Related Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
ASTM A320 Grade B8M Class 2
Strain Hardened 316 Molybdenum-Bearing High-Strength Continuous & Double-End Studs
ASTM A320 Grade B8M Class 2 receive cold strain hardening to provide elevated mechanical strength in molybdenum-bearing stainless steel. These 316 studs achieve 125 ksi tensile and 100 ksi yield strength for high-pressure flanged joints in corrosive process streams. B8M Class 2 are specified for desalination plant flanges, pharmaceutical reactor joints, and sour service manways where the combination of high preload, thread engagement, and molybdenum-enhanced corrosion resistance ensures long-term gasket compression and joint integrity.
ASTM A320/A320M Grade B8M Properties
ASTM A320/A320M Grade B8M Chemical Requirements
Austenitic Steels
| Grade Symbol | UNS Designation | C, max | Mn, max | P, max | S, max | Si, max | Ni | Cr | Mo | |
|---|---|---|---|---|---|---|---|---|---|---|
| ASTM A320 B8M | S31600(316) | Range,% | 0.08 | 2.00 | 0.045 | 0.030, max | 1.00 | 10.0 - 14.0 | 16.0 - 18.0 | 2.00 - 3.00 |
| Product Variation, % Over or Under | 0.01 over | 0.04 over | 0.010 over | 0.005 over | 0.05 over | 0.15 | 0.20 | 0.10 | ||
ASTM A320/A320M Grade B8M Mechanical Requirements
Austenitic Steels
| Grade and Class | Diameter, in. [mm] | Heat Treatment | Tensile Strength, min, ksi [MPa] | Yield Strength, min, ksi [MPa] (0.2 % offset) | Elongation in 2 in. or 50 mm, min, % | Reduction of Area, min, % | Hardness, max |
|---|---|---|---|---|---|---|---|
| ASTM A320 B8M Class 2 | 3/4 [20] and under | carbide solution treated and strain hardened | 110 [760] | 95 [655] | 15 | 45 | 321 HBW or 35 HRC |
| over 3/4 to 1 [20 to 25], incl | 100 [690] | 80 [550] | 20 | 45 | 321 HBW or 35 HRC | ||
| over 1 to 11/4 [25 to 32], incl | 95 [655] | 65 [450] | 25 | 45 | 321 HBW or 35 HRC | ||
| over 11/4 to 11/2 [32 to 40], inclA | 90 [620] | 50 [345] | 30 | 45 | 321 HBW or 35 HRC |
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