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Stainless Steel 17-4

Stainless Steel 17-4, a type of precipitation hardening alloy that is in great demand, is particularly distinguished by its high strength and remarkable corrosion resistance. This stainless steel is well known for its variety, heat treatment improving its properties, is best suited for multiple applications in the industries.

Material Type

Stainless Steel 17-4 or UNS S17400 is a type of steel alloy that is expansion steel and its main ingredients include iron, chromium, copper and nickel.

Alternative Names

Stainless Steel 17-4 is often referred to by many different names depending on the composition and properties of the steel. Otherwise known as 17-4 PH (Precipitation Hardening) grade stainless steel. The number 17-4 refers to the alloy as having 17% chromium, 4% nickel and in addition to these about 4% copper which helps bring about high strength and resistance to corrosion.

Process Compatibility

Stainless Steel 17-4 is a multifaceted material with a wide spectrum of interchangeable processes which includes machining, weldability, formability, castability and surface treatment. Machining is accomplished with carbide tools and conventional techniques, heat treatment is offered to harden the component and the assemblies can be welded if proper care is exercised to avoid cracking. The as-received state of this alloy is also fabricable and can be investment cast. Elements such as passivation and anodizing are applied for protective purposes and to mask the appearance of the alloy.

Stainless Steel 17-4
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Jason xue

Kingsun's senior machining engineer

Stainless Steel 17-4 Properties

The precipitation hardenable alloy Stainless Steel 17-4 is known for its exceptional strength, good weldability, and excellent resistance to corrosion. Further, while retaining properties at high temperatures, Stainless Steel 17-4 copes well with extreme conditions, making it safe and long-lasting in critical operating environments. Here’s why you should use Stainless Steel 17-4 in your next project!
1

Mechanical Properties

  • Shear Modulus: 77.4 GPa
  • Elastic Modulus: 190-210 GPa
  • Poisson's Ratio: 0.27-0.30
  • Hardness (Brinell): 352
  • Hardness (Rockwell C): 36
2

Physical Properties

Density: 7.75 g/cm³

3

Thermal Properties

  • Thermal Expansion Coefficient: 10.8 µm/m°C
  • Thermal Conductivity: 17.9 W/mK
4

Electrical Properties

In general, stainless steels possess an intermediate range of electrical conductance.

5

Post Treatments

  • Heat Treatment: Soaked at 1038°C, cooled, and treated at various temperatures for different conditions (e.g., H900, H1025).
  • Machinability: Can be machined in the annealed condition; post-machining solution treatment is needed.
  • Welding: Common fusion and resistance welding methods are suitable.
6

Common Applications

  • Nuclear Reactors
  • Aircraft and Gas Turbines
  • Oil Fields
  • Chemical Process
  • Components
  • Paper Mills

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Frequently Asked Questions (FAQs)

Q: What is 17-4 stainless steel and what are its properties?

A: 17-4 stainless steel is an alloy in the family of martensitic steels, also referred to as martensitic stainless steel, upon which high strength and high corrosion resistance can be basis defined. It entails the combination of such mechanical properties that the material can be used in various industries, including but not limited to aerospace and chemical processing.

Q: How is 17-4 stainless steel processed?

A: The processing of 17-4 stainless steel is primarily carried out by the use of thermal methods for example solution treatment, ageing mainly precipitation hardening techniques to obtain the required values for hardness and tensile strength.

Q: What are the primary applications of 17-4 stainless steel?

A: 17-4 stainless steel is prominent for high strength and better resistance to corrosion hence finds applications in aerospace, medical devices, steam valves, pumps, gear shafts, fasteners and ball bearings.

Q: How does the corrosion resistance of 17-4 stainless steel compare to 304 stainless steel?

A: 17-4 stainless steel and 304 stainless steel both offer a fair amount of corrosion protection however when it comes to appliances, 17-4 stainless steel is preferably worse than 304 due to its higher mechanical strength. 304 on the other hand is more ductile but is installed in less severe industries.

Q: What is the chemical composition of 17-4 stainless steel?

A: The chemical composition of 17-4 stainless steel generally contains about 15-17.5% chromium, with neither nickel nor copper exceeding 3-5%, whilst the amount of the other elements with the metallic enhancing features is negligible, e.g., manganese and silicon.

Q: What does the term ‘precipitation hardening’ mean in relation to 17-4 stainless steel?

A: Precipitation hardening is a process applied on 17-4 stainless steel where the material is first heated to a solution phase and then aged at lower temperatures for other hardening phases to form. This improves the strength and hardness of the material.

Q: Is it possible to weld 17-4 stainless steel and if possible in what way?

A: Yes, 17-4 stainless steel has welding capability is there but with extra heat treatment considerations to be made before and after welding to retain mechanical properties. It is advised to employ processes such as gas tungsten arc welding (GTAW) for better outcomes.

Q: What are the physical properties of 17-4 PH stainless steel?

A: In summary, the physical properties of 17-4 PH stainless steel include very high tensile strength, heat-treatable hardness, and resistance to most corrosive chemicals, including salt water and other chemical environments.

Q: Can stainless steel 17-4 steel be turned into a magnet?

A: 17-4 stainless steel is indeed favorable to magnetism when hardened due to its martensitic structure, a feature that sets it apart from stainless steel grade 304, which is mostly non-magnetic in nature.

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