What is 17‑4 PH / S17400 round bar and why is it used? 

17‑4 PH (UNS S17400) round bar is a precipitation-hardening martensitic stainless steel known for its exceptional high strength and good corrosion resistance. It is used extensively in demanding industries like aerospace and petrochemicals for components requiring high hardness, durability, and resistance to fatigue and oxidation at temperatures up to 600°F (316°C). 

What is 17‑4 PH / S17400 Stainless Steel? 

If you are sourcing materials for high-stress environments, understanding the specific designation of your alloy is critical. 17‑4 PH stainless steel, also widely known as Type 630 stainless steel or under the Unified Numbering System as UNS S17400, is one of the most popular precipitation-hardening grades available in the market today. 

This material is classified as a precipitation-hardening martensitic stainless steel. The name "17-4" comes from its nominal chemical composition: approximately 17% chromium and 4% nickel. The "PH" stands for precipitation hardening, a heat treatment process that significantly increases yield strength. 

Unlike standard austenitic stainless steels (like 304 or 316), which rely primarily on cold working for strength, 17‑4 PH gains its mechanical properties through heat treatment. This makes it an incredibly versatile material for engineers. It offers a unique combination of high strength, good corrosion resistance (approaching that of 304 stainless), and excellent fabricability. 

At Nifty Alloys, we supply this grade primarily in the solution-annealed condition (Condition A), which is ready for fabrication or further heat treatment. Whether you need it for heavy-duty shafts or precision aerospace components, the 17‑4 PH / S17400 material provides a reliable balance of performance and longevity. 

UNS S17400 chemical composition

The performance of any alloy begins with its chemistry. For UNS S17400 round bar, the specific blend of elements is what allows it to be heat-treated to various hardness levels while maintaining corrosion resistance. 

The chemical makeup is strictly controlled to meet international standards such as ASTM A564 or AMS 5643. While exact percentages can vary slightly depending on the specific standard, the typical composition includes: 
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This precise chemistry ensures that the 17‑4 PH stainless steel bar you purchase from Nifty Alloys will respond predictably to heat treatment, delivering the mechanical properties specified in your engineering designs. 

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Equivalent grades of 17‑4PH / UNS S17400

Key Mechanical Properties and Benefits 

Engineers and procurement officers choose 17‑4 PH round bar because it solves a specific problem: the need for a material that is stronger than standard stainless steel but more corrosion-resistant than standard carbon steel. 

High Strength and Hardness 

The defining characteristic of this alloy is its ability to reach high strength levels through simple, low-temperature heat treatments. In the solution-annealed state (Condition A), it is relatively soft and machinable. However, after aging, the tensile strength can range from 135 ksi (930 MPa) to nearly 200 ksi (1379 MPa), depending on the temperature used. 

Corrosion Resistance 

Often, high strength comes at the cost of corrosion resistance. That is not the case here. Type 630 stainless steel offers corrosion resistance comparable to 304 stainless steel in most mild environments and is superior to the 400-series martensitic stainless steels. This makes it an excellent choice for food processing equipment, paper mill processing, and general chemical applications. 

Magnetic Behavior 

A frequent question we receive is regarding magnetism. Yes, unlike 316 or 304 grades, 17‑4 PH is magnetic in all conditions. This property can be useful in certain applications involving magnetic sorting or specific sensor requirements. 

Machinability and Fabrication 

While it is harder than standard austenitic grades, 17‑4 PH is generally considered to have fair machinability. It machines best in the solution-treated condition. It can also be welded easily compared to other precipitation-hardening grades, often without requiring pre-heating. 

Common Heat Treatment Conditions 

The versatility of 17‑4 PH / S17400 material lies in its heat treatment options. By varying the aging temperature, you can tailor the properties: 

• Condition H900: Aged at 900°F. This yields the highest strength and hardness but lower ductility.
• Condition H1025: Aged at 1025°F. Offers a balance of good strength with improved toughness.
• Condition H1150: Aged at 1150°F. This provides excellent ductility and impact strength, though tensile strength is reduced compared to H900.
• Condition H1150M: A double-aging process often used to soften the material for easier machining before final hardening.

When you order 17‑4PH round bar stock from us, specifying the condition is crucial to ensuring the material performs correctly in your application. 

Typical Applications of 17‑4 PH Round Bar 

Because of its unique blend of properties, 17‑4PH bar for shafts and valves is a standard requirement across several high-tech industries. It is the go-to material when a part must withstand high stress and corrosive environments simultaneously. 

Aerospace and Defense 

• In the aerospace sector, weight and strength are paramount. 17‑4 PH stainless steel for aerospace and petrochemical applications is common because it maintains high strength at temperatures up to 600°F (316°C). It is frequently used for aircraft structural parts, landing gear components, turbine blades, and missile fittings.

Oil, Gas, and Petrochemical 

• The petrochemical industry demands materials that resist sulfide stress cracking. UNS S17400 is widely used for gate valves, choke stems, pump shafts, and offshore platform components. Its resistance to corrosive slurries and high mechanical loads makes it ideal for downhole tooling and drilling equipment.

Marine Environments 

• While not as resistant to stagnant seawater as Grade 316, 17‑4 PH is excellent for marine applications where high strength is required, such as propeller shafts, fasteners, and keels, provided there is cathodic protection or regular maintenance.

Power Generation and Nuclear 

• The material is used in reactor components, turbine blades, and nuclear waste casks due to its stability and resistance to radiation damage in certain contexts.

General Engineering 

• You will also find this precipitation hardening stainless steel in food processing machinery (where high hardness prevents wear), pulp and paper mill equipment, and mechanical seals.

Available Sizes, Forms, and Supply Range at Nifty Alloys 

At Nifty Alloys, we understand that finding a stainless steel round bar supplier and exporter who can deliver the exact size and certification you need is challenging. We maintain a comprehensive inventory to support projects worldwide. 

Extensive Size Range 

We stock UNS S17400 round bar in a wide variety of diameters to suit different machining requirements. 

• Small Diameters: From 6mm (1/4") up to 25mm (1"). Ideal for fasteners, pins, and small valve stems.
• Medium Diameters: From 30mm up to 100mm (4"). Commonly used for pump shafts and gears.
• Large Diameters: From 110mm up to 400mm (16") and above. Used for heavy industrial components and large flanges.
• Forged Bars: For diameters exceeding standard rolled sizes, we can supply forged and rough-turned bars.

Cut-to-Length Service 

We know that shipping full random lengths isn't always efficient for your logistics or production. We offer precise cut-to-length services. Whether you need single billets for prototyping or thousands of pre-cut pieces for mass production, we process your order to minimize your scrap and machining time. 

Certification and Documentation 

Every bar we supply comes with full traceability. We provide Mill Test Certificates (MTC) in accordance with EN 10204 3.1. These documents verify the chemical composition, mechanical properties, and heat treatment condition of the material. If your project requires 3.2 certification (third-party inspection), we can arrange that with internationally recognized agencies like Lloyds, TUV, or DNV. 

Packaging for Global Export 

As a global exporter of stainless steel bars, we take packaging seriously. Materials are packed in high-quality wooden boxes or bundled with protective wrapping to prevent damage during sea or air transit. We ensure that your 17‑4 PH round bar arrives in pristine condition, ready for use. 

Why Choose Nifty Alloys as Your 17‑4 PH / S17400 Round Bar Supplier and Exporter? 

Sourcing special alloys from overseas requires trust. You need a partner who understands the technical nuances of 17‑4 PH stainless steel bar and values the integrity of your supply chain. Here is why procurement teams worldwide rely on Nifty Alloys. 

1. Unwavering Commitment to Quality 

We do not compromise on material quality. Our 17‑4 PH / S17400 material is sourced from reputable mills that meet strict international standards (ASTM, AMS, ASME). We verify every batch to ensure it meets the high strength corrosion resistant stainless steel specifications you ordered. 

2. Global Logistics Expertise 

Shipping heavy steel bars across borders can be complex. We have extensive experience in export logistics, handling all necessary documentation, customs clearance support, and freight arrangements. Whether you are in the Middle East, Europe, Asia, or the Americas, we deliver to your doorstep or nearest port efficiently. 

3. Technical Support and Responsiveness 

We are not just salespeople; we are technical partners. If you are unsure whether you need Condition A or Condition H1150, our team can guide you based on your application. We pride ourselves on rapid response times—when you send an enquiry, you get a quick, clear, and competitive quote. 

4. Comprehensive Inventory 

We aim to be your single-source solution. Beyond 17‑4 PH, we stock a vast range of stainless steels, nickel alloys, and special metals. This allows you to consolidate your purchasing orders, saving time and administrative costs. You can view our full range by visiting our stainless steel round bar product page. 

5. Transparency and Trust 

We believe in building long-term relationships. Our Mill Test Reports are genuine, our timelines are realistic, and our communication is transparent. When you choose Nifty Alloys, you choose a partner dedicated to your project's success. 

For more insights on material selection, you can browse our alloy steel and stainless steel blogs. 

Frequently Asked Questions (FAQ) 

Here are answers to the most common questions we receive from engineers and buyers regarding 17‑4PH round bar stock. 

Is 17‑4PH stainless steel magnetic? 

Yes, 17‑4PH (UNS S17400) is magnetic in all heat-treated conditions. This distinguishes it from the 300-series austenitic stainless steels (like 304 and 316), which are generally non-magnetic. If your application requires a non-magnetic material, 17‑4PH is likely not the correct choice. 

What is the difference between 17‑4PH and 316 stainless steel? 

The main difference lies in strength and magnetism. 17‑4PH is significantly stronger and harder than 316 stainless steel, making it better for high-stress parts. However, 316 has slightly superior corrosion resistance, especially in chloride environments, and is non-magnetic. For a deeper dive, check out our article on 17‑4PH vs 316 stainless steel. 

Can 17‑4PH be welded? 

Yes, 17‑4PH has excellent weldability compared to other precipitation-hardening stainless steels. It can be welded using common fusion and resistance methods. Unlike many high-strength alloys, pre-heating is not usually required, although post-weld heat treatment is recommended to achieve uniform properties across the weld zone. 

Which heat treatment condition should I choose? 

This depends on your application's priority. If you need maximum strength and hardness, choose Condition H900. If you need better ductility and impact resistance to prevent cracking under shock loads, choose Condition H1150. Most stock is supplied in Condition A (solution annealed) so you can machine it first and heat treat it later. 

What does "precipitation hardening" mean? 

Precipitation hardening is a heat treatment technique used to increase the yield strength of malleable materials. In 17‑4PH, it involves heating the steel to a specific temperature (aging), which causes copper precipitates to form within the alloy's microstructure. These precipitates block dislocation movement, significantly strengthening the metal. 

Is UNS S17400 the same as Type 630? 

Yes, they are the same material. Type 630 is the common AISI (American Iron and Steel Institute) designation, while UNS S17400 is the Unified Numbering System designation. Both refer to the same 17Cr-4Ni precipitation-hardening stainless steel chemistry and properties. 

Conclusion 

17‑4PH / S17400 round bar is a powerhouse material that bridges the gap between the corrosion resistance of stainless steel and the high strength of heat-treatable alloys. Its versatility makes it indispensable in aerospace, marine, and energy sectors.When you need a reliable global exporter of stainless steel bars who can provide certified materials, precise cutting, and expert logistics, look no further than Nifty Alloys. We ensure that your procurement process is smooth, compliant, and efficient.