Alloy 17-4PH

Quick Facts

Alloy 17-4PH or UNS S17400 or type 630, is a chromium-nickel-copper precipitation-hardening martensitic Stainless Steel with an addition of niobium. 17-4PH is normally supplied in annealed condition,that is Condition A. This Alloy combines high strength with good corrosion resistance. Optimal mechanical properties can be obtained by age hardening heat treatments. 17-4PH can be easily welded and processed machining practices. The Alloy is magnetic.

Typical Applications

  • Aerospace, structural parts
  • Biomedical applications
  • Chemical processing
  • Food process equipment
  • Oil & Gas applications
  • General high strength applications
  • Nuclear Waste processing and storage

Stock Range

We stock a comprehensive range of round bars (various condition), sizes between 14mm and 280mmmm in diameter Flat Bars with a thickness between 8mm – 118mm and a width with max. 250mm. We are offering as well:
General forgings
Primarily manufactured in: Europe, US
Primarily manufactured in: Europe, US

Industry Specifications

  • EN/DIN 1.4542/ X5CrNiCuNb16.4/ AFNOR Z6CNU17-O4/ ASME SA 693
  • ASTM-A564/ Grade 630/ UNS S17400/ JIS SUS630
  • AMS 5643/5604 / EN10088-3 H900/H1025/ H1075/ H1150D
  • Material may also be supplied against Customer specifications, subject to enquiry.

Chemical Analysis

Alloy 718 is hardened by the precipitation of secondary nickel- (aluminium, titanium, niobium) phases giving the alloy a combination of high strength and good corrosion resistance.

Chemical Composition, %

Alloy 17-4PH

Mechanical Properties

Alloy 17-4PH


17-4PH can be machined in both conditions; means in solution annealed and aged conditions. Machining characteristics may vary according to the hardness. Hi speed tools are accepted, but carbide tools are preferred. Standard coolant should be used. Dimensional changes as a result of the heat treatment should be taken into account, if very stringent tolerances are required.

Heat Treatment

17-4PH normally will be supplied in solution annealed condition. Mechanical properties may be achieved by
subsequent age hardening treatments. These aging treatments are referred to H900, H1025, H1075, H1150,
H1150M and H1150D, as mentioned above. The process are outlined an the nex table below. The achievable
mechanical properties are shown at the above table.

Alloy 17-4PH

Corrosion Resistance

The corrosion resistance of Alloy 17-4PH is comparable with AISI 304 stainless steel, but is in generell supirior to 400 series stainless steel. It is used in applications where the combination of moderate coirrosion resistance and unusual high strength are required. Alloy 17-4PH in condion A, should not generally put into service, the Alloy is subject to briddle fractures and more sensitive to chloride stress corrosion cracking than the aged Alloy.