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M20 Hex Nut
QS Fastener: M20 Hex Nut
Name : M20 Hex Nut ASTM A194 7M
Size: M20
Material: ASTM A194 7M
Coating: Teflon Coated Red
Thread Standard: ASME B1.13M
Class: Metric Thread Class 6H
Application: For the Construction and Maintenance of Mining Equipment
Size: M20
Material: ASTM A194 7M
Coating: Teflon Coated Red
Thread Standard: ASME B1.13M
Class: Metric Thread Class 6H
Application: For the Construction and Maintenance of Mining Equipment
Quantity
M20 Hex Nut is a high-strength, corrosion-resistant fastener specifically designed for mining equipment. Manufactured from ASTM A194 7M alloy steel and compliant with ASME B1.13M 6H metric thread standards, M20 Hex Nut combines exceptional mechanical properties with long-term protection. Its distinctive red Teflon coating effectively resists moisture, dust, and chemical corrosion in mining environments, significantly extending equipment maintenance intervals. As the ideal choice for heavy-duty mining machinery such as excavators and crushers, M20 Hex Nut ensures secure connections under high-vibration and heavy-load conditions.
Heat treatment is the core process determining the performance of ASTM A194 7M alloy steel used in M20 Hex Nut, primarily comprising quenching + tempering (QT) and hydrogen embrittlement relief. Through precise control of heating temperature, cooling rate, and soaking time, this process optimizes the material's microstructure, enabling M20 Hex Nut to achieve balanced high strength, toughness, and hydrogen embrittlement resistance.
1. Quenching Process
Objective: Obtain high-strength martensitic structure to enhance M20 Hex Nut's hardness and tensile strength.
Objective: Obtain high-strength martensitic structure to enhance M20 Hex Nut's hardness and tensile strength.
- Heating temperature: 880-950°C (adjusted per steel composition)
- Lower limit (880°C) ensures complete austenitization, preventing undissolved ferrite from affecting M20 Hex Nut's hardenability
- Upper limit (950°C) prevents grain coarsening (must comply with ASTM E112 Grade 5-8 requirements)
- Lower limit (880°C) ensures complete austenitization, preventing undissolved ferrite from affecting M20 Hex Nut's hardenability
- Upper limit (950°C) prevents grain coarsening (must comply with ASTM E112 Grade 5-8 requirements)
- Soaking time: 1.5-2 min/mm (based on effective section thickness) ensures uniform heat penetration in M20 Hex Nut
- Cooling medium: Fast oil quenching (e.g., Gulf Oil 70 or equivalent) at 80-120°C/s to avoid distortion/cracking risks from water quenching
2. Tempering Process
Objective: Reduce M20 Hex Nut's quench brittleness while balancing strength and toughness.
Objective: Reduce M20 Hex Nut's quench brittleness while balancing strength and toughness.
- Temperature range: 540-680°C (adjusted per target hardness HRC 22-30)
- 540-600°C: For M20 Hex Nut requiring high strength (tensile strength ≥1000 MPa)
- 600-680°C: For enhanced toughness (impact energy ≥54 J)
- 540-600°C: For M20 Hex Nut requiring high strength (tensile strength ≥1000 MPa)
- 600-680°C: For enhanced toughness (impact energy ≥54 J)
- Cooling method: Air cooling (avoid water cooling to prevent new stresses)
3. Hydrogen Embrittlement Relief
Objective: Eliminate hydrogen atoms absorbed during processing to prevent delayed fracture in M20 Hex Nut.
Objective: Eliminate hydrogen atoms absorbed during processing to prevent delayed fracture in M20 Hex Nut.
- Parameters: 200±10°C × 24 hours (per ISO 9587 standard)
- Verification: Hydrogen content testing (requirement ≤0.2 ppm)
- Verification: Hydrogen content testing (requirement ≤0.2 ppm)
4. Industry Comparison
- Carbon steel nuts don't require hydrogen relief, whereas M20 Hex Nut's Cr/Mo alloy composition mandates this process
- In H₂S environments, M20 Hex Nut's hydrogen treatment reduces sudden fracture risk by over 90%
- Carbon steel nuts don't require hydrogen relief, whereas M20 Hex Nut's Cr/Mo alloy composition mandates this process
- In H₂S environments, M20 Hex Nut's hydrogen treatment reduces sudden fracture risk by over 90%
Conclusion
Through precision quenching-tempering and hydrogen control, M20 Hex Nut delivers both high load capacity and reliability in harsh conditions. Users should optimize parameters based on operational factors (temperature/medium) and strictly monitor anti-hydrogen measures to maximize M20 Hex Nut's performance.
Through precision quenching-tempering and hydrogen control, M20 Hex Nut delivers both high load capacity and reliability in harsh conditions. Users should optimize parameters based on operational factors (temperature/medium) and strictly monitor anti-hydrogen measures to maximize M20 Hex Nut's performance.
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