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Alloy Steel Stud Bolt and Nut
QS Fastener: Alloy Steel Stud Bolt and Nut
Name: Alloy Steel Stud Bolt and Nut
Material: ASTM A193 B7,A194 2H
Finish: Black Oxide
Size: 3/4 Inch
Type: Fully Threaded
Length: 80mm
Ends: Both Ends with Chamfer
Application: For Flange and Pipeline Equipment Installation
Material: ASTM A193 B7,A194 2H
Finish: Black Oxide
Size: 3/4 Inch
Type: Fully Threaded
Length: 80mm
Ends: Both Ends with Chamfer
Application: For Flange and Pipeline Equipment Installation
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Alloy Steel Stud Bolt and Nut Specially designed for high-pressure and high-temperature conditions, the Alloy Steel Stud Bolt and Nut combines an ASTM A193 B7 alloy steel stud with an ASTM A194 Grade 2H heavy-duty nut. With surface treatments that significantly enhance rust and wear resistance, this product features a 3/4-inch × 80mm specification, full-thread design, and chamfered ends for easy installation. It meets pipeline connection requirements in petroleum, chemical, and energy industries, providing reliable and long-lasting fastening performance.
Corrosion Resistance of Alloy Steel Stud Bolt and Nut
The Alloy Steel Stud Bolt and Nut excels in harsh environments, including acidic media, high temperature/pressure, and marine climates, thanks to its optimized alloy composition and customizable surface protection.
The Alloy Steel Stud Bolt and Nut excels in harsh environments, including acidic media, high temperature/pressure, and marine climates, thanks to its optimized alloy composition and customizable surface protection.
(1) Alloy Composition for Corrosion Resistance
The B7 material (UNS G41400) in Alloy Steel Stud Bolt and Nut contains precisely controlled chromium (Cr) and molybdenum (Mo) for dual protection:
- Chromium (Cr: 0.80–1.10%):
- Forms a dense Cr₂O₃ oxide layer, reducing oxidation rates by 60% versus carbon steel at 400°C.
- Provides passivation to resist electrochemical corrosion, especially in chloride-rich environments (e.g., seawater or chemical solutions).
The B7 material (UNS G41400) in Alloy Steel Stud Bolt and Nut contains precisely controlled chromium (Cr) and molybdenum (Mo) for dual protection:
- Chromium (Cr: 0.80–1.10%):
- Forms a dense Cr₂O₃ oxide layer, reducing oxidation rates by 60% versus carbon steel at 400°C.
- Provides passivation to resist electrochemical corrosion, especially in chloride-rich environments (e.g., seawater or chemical solutions).
- Molybdenum (Mo: 0.15–0.25%):
- Improves resistance to sulfide stress corrosion cracking (SSC), meeting NACE MR0175 standards (safe for H₂S partial pressure ≤0.3 psi).
- Enhances grain boundary stability, minimizing intergranular corrosion (rate <0.1 mm/year at pH≥3).
- Improves resistance to sulfide stress corrosion cracking (SSC), meeting NACE MR0175 standards (safe for H₂S partial pressure ≤0.3 psi).
- Enhances grain boundary stability, minimizing intergranular corrosion (rate <0.1 mm/year at pH≥3).
(2) Surface Treatment Options
To address varying corrosive conditions, Alloy Steel Stud Bolt and Nut offers multiple surface treatments:
To address varying corrosive conditions, Alloy Steel Stud Bolt and Nut offers multiple surface treatments:
| Treatment | Mechanism | Salt Spray Resistance (ASTM B117) | Ideal Environment | Max Temperature |
| Hot-Dip Galvanizing | Zinc layer (50–80µm) sacrificial protection | 500–800 hours | Mild industrial/dry atmospheres | 200°C |
| Dacromet | Zn/Al flakes + chromate passivation | 1000+ hours | Marine/high-humidity | 300°C |
| PTFE Coating | Polytetrafluoroethylene (20–30µm) | 1500+ hours | Strong acids (pH 1–12) | 260°C |
| Nitriding | Fe₄N hardened layer (0.1–0.3mm) | N/A (inert) | High-temperature wear | 450°C |
(3) Performance in Real-World Conditions
- Marine Exposure: Dacromet-treated Alloy Steel Stud Bolt and Nut showed 80% lower corrosion than standard galvanized parts in 30-year Florida marine tests.
- Marine Exposure: Dacromet-treated Alloy Steel Stud Bolt and Nut showed 80% lower corrosion than standard galvanized parts in 30-year Florida marine tests.
- Acidic Oilfield Conditions: PTFE-coated units survived 5 years in H₂S (10 ppm)/CO₂ environments without stress cracks (per NACE TM0177).
- High-Temperature Air: Untreated B7 material gained <2 mg/cm² after 1000 hours at 400°C (ASTM G54).
(4) Selection Guide
- Budget Option: Hot-dip galvanizing (cost-effective for dry environments).
- Balanced Performance: Dacromet + sealant (1200+ salt spray hours).
- Chemical Resistance: PTFE coating (for extreme pH, avoid abrasion).
- Budget Option: Hot-dip galvanizing (cost-effective for dry environments).
- Balanced Performance: Dacromet + sealant (1200+ salt spray hours).
- Chemical Resistance: PTFE coating (for extreme pH, avoid abrasion).
📌 Key Note:
While B7 material’s inherent corrosion resistance is lower than stainless steel (e.g., A193 B8M), surface-treated Alloy Steel Stud Bolt and Nut meets most industrial needs at 40% of the cost. Always consider environment, temperature, and mechanical loads when selecting.
While B7 material’s inherent corrosion resistance is lower than stainless steel (e.g., A193 B8M), surface-treated Alloy Steel Stud Bolt and Nut meets most industrial needs at 40% of the cost. Always consider environment, temperature, and mechanical loads when selecting.
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