ASTM A193 Grade B8S is a standard material specification for high strength, corrosion resistant Alloy 218 / UNS S21800 / Nitronic 60 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 B8S is a carbide solution treated stainless steel further divided into class 1C and class 1D, both having a minimum tensile requirement of 100 ksi, yield 55 ksi and maximum hardness limit of 271 HBW or 28 HRC. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8S Fasteners.
| Property | Description |
|---|---|
| Class 1C | Carbide Solution Treated |
| Class 1D |
| Element | Austenitic Stainless Steel |
|---|---|
| Alloy 218 / UNS S21800 / Nitronic 60 | |
| CompositionA, % | |
| Carbon | 0.10 max |
| Manganese | 7.00 - 9.00 |
| Phosphorus | 0.060 max |
| Sulfur | 0.030 max |
| Silicon | 3.50 - 4.50 |
| Chromium | 16.00 - 18.00 |
| Nickel | 8.00 - 9.00 |
| Nitrogen | 0.08 - 0.18 |
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 1C & 1D | All Sizes | 95 | 50 | 35 | 55 | 271 HBW or 28 HRC | |
Heat Treatment: Carbide Solution Treated
| Nut Specification | Washer Specification |
|---|---|
| ASTM A194 Grade 8S | ASTM A240 UNS S21800 |
| Commonly Produced B8S 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 |