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A193 B7 A194 2H
QS Fastener: A193 B7 A194 2H
Name: ASTM A193 B7 A194 2H Screw
Size: 1 Inch
Standard: Bolt Standard B18.31.2, Nut Standard B18.2.2
Type: Full Thread Stud with Two Nuts
Thread: 8 UNC
Material: ASTM A193 B7 A194 2H
Surface: Black Oxide
Size: 1 Inch
Standard: Bolt Standard B18.31.2, Nut Standard B18.2.2
Type: Full Thread Stud with Two Nuts
Thread: 8 UNC
Material: ASTM A193 B7 A194 2H
Surface: Black Oxide
Quantity
ASTM A193 B7 A194 2H Fasteners – The High-Strength Solution Designed for High-Temperature and High-Pressure Applications! Manufactured from A193 B7 chromium-molybdenum alloy steel (tensile strength ≥125 ksi) paired with A194 2H heavy hex nuts, featuring black oxide surface treatment for exceptional mechanical performance and corrosion resistance. Compliant with B18.31.2 bolt and B18.2.2 nut standards, the double-nut locking design ensures vibration resistance under extreme conditions, making it the ideal choice for petroleum, chemical, and energy equipment.
In high-temperature environments, the mechanical properties of ASTM A193 B7 A194 2H Fastener components may degrade significantly due to microstructural changes. However, A193 B7 (chromium-molybdenum alloy steel) achieves outstanding high-temperature strength retention through optimized alloy design and heat treatment processes.
1. Metallurgical Principles of High-Temperature Strength in A193 B7 A194 2H Fastener
The key advantage of A193 B7 material lies in its chromium-molybdenum (Cr-Mo) alloy system:
- Chromium (0.75–1.20%): Forms stable carbides (e.g., Cr₇C₃), inhibiting grain boundary diffusion at high temperatures and delaying creep.
The key advantage of A193 B7 material lies in its chromium-molybdenum (Cr-Mo) alloy system:
- Chromium (0.75–1.20%): Forms stable carbides (e.g., Cr₇C₃), inhibiting grain boundary diffusion at high temperatures and delaying creep.
- Molybdenum (0.15–0.25%): Raises recrystallization temperature and enhances solid-solution strengthening, particularly above 400°C where molybdenum carbides (Mo₂C) pin dislocation movement.
- Heat Treatment: The tempered sorbite structure obtained through quenching and tempering maintains uniform precipitate distribution, preventing accelerated softening.
Compared to standard carbon steel (e.g., A307):
The A193 B7 bolt in the A193 B7 A194 2H Fastener assembly demonstrates significantly superior carbide stability at high temperatures, while the A194 2H Fastener nut's design ensures reliable joint integrity.
The A193 B7 bolt in the A193 B7 A194 2H Fastener assembly demonstrates significantly superior carbide stability at high temperatures, while the A194 2H Fastener nut's design ensures reliable joint integrity.
2. High-Temperature Performance Data of A193 B7 A194 2H Fastener
Per ASTM E21 testing and ASME BPVC standards:
- A193 B7 performance at 425°C:
- Tensile strength retention: 80% of room-temperature strength (≥690 MPa).
- Yield strength retention: 75% (from 725 MPa to ~540 MPa).
- When paired with A194 2H nuts, creep rupture time exceeds 1,000 hours (vs. only 100 hours for A307).
Per ASTM E21 testing and ASME BPVC standards:
- A193 B7 performance at 425°C:
- Tensile strength retention: 80% of room-temperature strength (≥690 MPa).
- Yield strength retention: 75% (from 725 MPa to ~540 MPa).
- When paired with A194 2H nuts, creep rupture time exceeds 1,000 hours (vs. only 100 hours for A307).
- In flange connection tests, the A193 B7 A194 2H Fastener assembly reduces preload loss by 60% compared to carbon steel combinations.
3. Engineering Application Case
At a refinery hydrotreater (400°C), carbon steel bolts were replaced with the ASTM A193 B7 A194 2H Fastener assembly after leakage occurred within 6 months, achieving:
- Retightening interval extended from 3 months to 3 years.
- Vibration loosening risk reduced by A194 2H's secondary locking design.
- High-temperature creep deformation decreased by 80% thanks to A193 B7 material.
At a refinery hydrotreater (400°C), carbon steel bolts were replaced with the ASTM A193 B7 A194 2H Fastener assembly after leakage occurred within 6 months, achieving:
- Retightening interval extended from 3 months to 3 years.
- Vibration loosening risk reduced by A194 2H's secondary locking design.
- High-temperature creep deformation decreased by 80% thanks to A193 B7 material.
4. Selection Guidelines
- Temperature range for A193 B7 A194 2H Fastener: -29°C to 425°C (up to 450°C for short-term exposure).
- ASME BPVC VIII mandates: Pressure vessels >350°C must use A193 B7 bolts.
- A194 2H nut hardness (HRC 22-34) prevents thread galling.
- Temperature range for A193 B7 A194 2H Fastener: -29°C to 425°C (up to 450°C for short-term exposure).
- ASME BPVC VIII mandates: Pressure vessels >350°C must use A193 B7 bolts.
- A194 2H nut hardness (HRC 22-34) prevents thread galling.
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