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Incoloy 825 Bolt and Nut
QS Fastener: Incoloy 825 Bolt and Nut
Name: Incoloy 825 Bolt and Nut
Material: Incoloy 825, 2.4858
Standard:DIN 933, UNS N08825, NS1402
Length: 60 mm
Hardness: Max. 200 HB
Size: M10
Feature: Good resistance to stress corrosion cracking
Application: For Industrial areas where the temperature does not exceed 550 degrees Celsius
Material: Incoloy 825, 2.4858
Standard:DIN 933, UNS N08825, NS1402
Length: 60 mm
Hardness: Max. 200 HB
Size: M10
Feature: Good resistance to stress corrosion cracking
Application: For Industrial areas where the temperature does not exceed 550 degrees Celsius
Quantity
Manufactured from high-performance nickel-iron-chromium alloy (UNS N08825/2.4858), the Incoloy 825 Bolt and Nut are available in standard M10×60mm specifications (DIN 933) with customizable production options. With hardness ≤200 HB, they are engineered for high-temperature industrial environments up to 550°C. Their exceptional resistance to stress corrosion cracking (SCC) makes them the ideal choice for harsh applications such as acidic oil & gas systems and chemical reactors, delivering reliable high-pressure sealing performance.
1. Material Properties of Incoloy 825 Bolt and Nut
The Incoloy 825 Bolt and Nut derive their high-temperature stability from a nickel-chromium-molybdenum matrix enhanced with copper, ensuring mechanical integrity and oxidation resistance under extreme conditions.
The Incoloy 825 Bolt and Nut derive their high-temperature stability from a nickel-chromium-molybdenum matrix enhanced with copper, ensuring mechanical integrity and oxidation resistance under extreme conditions.
(1) Long-Term Service Temperature Range (-200°C to 550°C)
- Low-Temperature Toughness (-200°C):
- The high nickel content (≥38%) significantly lowers the ductile-to-brittle transition temperature.
- In liquid nitrogen (-196°C), the Charpy V-notch impact energy remains ≥100J (ASTM E23), far exceeding 304 stainless steel (~50J).
- High-Temperature Strength (550°C):
- At 550°C continuous service, the 0.2% yield strength maintains ≥180MPa (ASTM B409), outperforming 316L (~120MPa under the same conditions).
- Low-Temperature Toughness (-200°C):
- The high nickel content (≥38%) significantly lowers the ductile-to-brittle transition temperature.
- In liquid nitrogen (-196°C), the Charpy V-notch impact energy remains ≥100J (ASTM E23), far exceeding 304 stainless steel (~50J).
- High-Temperature Strength (550°C):
- At 550°C continuous service, the 0.2% yield strength maintains ≥180MPa (ASTM B409), outperforming 316L (~120MPa under the same conditions).
(2) Short-Term High-Temperature Resistance (650°C)
- Instantaneous High-Temperature Strength:
- After short-term exposure (≤100h) at 650°C, the tensile strength retention remains ≥85% (initial 586MPa → ≥500MPa), whereas 316L degrades to ~400MPa.
- Instantaneous High-Temperature Strength:
- After short-term exposure (≤100h) at 650°C, the tensile strength retention remains ≥85% (initial 586MPa → ≥500MPa), whereas 316L degrades to ~400MPa.
- Phase Stability Limitation:
- Above 650°C, potential σ-phase (FeCr) and μ-phase (Ni-Mo) precipitation may reduce toughness (elongation may drop below 15%), making Incoloy 825 Bolt and Nut unsuitable for prolonged use above this temperature.
- Above 650°C, potential σ-phase (FeCr) and μ-phase (Ni-Mo) precipitation may reduce toughness (elongation may drop below 15%), making Incoloy 825 Bolt and Nut unsuitable for prolonged use above this temperature.
(3) High-Temperature Oxidation Behavior (≤800°C)
The oxidation resistance of Incoloy 825 Bolt and Nut relies on the formation of a protective Cr₂O₃-Al₂O₃ composite oxide layer:
- Oxidation Kinetics:
- In static air at 800°C, the oxidation rate is ~0.015 mg/(cm²·h) (ASTM G54), with annual oxide layer growth ≤0.05mm.
- Comparatively, 316L exhibits 8× higher oxidation rates (0.12 mg/(cm²·h)) under the same conditions.
The oxidation resistance of Incoloy 825 Bolt and Nut relies on the formation of a protective Cr₂O₃-Al₂O₃ composite oxide layer:
- Oxidation Kinetics:
- In static air at 800°C, the oxidation rate is ~0.015 mg/(cm²·h) (ASTM G54), with annual oxide layer growth ≤0.05mm.
- Comparatively, 316L exhibits 8× higher oxidation rates (0.12 mg/(cm²·h)) under the same conditions.
- Oxide Layer Stability:
- The Cr₂O₃ layer (1-2μm thick) effectively blocks oxygen diffusion at 600-800°C, with a parabolic rate constant (kp) of 3.5×10⁻¹⁴ g²/(cm⁴·s), comparable to Alloy 600 (Ni-Cr alloy).
- Failure Threshold: Above 800°C, Cr₂O₃ converts to volatile CrO₃, leading to oxide spallation (oxidation rate surges to >0.5 mg/(cm²·h)).
- The Cr₂O₃ layer (1-2μm thick) effectively blocks oxygen diffusion at 600-800°C, with a parabolic rate constant (kp) of 3.5×10⁻¹⁴ g²/(cm⁴·s), comparable to Alloy 600 (Ni-Cr alloy).
- Failure Threshold: Above 800°C, Cr₂O₃ converts to volatile CrO₃, leading to oxide spallation (oxidation rate surges to >0.5 mg/(cm²·h)).
2. Industrial Applications of Incoloy 825 Bolt and Nut
(1) Preferred Applications
- Sour Oil & Gas Environments (400-550°C):
- Incoloy 825 Bolt and Nut outperform duplex 2205 in sulfide corrosion resistance (Ni inhibits FeS formation), ensuring long-term reliability in hydroprocessing reactors.
(1) Preferred Applications
- Sour Oil & Gas Environments (400-550°C):
- Incoloy 825 Bolt and Nut outperform duplex 2205 in sulfide corrosion resistance (Ni inhibits FeS formation), ensuring long-term reliability in hydroprocessing reactors.
- Cryogenic-to-Moderate Thermal Cycling (e.g., LNG Valve Fasteners):
- The thermal expansion coefficient (14.5×10⁻⁶/°C) closely matches carbon steel, minimizing thermal stress cracking risks.
- The thermal expansion coefficient (14.5×10⁻⁶/°C) closely matches carbon steel, minimizing thermal stress cracking risks.
(2) Cautionary Scenarios
- Prolonged Exposure >600°C in Oxidizing Atmospheres:
- Recommended alternatives: Alloy 625 (Nb-strengthened) or 601 (high-Al content).
- Prolonged Exposure >600°C in Oxidizing Atmospheres:
- Recommended alternatives: Alloy 625 (Nb-strengthened) or 601 (high-Al content).
- Dynamic Loading + High Temperature (e.g., Gas Turbine Bolts):
- For high-cycle fatigue resistance, age-hardening heat treatment (900°C/4h) is advised to refine grain boundaries.
- For high-cycle fatigue resistance, age-hardening heat treatment (900°C/4h) is advised to refine grain boundaries.
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