ASTM A193 Grade B8N Class 1B is a standard material specification for high strength 304N 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 B8N Class 1B is a carbide solution treated 304N stainless steel having minimum tensile requirement of 80 ksi, yield 30 ksi and maximum hardness limit of 223 HBW or 96 HRB. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8N Class 1B Fasteners.
| Element | Austenitic Stainless Steel |
|---|---|
| AISI 304N / UNS S30451 | |
| CompositionA, % | |
| Carbon | 0.08 max |
| Manganese | 2.00 |
| Phosphorus | 0.045 max |
| Sulfur | 0.030 max |
| Silicon | 1.00 max |
| Chromium | 18.00 - 20.00 |
| Nickel | 8.00 - 11.00 |
| Molybdenum | 0.10 - 0.16 |
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, maxA |
|
|---|---|---|---|---|---|---|---|
| Class 1B | All Sizes | 80 | 35 | 30 | 40 | 223 HBW or 96 HRB | |
Heat Treatment: Carbide Solution Treated
A: For sizes 3⁄4 in. in diameter and smaller, a maximum hardness of 241 HBW (100 HRB) is permitted.
| Nut Specification | Washer Specification |
|---|---|
| ASTM A194 Grade 8N | ASTM A240 UNS S30451 |
| Commonly Produced B8N Class 1B 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 |