4140HW alloy steel is a high-quality, chromium-molybdenum steel with excellent strength and toughness properties. Here’s a breakdown of its key technical aspects:
Composition
- Carbon (C): 0.38% – 0.43%
- Chromium (Cr): 0.80% – 1.10%
- Molybdenum (Mo): 0.15% – 0.25%
- Manganese (Mn): 0.75% – 1.00%
- Silicon (Si): 0.15% – 0.30%
- Phosphorus (P): Up to 0.035% (maximum)
- Sulfur (S): Up to 0.040% (maximum)
- Iron (Fe): Balance (approximately 97.22% – 98.57%)
Mechanical Properties
- Tensile Strength: High tensile strength, typically in the range of 95,000 – 130,000 psi.
- Yield Strength: Good yield strength, often between 60,000 – 105,000 psi.
- Elongation: Exhibits decent elongation characteristics.
- Hardness: Hardened and tempered condition results in high hardness levels.
- Toughness: Excellent toughness, particularly in lower temperature environments.
Heat Treatment
- Annealing: Can be annealed for improved machinability.
- Hardening: Responds well to heat treatment and can be hardened by quenching and tempering.
Applications
- Widely used in industries requiring high strength and toughness, such as automotive, aerospace, and oil and gas.
- Ideal for making gears, axles, shafts, bolts, and other machine parts.
Fabrication and Machinability
- Machinability is rated as good, especially in the annealed condition.
- Can be welded with proper precautions but requires preheating and post-welding treatments to avoid cracking.
Physical Properties
- Density: Approximately 7.85 g/cm³.
- Thermal Conductivity: Has moderate thermal conductivity, varying with temperature.
Corrosion Resistance
- Moderate corrosion resistance and may require protective coatings in corrosive environments.
Formability
- Can be formed using conventional methods but requires controlled processing to maintain mechanical properties.
