Type 17-4 PH stainless steel, being the most commonly utilized among precipitation-hardening stainless steels, offers a valuable blend of characteristics that empower designers to enhance the dependability of their products, streamline fabrication processes, and frequently lower expenses.
It is classified as a martensitic precipitation-hardening stainless steel, known for its remarkable combination of high strength, commendable corrosion resistance, and favorable mechanical properties even at temperatures reaching 600°F (316°C). With its distinct set of properties, this alloy serves as an efficient solution for various design and production challenges.
17-4 PH stainless steel is a martensitic stainless steel that is known for its excellent mechanical properties, corrosion resistance, and toughness. It is typically used in applications where high strength and corrosion resistance are required, such as medical devices, aerospace, and automotive components.
17-4 PH stainless steel Material Specification
The UNS Number of 17-4PH stainless steel is UNS S17400. The 17-4PH stainless steel, with material specifications designated by various organizations, is known as ASME SA564, SA693, SA705, Type 630, AMS 5604, 5622, 5643, 5825, ASTM A564, A693, A705, Type 360, UNS S17400, and W. Nr./EN 1.4548.
17-4 PH stainless steel Chemical Composition
The chemical composition of 17-4 PH stainless steel is as follows:
| Element | Composition Range (wt. %) |
|---|---|
| Chromium (Cr) | 15.0 – 17.5 |
| Nickel (Ni) | 3.0 – 5.0 |
| Copper (Cu) | 3.0 – 3.5 |
| Manganese (Mn) | 1.0 max |
| Silicon (Si) | 1.0 max |
| Columbium (Cb) | 0.15 – 0.45 |
| Phosphorus (P) | 0.04 max |
| Sulfur (S) | 0.03 max |
| Carbon (C) | 0.07 max |
| Nitrogen (N) | 0.10 max |
17-4 PH stainless steel Mechanical Properties
17-4 PH stainless steel has excellent mechanical properties, including high strength, toughness, and hardness. The yield strength of 17-4 PH stainless steel is typically in the range of 175-200 ksi, and the tensile strength is typically in the range of 200-225 ksi. The hardness of 17-4 PH stainless steel is typically in the range of 35-45 HRC.
| Property | Value |
|---|---|
| Tensile Strength | 110 ksi (758 MPa) |
| Yield Strength | 100 ksi (689 MPa) |
| Elongation | 15% (in 2 inches) |
| Hardness | HRC 36-44 |
| Impact Strength | 40 ft-lb (54 J) |
| Modulus of Elasticity | 28.5 x 10^6 psi (196 GPa) |
| Density | 0.280 lb/in^3 (7.75 g/cm^3) |
| Thermal Conductivity | 9.8 BTU/hr-ft-°F (16.9 W/m-°C) |
| Coefficient of Thermal Expansion | 6.3 x 10^-6 in/in/°F (11.3 µm/m/°C) |
Corrosion Resistance
Type 17-4 PH stainless steel exhibits exceptional resistance, surpassing that of typical hardenable stainless steels, and shows similar corrosion resistance to type 304 stainless steel in most environments. Its resistance to corrosive attack has been thoroughly tested in diverse conditions found in industries like petrochemical, petroleum, paper, dairy, food processing, as well as in applications such as boat shafting.
17-4 PH stainless steel has excellent corrosion resistance, making it suitable for use in a variety of corrosive environments. It is resistant to corrosion in both acidic and alkaline solutions, and it is also resistant to corrosion from chlorides and other salts.
Toughness
17-4 PH stainless steel has excellent toughness, making it resistant to impact and wear. It is also resistant to fatigue, making it suitable for use in applications where repeated loading and unloading is expected.
Physical Properties
17-4 PH stainless steel has good physical properties, including high strength-to-weight ratio, good thermal conductivity, and good electrical conductivity. It is also resistant to thermal shock, making it suitable for use in applications where it is exposed to sudden changes in temperature.
17-4 PH stainless steel heat treatment
The heat treatment process for 17-4 PH stainless steel typically involves the following steps:
- Solution Annealing: The material is heated to a temperature between 1900-2050°F (1038-1121°C) and held at that temperature for a sufficient period of time to ensure complete dissolution of the precipitates. This step helps to restore the material to a fully austenitic structure.
- Quenching: After the solution annealing step, the material is rapidly cooled by quenching in water, oil, or air to room temperature. This rapid cooling is necessary to prevent the re-formation of precipitates and promote the formation of martensite.
- Aging: The quenched material is then subjected to a low-temperature aging treatment, typically around 900-1150°F (482-621°C), for a specific duration. This step allows the precipitation of fine and uniformly distributed precipitates, which significantly contribute to the material’s strength and hardness.
Applications
17-4 PH stainless steel is used in a variety of applications where high strength, corrosion resistance, and toughness are required. Some common applications include:
- Medical devices
- Aerospace
- Automotive components
- Chemical processing
- Oil and gas
- Power generation
Conclusion
17-4 PH stainless steel is a versatile material that has excellent mechanical, corrosion, and toughness properties. It is used in a variety of applications where these properties are required.
