area, min, % | Hardness, max | |
| 2 | 3/4 and under | 110 | 95 | 15 | 45 | 321 HBW | 35 HRC |
| Over ¾ to 1, incl. | 100 | 80 | 20 | 45 | |||
| Over 1 to 1-1/4, incl. | 95 | 65 | 25 | 45 | |||
| Over 1-1/4 to 1-1/2, incl. | 90 | 50 | 30 | 45 | |||
| Mechanical Requirements, Metric Products | |||||||
|---|---|---|---|---|---|---|---|
| Class | Diameter | Tensile Strength, min, ksi | Yield Strength, min, ksi | Elongation in 4D min, % | Reduction of Area, min, % | Hardness, max | |
| 2 | M20 and under | 760 | 655 | 15 | 45 | 321 HBW | 35 HRC |
| Over M20 to M24, incl. | 690 | 550 | 20 | 45 | |||
| Over M24 to M30, incl. | 655 | 450 | 25 | 45 | |||
| Over M30 to M36, incl. | 620 | 345 | 30 | 45 | |||
ASTM A193 Grade B8M Bolt Markings
| Class | Marking |
|---|---|
| Class 2 | "BPF" Manufacturer's Logo & "B8MSH" Grade Marking |
