17-4PH Alloy (UNS S17400)

  • High strength and hardness
  • Corrosion resistance
  • Durability and high elongation
  • Available in both commercial and industrial usage
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17-4PH stainless steel also goes by the name of alloy 630 in the stainless-steel industry. The major components of this material are copper, nickel, and chromium. It is also precipitate hardened, so it gets the term “PH” in its name.

Because of the used material 17-4PH, its major positives are its hardness and strength & it is widely found in many industries. Welding with this is also easy, so a standard fabrication shop is more than enough. It is also magnetic, which is a plus point depending on its place of use.

Common Names:

  • 17-4
  • ATI 17-4
  • UNS S17400
  • Type 630

Executive Standards:

Bar, Wire, Forging and Tube

  • AMS 5643
  • AMS 5622
  • AMS 5642
  • ASTM A564
  • ASTM A484
  • ASME SA564

Sheet, Strip, and Plate

  • AMS 5604
  • ASTM A693 Grade 630


  • AMS 5825
  • ASME SA693
  • ASME SA705
  • ASTM A705

Chemical Properties:

Iron (%)69.03
Chromium (%)17.75
Nickel (%)5.00
Copper (%)5.00
Manganese (%)1.00
Silicon (%)1.00
Others (%)Remainder

Mechanical Properties:

Yield Strength (MPa)1000
Yield Strength (ksi)145
Ultimate Tensile Strength (MPa)1103
Ultimate Tensile Strength (ksi)160
Modulus of Elasticity (GPa)190-210
Modulus of Elasticity (ksi)27557-30458
Elongation 5%

(Rockwell C)


Physical Properties:

Density  lb/in30.280
Melting Point°F2560-2625

Thermal Conductivity


Electrical Resistivity

μΩ-cm 75
Specific HeatJ/g-K460
Poisson’s RatioNo unit0.27-0.30

Key Features:

  • Corrosion resistance: Since it is stainless steel material, it has good resistance against stress corrosion cracking. After performing 17-4PH heat treatment at high temperature, more reliable and stronger stress corrosion resistance is offered by the 17-4PH H1150 variant as compared to the 17-4 H900 one.
  • High Strength: The SAE type 630 stainless steel offers excellent mechanical properties, which makes it confer high 17-4PH hardness. It results in high strength and makes this alloy suitable to be used in machines.
  • Weldability and ductility: Typically, 17-4PH stainless steel has satisfactory welding properties. The 17-4PH composition makes it extremely ductile. Hence, it is useful in the specialty steel supply industry.

Product Forms Available:

  • Pipe
  • Tube
  • Rod
  • Bars
  • Plate
  • Sheet
  • Strip


  • Biomedical
  • Food processing equipment
  • Nuclear waste management
  • Aerospace components
  • Oil and gas production units

Possible Alternative Grades:

  • 17-7PH Alloy: 17-7PH alloy has better hardness than 17-4PH stainless steel properties and provides great fatigue strength and less distortion upon heating.

Frequently Asked Questions:

  • What is the H900 condition in 17-4 alloy?

17-4 H900 is one of the assigned heat treat designations that signifies aging to occur at 900°F for 1 hour.

  • Which heat treat designation of 17-4PH has the highest hardness?

17-4 H900 hardness has a maximum value of 45 (Rockwell C).

  • Is 17-4PH stainless steel machinable?

As per 17-4PH properties, this grade is well machinable in solution-treated as well as age-hardened conditions.

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