Alloy 17-4PH

Alloy 17-4PH, also known as UNS S17400, Type 630, or Stainless Steel 17-4, is a chromium-nickel-copper precipitation-hardening martensitic stainless steel with an addition of niobium. It is normally supplied in an 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. Among these, the H900 condition is a widely favoured heat treatment for significantly improving the alloy’s hardness and strength.

Alloy 17-4PH stainless steel can be fabricated and welded by standard industry practices but care must be taken to apply heat treatment after welding to restore corrosion resistance. The alloy is also magnetic.

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

We stock a comprehensive range of round bars (various conditions), sizes between 14mm and 280mm in diameter and Flat Bars with a thickness between 8mm and 118mm and a width with max. 250mm. We are also offering:

• General forging
• Rings
• Blocks
• Primarily manufactured in: Europe, US
• Primarily manufactured in: Europe, US

• EN/DIN 1.4542/ X5CrNiCuNb16.4/ AFNOR Z6CNU17-O4/ ASME SA 693
• ASTM-A564/ Grade 630/ UNS S17400/ JIS SUS630
• AMS 5643/5604 / 5662 / EN10088-3 H900/H1025/ H1075/ H1150D

Material may also be supplied against Customer specifications, subject to enquiry.

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, %

17-4PH stainless steel is a versatile martensitic precipitation-hardening alloy widely used across various industries due to its unique properties.

• Tailorable Properties via Heat Treatment: 17-4PH’s properties can be customised through heat treatment, allowing optimising of strength, hardness, and toughness for specific applications.
• Superior Formability and Weldability: This alloy offers superior formability and weldability compared to other stainless steels. It is easily processed and welded using standard practices, contributing to its versatility and cost-effectiveness.
• Good Corrosion Resistance: 17-4PH maintains performance in challenging environments and temperatures up to 300°C, making it ideal for corrosive applications.
• High Strength-to-Weight Ratio: 17-4PH provides yield strengths up to ~160 ksi and ultimate tensile strengths up to ~210 ksi, while maintaining ductility and hardness. This high strength-to-weight ratio makes it valuable for weight-sensitive applications.

17-4PH stainless steel can be used for forging due to its robust properties, allowing it to form components that withstand high stress and resist heat treatment distortion. However, forging needs to be carried out at ~1010–1140 °C and after which, alloy must be solution-annealed and cooled to form martensite

Alloy 17-5 PH is hardened by heating solution-treated material to 482°C to 621°C for 1-4 hours, then air-cooled below 32°C for martensite transformation. Tempered 17-4 stainless steel can achieve Brinell hardness up to 388 and Rockwell hardness up to C40.

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.

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

The corrosion resistance of Alloy 17-4PH is comparable to AISI 304 stainless steel, but is generally superior to 400 series stainless steel. It is used in applications where the combination of moderate corrosion resistance and unusual high strength is required. Alloy 17-4PH in condition A should not generally be put into service; the Alloy lacks strength and stress corrosion resistance and is more sensitive to chloride stress corrosion cracking than the aged Alloy.

We supply alloy 17-4 PH in numerous configurations, catering to different manufacturing processes and end-use applications:

• 17-4 PH Bars – Fundamental for machining applications
• 17-4PH Plates – Ideal for aerospace/industrial structures and heavy-duty fabrication
• 17-4PH Sheets – Commonly used for lighter gauge applications and intricate parts
• 17-4 PH Tubes – Applied in hollow shafts, structural tubing, and aerospace/industrial ducting

For specific inquiries regarding the availability of 17-4 stainless steel, please feel free to message our team.