ASTM A193 B8M Class 2 Stud Bolt,A193 B8M Class 2 Hex Bolt,A194 Grade 8M Hex nuts
High-Strength Austenitic Stainless Steel Fasteners for Corrosive Service
ASTM A193 B8M Class 2 stud bolts and hex bolts, used together with ASTM A194 Grade 8M hex nuts, are high-strength austenitic stainless steel fasteners designed for severe corrosive environments. Manufactured from molybdenum-bearing stainless steel (Type 316) and strengthened through Class 2 strain hardening, these fasteners provide superior resistance to chloride corrosion, pitting, and stress corrosion cracking, making them ideal for offshore, chemical, and marine applications.
What Is ASTM A193 B8M Class 2?
ASTM A193 B8M is the molybdenum-enhanced version of B8 stainless steel fasteners, equivalent to AISI 316 stainless steel.
Class 2 indicates strain-hardened condition, offering significantly higher strength compared to Class 1 (solution annealed).
ASTM A193 Grade B8M Class 2 Bolts are manufactured from AISI 316 Stainless Steel carbide solution treated with Strain Hardening
Chemical Composition
(Weight %, per ASTM A193 requirements for B8M)
| Element | Composition (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Silicon (Si) | ≤ 1.00 |
| Chromium (Cr) | 16.00 – 18.00 |
| Nickel (Ni) | 10.00 – 14.00 |
| Molybdenum (Mo) | 2.00 – 3.00 |
This composition corresponds to AISI 316 / 316L stainless steel, providing excellent corrosion resistance, especially in chloride-containing environments.
Mechanical Properties (Class 2)
Mechanical properties vary with fastener diameter. Typical minimum requirements are shown below:
| Diameter Range | Tensile Strength (min) | Yield Strength (0.2% offset, min) | Elongation (min) | Reduction of Area (min) | Hardness (max) |
|---|---|---|---|---|---|
| ≤ 3/4 in | 110 ksi (760 MPa) | 95 ksi (655 MPa) | 15 % | 45 % | 321 HB / 35 HRC |
| > 3/4 – 1 in | 100 ksi (690 MPa) | 80 ksi (550 MPa) | 20 % | 45 % | 321 HB / 35 HRC |
| > 1 – 1¼ in | 95 ksi (655 MPa) | 65 ksi (450 MPa) | 20 % | 45 % | 321 HB / 35 HRC |
| > 1¼ – 1½ in | 90 ksi (620 MPa) | 50 ksi (345 MPa) | 30 % | 45 % | 321 HB / 35 HRC |
Material Designations & Equivalents
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Stud / Bolt: ASTM A193 B8M Class 2
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Nut: ASTM A194 Grade 8M
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Base Material: AISI 316 / UNS S31600
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EN Equivalent: EN 1.4401 / 1.4404 (approx.)
Material: A193 B8M Stud Bolt and A194 8M Hex NutsStub bolts Material: ASTM A193 B8M.
Nuts material: ASTM A194 8M.
Standard: ASME B18.2.1, ASME B18.2.2.
We also can apply xylan fluorocarbon coating on the ASTM A194 GRADE 8M Class 2 Stud bolts,Xylan 1014 with red colors.
Xylan 1014 coated ASTM A194 GRADE 8M Class 2 Stud bolts
How to order our ASTM A194 GRADE 8M Class 2 Stud bolts？
Example#1，
STUD BOLTS ASTM A193 GRD B8M CLASS 2
02 HEAVY HEX NUT ASTM A194 GRD 8M
02 FLAT WASHER ASME B18.21.1, Type A, Narrow SS316
5/8“ UNC* 120mm，Quantity ：120 sets
