17-4 PH stainless steel（17-4 stainless steel） is a type of martensitic stainless steel that also has some austenitic properties. It is also known as SAE Type 630 stainless steel or UNS S17400, and is a precipitation hardening stainless steel.
What does 17-4 Mean?
The “17” in 17-4 stainless steel refers to the 17% chromium content, while the “4” indicates around 4% nickel content. This unique chemical composition gives the material distinct advantages in performance.
Chemical Composition of 17-4 Stainless Steel
The typical chemical composition of 17-4 stainless steel includes chromium (15-17.5%), nickel (3-5%), copper (3-5%), and small amounts of carbon, manganese, silicon, and other elements. The combination of these elements ensures high strength and excellent corrosion resistance.
Element | Symbol | Content Range (%) |
Chromium | Cr | 15.0 – 17.5 |
Nickel | Ni | 3.0 – 5.0 |
Copper | Cu | 3.0 – 5.0 |
Carbon | C | ≤ 0.07 |
Manganese | Mn | ≤ 1.00 |
Silicon | Si | ≤ 1.00 |
Sulfur | S | ≤ 0.03 |
Phosphorus | P | ≤ 0.03 |
Molybdenum | Mo | ≤ 0.50 (optional) |
Chromium and nickel are the core elements that determine the material’s corrosion resistance and strength.
The addition of copper helps the material achieve high strength through precipitation hardening.
Other elements like carbon, manganese, and silicon contribute to the material’s mechanical properties and ease of machining.
Grades of 17-4 Stainless Steel
17-4 stainless steel is known by different names and grades in various standards worldwide. Here are some of the common names and grades:
Standard/Organization | Name/Grade | Remarks |
ASTM (USA) | 17-4PH | Common US standard name |
AISI (USA) | Type 630 | AISI classification number |
UNS (USA) | S17400 | UNS number |
AMS (Aerospace Materials) | AMS 5643 | Common in aerospace and defense industries |
EN (European Standard) | X5CrNiCuNb16-4 | European chemical naming |
DIN (Germany) | 1.4542 | German material number |
JIS (Japan) | SUS630 | Japanese standard name |
GB (China) | 0Cr17Ni4Cu4Nb | Chinese standard grade |
BS (UK) | 17/4PH | British standard |
AFNOR (France) | Z6CNU17-04 | French standard naming |
The most common name internationally is “17-4PH,” where “PH” stands for “Precipitation Hardening.”
Other names include “Type 630” under AISI and “SUS630” under the JIS standard.
Grades of 17-4 Stainless Steel
17-4 stainless steel is known by different names and grades in various standards worldwide. Here are some of the common names and grades:
Standard/Organization | Name/Grade | Remarks |
ASTM (USA) | 17-4PH | Common US standard name |
AISI (USA) | Type 630 | AISI classification number |
UNS (USA) | S17400 | UNS number |
AMS (Aerospace Materials) | AMS 5643 | Common in aerospace and defense industries |
EN (European Standard) | X5CrNiCuNb16-4 | European chemical naming |
DIN (Germany) | 1.4542 | German material number |
JIS (Japan) | SUS630 | Japanese standard name |
GB (China) | 0Cr17Ni4Cu4Nb | Chinese standard grade |
BS (UK) | 17/4PH | British standard |
AFNOR (France) | Z6CNU17-04 | French standard naming |
The most common name internationally is “17-4PH,” where “PH” stands for “Precipitation Hardening.”
Other names include “Type 630” under AISI and “SUS630” under the JIS standard.
Physical Properties of 17-4 Stainless Steel
Property | Metric Value | Imperial Value | Notes |
Density | 7.75 g/cm³ | 0.280 lb/in³ | Typical density for 17-4 PH steel |
Modulus of Elasticity | 200 GPa | 29 x 10³ ksi | Measures stiffness |
Thermal Conductivity | 18 W/m·K | 125 BTU·in/hr·ft²·°F | Thermal conductivity at 25°C |
Specific Heat Capacity | 460 J/kg·K | 0.11 BTU/lb·°F | Heat capacity at 25°C |
Electrical Resistivity | 0.79 µΩ·m | 31.1 µΩ·in | At room temperature |
Melting Point | 1400-1440°C | 2550-2625°F | Typical melting range |
Mechanical Properties of 17-4 Stainless Steel
Property | H900 (Heat Treatment) | H1025 (Heat Treatment) | Imperial Value | Notes |
Tensile Strength | 1310 MPa | 1070 MPa | 190 ksi | After H900 and H1025 heat treatments |
Yield Strength | 1170 MPa | 965 MPa | 170 ksi | After H900 and H1025 heat treatments |
Elongation | 10-15% | 15-20% | 10-15% | Percentage of elongation after fracture |
Hardness (Rockwell) | 40-47 HRC | 35-45 HRC | 40-47 HRC | Rockwell hardness after heat treatment |
Advantages of 17-4 Stainless Steel
High Strength and Hardness
After appropriate heat treatment (such as H900), 17-4 stainless steel exhibits excellent tensile strength above 1300 MPa and yield strength above 1170 MPa, making it ideal for high-load and high-stress environments.
Excellent Corrosion Resistance
It has exceptional corrosion resistance in various environments, including chlorides, seawater, and acidic conditions, making it suitable for industries like aerospace, chemicals, and marine.
Good Heat Treatment Performance
By using precipitation hardening, the material’s properties can be adjusted according to specific needs. Different heat treatment states like H900, H1025, and H1150 can enhance its strength and toughness.
High Toughness and Impact Resistance
Despite its high strength, it also maintains good toughness, especially after H1025 treatment, enabling it to withstand large impact loads.
Wide Application Range
Due to its strength, corrosion resistance, and toughness, 17-4 stainless steel is used in a variety of industries such as aerospace, chemical, medical, and energy.
17-4 Stainless Steel Casting
17-4 stainless steel is widely used in casting because it provides high strength, hardness, and excellent precipitation hardening properties. These characteristics make it suitable for casting high-performance components under demanding conditions.
Advantages
- High strength and hardness, especially after heat treatment (e.g., H900 or H1025).
- Excellent corrosion resistance, suitable for corrosive environments like chemicals and seawater.
- Good castability, allowing for the creation of complex and precise parts.
Applications of 17-4 Stainless Steel Castings:
17-4 stainless steel castings are commonly used in aerospace, chemical processing, marine engineering, and energy industries, especially for turbine blades, pump bodies, and reactors, which require high strength, corrosion resistance, and high-temperature performance.
Processing Methods for 17-4 Stainless Steel
In addition to casting, 17-4 stainless steel can be processed through various techniques to produce different components:
Machining
Includes turning, milling, grinding, and drilling. Suitable for producing parts of various shapes.
Turning: Used for cylindrical or conical parts.
Milling: Used for complex shapes and surfaces.
Grinding: For precision finishing and smooth surfaces.
Drilling: For precise hole formation.
Forging
By heating and applying pressure, forging improves the material’s density, strength, and toughness. Techniques include hot forging and cold forging.
Welding
17-4 stainless steel has good weldability and can be welded using methods like TIG and laser welding.
Stamping
Used for forming thin 17-4 stainless steel sheets into various shapes through cutting, bending, or deep drawing.
Cutting
Laser, waterjet, and plasma cutting methods are used for precise cuts and shapes.
Surface Treatment
Techniques like polishing, shot peening, electroplating, and nitriding are used to improve corrosion resistance, hardness, and appearance.
Heat Treatment
Methods like solution treatment and aging (precipitation hardening) are used to adjust the material’s internal structure and properties.
Applications of 17-4 Stainless Steel
Aerospace
It is used for aircraft structural parts, engine components, turbine blades, landing gear, and transmission devices due to its high strength and corrosion resistance.
Energy
It is used in oil and gas extraction, nuclear power, and chemical industries for critical components like pumps, valves, bearings, and heat exchangers.
Chemical
Due to its resistance to acids and bases, 17-4 stainless steel is widely used in chemical processing equipment like reactors, pipelines, and tanks.
Medical
Its biocompatibility and corrosion resistance make it ideal for surgical instruments, bone screws, and joint replacements.
Marine
Used for marine equipment, including ships and offshore platforms, due to its resistance to seawater corrosion.
Automotive
Used for high-strength, corrosion-resistant parts such as engine components, exhaust systems, and transmission parts.
Tooling
Commonly used for molds and tools because of its hardness and wear resistance.
Food Processing
Due to its excellent corrosion resistance, it is also used in food processing equipment like storage containers and conveyors.
17-4 stainless steel is a versatile material with excellent mechanical properties, corrosion resistance, and processing flexibility, making it ideal for use in demanding industries and applications.
How Can Manek Help
At Manek, we offer our clients a series of customized services specifically for 17-4 PH stainless steel and other metals, including investment casting, sand casting, die casting, CNC machining, sheet metal fabrication as well as various surface treatments.
We also provide a variety of other manufacturing capabilities. You can get quotations for free, such as 3D printing, plastic injection molding and powder coating.
FAQ
Yes, 17-4 stainless steel is magnetic. It is a martensitic precipitation-hardening steel, and martensitic steels typically exhibit magnetic properties.
The level of magnetism can vary depending on the heat treatment and processing it undergoes.
Yes, 17-4 stainless steel is generally stronger than 304 stainless steel.
17-4 is a precipitation-hardening steel that has much higher tensile and yield strength compared to 304, which is an austenitic stainless steel. After heat treatment, 17-4 can achieve tensile strengths up to 1300 MPa, while 304 typically has tensile strengths around 520-720 MPa.
Yes, 17-4 stainless steel is harder than 316 stainless steel. 17-4 stainless steel, particularly after heat treatment, can achieve high hardness levels (Rockwell hardness of 40-47 HRC), whereas 316 stainless steel is typically softer, with a hardness of around 20-30 HRC.
While 17-4 stainless steel has excellent corrosion resistance, it is not completely immune to rust or corrosion. Under harsh environments, especially in the presence of high chloride concentrations or extreme conditions, it can corrode. However, its corrosion resistance is better than that of many other steels.
No, 17-4 stainless steel is not part of the 300 series. It is classified as a martensitic precipitation-hardening steel and is commonly referred to as a 17-4 PH alloy. The 300 series includes austenitic steels, such as 304 and 316, which are different from 17-4 in terms of structure and properties.
