ASTM A193 Grade B8C Class 2 is a standard material specification for corrosion resistant grade 347 stainless steel fasteners such as hex bolts, screws, stud bolts, anchor bolts, 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 B8C Class 2 is a carbide solution treated and strain hardened 347 stainless steel with minimum tensile requirement of 100 ksi, yield of 50 ksi & maximum hardness requirement of 321 HBW or 35 HRC. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8C Class 2 Fasteners.
| Element | Austenitic Stainless Steel |
|---|---|
| AISI 347 | |
| 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 |
| Columbium + tantalum | 10 x Carbon Content - 1.10 |
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 2 |
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 11⁄2, inclusive | 100 | 50 | 28 | 45 |
Heat Treatment: Carbide Solution Treated and Strain Hardened
| Nut Specification | Washer Specification |
|---|---|
| ASTM A194 Grade 8C | ASTM A240 TP347 |
| Commonly Produced B8C Class 1 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 |