17-4PH H900 Properties

17-4PH H900 is a highly sought-after stainless steel alloy known for its exceptional combination of strength, corrosion resistance, and versatility. This article aims to delve into the various aspects of 17-4PH H900, including its material specification, chemical and mechanical properties, heat treatment, and equivalent materials.

Material Specification:

The UNS Number of 17-4PH Stainless steel is UNS S17400. 17-4PH H900 is a precipitation-hardening stainless steel alloy that belongs to the martensitic family. It is composed of approximately 17% chromium, 4% nickel, 4% copper, and 0.3% niobium. The material specifications for 17-4PH Steel are:

  • ASTM/ASME: UNS S17400
  • EURONORM: X5CrNiCuNb16.4
  • AFNOR: Z6CNU17-04
  • DIN: 1.4542

Chemical Properties:

The chemical composition of 17-4PH H900 plays a crucial role in determining its properties. The alloy’s primary elements include chromium, nickel, copper, and niobium. The presence of chromium provides excellent corrosion resistance, while nickel enhances toughness and ductility. Copper contributes to the alloy’s strength, and niobium aids in stabilizing the microstructure during heat treatment.

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The chemical composition of 17-4PH H900, also known as 17-4 Precipitation Hardening stainless steel in the H900 condition, typically consists of the following elements:

  • Iron (Fe): 75-77%
  • Chromium (Cr): 15-17.5%
  • Nickel (Ni): 3-5%
  • Copper (Cu): 3-5%
  • Manganese (Mn): 1% maximum
  • Silicon (Si): 1% maximum
  • Carbon (C): 0.07% maximum
  • Phosphorus (P): 0.04% maximum
  • Sulfur (S): 0.03% maximum
  • Columbium (Niobium) + Tantalum (Cb+Ta): 0.15-0.45%

Mechanical Properties:

17-4PH H900 exhibits impressive mechanical properties, making it suitable for a wide range of applications. In the H900 condition, the alloy achieves its maximum strength. Some notable mechanical properties of 17-4PH H900 include:

  • Tensile Strength: 190,000 – 200,000 psi (1310 – 1380 MPa)
  • Yield Strength: 170,000 – 180,000 psi (1170 – 1240 MPa)
  • Elongation: 8 – 10%
  • Hardness: 38 – 44 HRC

These properties make 17-4PH H900 ideal for applications that require high strength, such as aerospace components, oil and gas equipment, and medical devices.

17-4PH H900 Heat Treatment:

Heat treatment plays a crucial role in enhancing the properties of 17-4PH H900. The alloy is typically solution annealed at temperatures ranging from 1900°F to 1950°F (1040°C to 1065°C), followed by air cooling or rapid quenching. This step ensures the dissolution of precipitates and the formation of a homogeneous microstructure.

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After solution annealing, the alloy is aged at a lower temperature, typically around 900°F (480°C), to achieve precipitation hardening. This process enhances the strength and hardness of the material while maintaining its corrosion resistance.

Equivalent Materials:

While 17-4PH H900 is a unique alloy, there are some equivalent materials that offer similar properties. Some of the commonly used equivalents include:

  • AISI 630
  • UNS S17400
  • ASTM A693 Grade 630
  • X5CrNiCuNb16-4

These materials can be used as alternatives to 17-4PH H900, depending on specific requirements and availability.


17-4PH H900 is a remarkable stainless steel alloy that offers an excellent combination of strength, corrosion resistance, and versatility. Its material specification, chemical and mechanical properties, heat treatment, and equivalent materials make it a popular choice in various industries. Whether it’s aerospace, oil and gas, or medical applications, 17-4PH H900 continues to prove its worth as a reliable and high-performance material.