17-4PH
17-4PH is a typical martensitic precipitation-hardening stainless steel, combining corrosion resistance and ultra-high strength after aging heat treatment, widely used for high-load precision structural parts.
Typical Chemical Composition
- Chromium (Cr): 15.0%–17.5% – Provides basic rust and oxidation resistance
- Nickel (Ni): 3.0%–5.0% – Stabilizes matrix structure, improves toughness
- Copper (Cu): 3.0%–5.0% – Main precipitation strengthening element to boost hardness and tensile strength during aging
- Niobium (Nb): 0.15%–0.45% – Refines grains, inhibits carbide precipitation
- Carbon (C): ≤0.07% – Low carbon to reduce intergranular corrosion
- Balance: Iron with minor trace elements
Core Material Properties
- Adjustable High Strength & Hardness Strength and hardness can be customized via different aging temperatures (H900/H1025/H1075/H1150/H1175). The highest hardness reaches over 44 HRC, outstanding for wear-resistant and load-bearing components.
- Good Corrosion Resistance Corrosion performance is better than common 400-series martensitic stainless steel, close to 304 austenitic steel; resists atmospheric corrosion, fresh water and mild chemical media.
- Heat-Treatable Strengthening Feature It can be softened by solution treatment for forming/machining, then significantly hardened by low-temperature aging, which is its biggest advantage over 304/316.
- Moderate Formability Better ductility than fully martensitic stainless steel; suitable for MIM to produce complex small structural parts, no easy cracking during sintering.
- Magnetic Property Magnetic in all heat treatment states, not suitable for magnetic-sensitive electronic assemblies.
- Temperature Performance Maintains stable mechanical properties under medium-temperature working conditions; not recommended for long-term service above 315°C.
Machining & MIM Process Adaptability
- Metal Injection Molding (MIM) 17-4PH powder has stable flowability, achieves high density after debinding and sintering. Perfect for miniature gears, hinge shafts, tow hooks, medical load-bearing tools and automotive structural parts with complex thin-wall geometry.
- Compatible Surface Treatments Supports polishing, sandblasting, passivation, PVD coating, meeting both mechanical and decorative requirements.
- Standard Heat Treatment Flow Solution treatment (high temperature holding + rapid cooling) → low-temperature aging to precipitate copper-rich phases, greatly improving hardness, tensile strength and yield strength.
Advantages & Disadvantages
Advantages
- Tunable ultra-high strength and hardness via aging heat treatment
- Balanced corrosion resistance and mechanical performance, superior to 410/420 martensitic steel
- Excellent dimensional stability after heat treatment, ideal for precision transmission parts
- High toughness, resistant to impact fracture under heavy load
Disadvantages
- Higher material cost than 304
- Magnetic, cannot be used for magnetic interference-sensitive equipment
- Inferior chloride corrosion resistance compared to 316, unsuitable for long-term salt spray coastal environments
- Hardened state has reduced ductility, difficult for secondary bending forming
Typical Applications
- Power Transmission & Gear Systems: Gear shafts, lock cores, small transmission gears
- Automotive Parts: Tow hooks, high-strength interior structural brackets
- Audio Equipment: Load-bearing rotating hinges, structural brackets
- Medical Devices: High-torque surgical industrial tools, clamping forceps with heavy load
- Industrial Precision Hardware: High-strength connectors, hydraulic miniature valve parts
