ASTM A193 Grade B8P Class 1 (305 Stainless)
305 stainless bolting — the low-work-hardening 18-8 for cold-headed and deep-formed fasteners that must stay non-magnetic.
What A193 B8P Class 1 is.
ASTM A193 Grade B8P is bolting in Type 305, an 18-8 stainless with 11 to 13 percent nickel. The extra nickel makes the austenite more stable, so the alloy work-hardens far less than 304 during cold heading or thread rolling and stays essentially non-magnetic afterwards.
Mechanically it is treated like B8: Class 1 solution treated at 75 ksi, Class 2 strain hardened to 125 ksi in small sizes. We supply it where a specification calls for 305 or where magnetic permeability after forming matters.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | — | 0.12 |
| Manganese | Mn | — | 2.00 |
| Phosphorus | P | — | 0.045 |
| Sulfur | S | — | 0.030 |
| Silicon | Si | — | 1.00 |
| Chromium | Cr | 17.0 | 19.0 |
| Nickel | Ni | 11.0 | 13.0 |
Values per ASTM A193/A193M-24, Tables 1 and 2 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
Mechanical properties.
| Nominal diameter (in.) | Tensile strength, min (ksi) | Yield strength 0.2% offset, min (ksi) | Elongation in 4D, min (%) | Reduction of area, min (%) | Hardness, max |
|---|---|---|---|---|---|
| Class 1 — all diameters | 75 | 30 | 30 | 50 | 223 HBW / 96 HRB |
| Class 1A (B8PA) — all diameters | 75 | 30 | 30 | 50 | 192 HBW / 90 HRB |
Values per ASTM A193/A193M-24, Tables 1 and 2 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Class 1 sizes ¾ in. and smaller may be 241 HBW / 100 HRB. Strain-hardened Class 2 properties are on the B8P Class 2 page.
Specifications that apply.
How A193 B8P Class 1 ships from Houston.
- Full-thread studs and stud bolts
- Hex and heavy hex bolts
- Socket head cap screws
- Hex nuts in the same alloy
- Threaded rod
- Machined components from certified bar
A193 B8P Class 1 fasteners we make.
Every item is manufactured to your drawing or standard in A193 B8P Class 1, imperial or metric, with an EN 10204 3.1 certificate.
What is ASTM A193 B8P?
Type 305 is 304 with about three percentage points more nickel. That shift keeps the structure fully austenitic through heavy cold work, so 305 does not pick up the martensite that makes formed 304 parts slightly magnetic and harder to machine. A193 lists B8P alongside B8 with the same Class 1 and Class 2 requirements and the same companion nut family (Grade 8P). Corrosion resistance is equivalent to 304.
Testing, certification and marking
- Tensile and hardness tested per lot on the finished product
- Grade or alloy marking B8P and manufacturer's identification on every piece
- EN 10204 3.1 material test report with heat number and chemistry; 3.2 witness available
ASTM A193 Grade B8P Class 2 (305 Strain Hardened)
High-nickel 305 bolting cold worked to 125 ksi tensile in ¾ in. and under — strength with the lowest magnetic permeability of the strain-hardened 18-8 grades.
ASTM A193 / ASME SA-193ASTM A193 Grade B8 Class 1 (304 Stainless)
304 stainless bolting — Class 1 for corrosion resistance and cryogenic-to-1500 °F service, Class 2 strain hardened to 125 ksi for strength.
ASTM A193 / ASME SA-193ASTM A193 Grade B8N Class 1B (304N Stainless)
304N stainless bolting — nitrogen lifts the solution-treated yield to 35 ksi and tensile to 80 ksi without cold work, for larger diameters and higher design stresses.