ASTM A193 Grade B8M2 is a standard material specification for high strength, corrosion resistant 316 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 B8M2 is a carbide solution treated & strain hardened stainless steel classified under class 2B and both having a minimum tensile requirement of 80 ksi, yield 55 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 B8M2 Fasteners.
| Element | Austenitic Stainless Steel |
|---|---|
| AISI 316 / 316L | |
| CompositionA, % | |
| Carbon | 0.08 max |
| Manganese | 2.00 max |
| Phosphorus | 0.045 max |
| Sulfur | 0.030 max |
| Silicon | 1.00 max |
| Chromium | 16.00 - 18.00 |
| Nickel | 10.00 - 14.00 |
| Molybdenum | 2.00 - 3.00 |
AThe intentional addition of Bi, Se, Te, and Pb is not permitted.
| 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 2BA |
2 and under | 95 | 75 | 25 | 40 | 321 HBW or 35 HRC |
|
| over 2 to 2-1/2 inclusive | 90 | 65 | 30 | 40 | |||
| over 2-1/2 to 3 inclusive | 80 | 55 | 30 | 40 | |||
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.
| Nut Specification | Washer Specification |
|---|---|
| ASTM A194 Grade 8M | ASTM A240 TP316 |
| Commonly Produced B8M2 Fasteners | ||||
|---|---|---|---|---|
| Hex Bolts | Heavy Hex Bolts | Stud Bolts | Threaded Rods | Anchor Bolts |
| Eye Bolts | Socket Head Cap Screws | Countersunk Screws | U Bolts | Square Head Bolts |