17-4 PH — Stainless Steel (SS) Grade Specification, Properties & Equivalents
17-4 PH stainless steel, also known as ASTM 630, is a martensitic precipitation-hardening stainless steel prized in India for its exceptional combination of high strength, moderate corrosion resistance, and good toughness. Fabricators and engineers across critical sectors like ae
17-4 PH stainless steel, also known as ASTM 630, is a martensitic precipitation-hardening stainless steel prized in India for its exceptional combination of high strength, moderate corrosion resistance, and good toughness. Fabricators and engineers across critical sectors like aerospace, oil and gas, and chemical processing rely on 17-4 PH for demanding components. Its unique properties allow it to achieve very high strength levels after a simple low-temperature heat treatment, making it a cost-effective and versatile choice for applications requiring superior mechanical performance. This grade's ability to be heat-treated to various property levels ensures it can be tailored to specific engineering requirements, driving innovation and reliability in Indian manufacturing.
Chemical Composition of 17-4 PH
17-4 PH Stainless Steel Chemistry
| Element | % Range |
| Iron (Fe) | Balance |
| Chromium (Cr) | 15.0 - 17.5 |
| Nickel (Ni) | 3.0 - 5.0 |
| Manganese (Mn) | Max 1.00 |
| Silicon (Si) | Max 1.00 |
| Molybdenum (Mo) | Trace |
| Phosphorus (P) | Max 0.070 |
| Sulfur (S) | Max 0.030 |
| Niobium (Nb) | 3.0 - 5.0 |
| Copper (Cu) | 3.0 - 5.0 |
Mechanical Properties of 17-4 PH
17-4 PH Stainless Steel Mechanical Properties (Condition H1150)
| Property | Value |
| Ultimate Tensile Strength (UTS) | 1100 MPa (160 ksi) |
| Yield Strength (YS) @ 0.2% Offset | 1000 MPa (145 ksi) |
| Elongation at Break | 10% |
| Hardness (Rockwell C) | 33 HRC |
| Density | 7.80 g/cm³ |
| Modulus of Elasticity | 190 GPa (27.5 x 10⁶ psi) |
17-4 PH Stainless Steel Available Forms in India
| Shape | Typical Sizes | Standard Length |
| Round Bars | 5 mm - 200 mm dia | 3-6 meters |
| Plates | 3 mm - 100 mm thk | Custom lengths up to 12 meters |
| Sheets | 0.5 mm - 3 mm thk | 1.2m x 2.4m, 1.2m x 3m |
| Seamless Tubes | 10 mm - 100 mm OD | Custom |
| Forgings | Custom Shapes | As per order |
17-4 PH Stainless Steel Real-world Applications
- Aerospace: Critical structural components, shafts, fasteners requiring high strength-to-weight ratio.
- Oil & Gas: Downhole drilling tools, shafts, pump components exposed to corrosive environments.
- Chemical Processing: Pump shafts, valves, and fittings needing corrosion resistance and strength.
- Medical Devices: Surgical instruments, implants where high strength and biocompatibility are crucial.
- Food Processing: Components requiring strength and good hygiene standards.
- Marine: Shafts, propellers, and fittings requiring resistance to saltwater corrosion.
- Automotive: High-performance engine components and drive shafts.
- General Engineering: Gears, couplings, and high-strength fasteners.
17-4 PH Stainless Steel Machinability & Weldability
Machining 17-4 PH stainless steel requires careful consideration due to its high strength, especially in precipitation-hardened conditions. It's generally machined in the solution-treated (Condition A) state before final heat treatment for optimal ease. Using sharp, rigid tooling and moderate cutting speeds is recommended. Carbide or high-speed steel tooling with adequate lubrication and coolant is essential to prevent excessive heat buildup and tool wear. For turning, speeds around 40-70 sfm and feeds of 0.005-0.010 in/rev are typical. Drilling and milling require slower speeds and feeds. Weldability of 17-4 PH is generally considered good, provided proper procedures are followed. It is typically welded in the solution-treated (Condition A) state and often requires post-weld heat treatment to regain full properties in the weld zone. Common welding methods include Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW). Use of matching filler metals like ER630 is recommended. Avoid welding in the fully aged conditions, as this can lead to cracking. Post-weld solution treatment followed by aging is crucial for optimal performance.
17-4 PH Stainless Steel Heat Treatment & Processing
The versatility of 17-4 PH stainless steel lies in its precipitation hardening heat treatment capabilities. The primary conditions are: Condition A (Solution Treated): Heated to 1020-1060°C and rapidly cooled (air or quench). This state offers good ductility and corrosion resistance, with a hardness typically around 28-32 HRC. It's the starting point for most fabrication and welding. Aging Treatment: After solution treatment, 17-4 PH is aged at controlled temperatures between 455°C and 565°C (850°F - 1050°F) to achieve desired strength and toughness properties. The most common aging temperature for high strength is Condition H900 (482°C/900°F) yielding hardness of ~45 HRC and UTS ~1700 MPa. For improved toughness and ductility, Condition H1150 (482°C/900°F for 4 hours, then 620°C/1150°F for 4 hours) provides ~33 HRC hardness and UTS ~1100 MPa. Other conditions like H1025, H1075, and H1150M offer intermediate properties. Careful control of aging temperature and time is critical for achieving the specific property profile required for 17-4 PH applications.
Sourcing 17-4 PH Stainless Steel in India
17-4 PH stainless steel is readily available from major Indian producers such as Jindal Stainless, SAIL (specialty products), and various smaller, specialized mills. Stockholders in major industrial hubs like Mumbai, Pune, and Chennai maintain significant inventories, ensuring swift delivery for most common forms like round bars and plates. Minimum Order Quantities (MOQs) can vary; typically, larger diameters or custom sections may require mill orders, while standard sizes are often available ex-stock. The price band for 17-4 PH (in Condition A, ready for hardening) generally ranges from INR 500/kg to INR 900/kg, depending on the form, quantity, and prevailing market conditions. Buyers can expect Mill Test Certificates (MTC) as per EN 10204 3.1 as standard, with 3.2 certifications available upon specific request, often at an additional cost. Procurement teams should always specify the desired condition (e.g., Condition A) and any required post-heat treatment certifications.
17-4 PH Stainless Steel International Equivalents
| Standard | Code |
| ASTM | A638 Grade 630 |
| AMS | 5643 |
| EN | 1.4542 / X5CrNiCuNb4-12-6 |
| JIS | SUS630 |
| UNS | S17400 |
| DIN | X5CrNiCuNb16-4 |
FAQs about 17-4 PH
What is 17-4 PH stainless steel and why is it used in India?
17-4 PH stainless steel (ASTM 630) is a high-strength, corrosion-resistant martensitic precipitation-hardening grade. In India, it's favored for aerospace, oil/gas, and chemical processing due to its excellent strength-to-weight ratio and ability to achieve high mechanical properties through simple heat treatment. Its reliability makes it a go-to material for demanding engineered components.
What are the common heat treatment conditions for 17-4 PH?
17-4 PH is supplied in the solution-treated Condition A, ready for fabrication. It's then aged at specific temperatures to achieve desired properties: H900 (highest strength, lower toughness), H1025, H1075, H1150 (good balance of strength/toughness), and H1150M (maximum toughness). The choice depends on the application's mechanical requirements.
What is the typical hardness and strength of 17-4 PH after heat treatment?
After aging, 17-4 PH exhibits a wide range of properties. Condition H900 can reach ~45 HRC hardness and ~1700 MPa UTS. Condition H1150 offers a balance with ~33 HRC hardness and ~1100 MPa UTS. These values allow tailoring the material to specific application needs, crucial for Indian engineering standards.
Where can I source 17-4 PH stainless steel in India?
17-4 PH stainless steel is accessible through major Indian producers like Jindal and SAIL, as well as numerous specialized stockholders. Key markets with readily available stock include Mumbai, Pune, and Chennai. Mill Test Certificates (MTC) are standard, ensuring quality compliance for Indian buyers.
Is 17-4 PH suitable for high-temperature applications?
17-4 PH is not ideal for sustained elevated temperatures above its aging temperature, as this can lead to over-aging and property degradation. Its strength significantly drops above 300°C (600°F). For high-temperature service, other stainless steel grades like 310 or Inconel alloys are typically recommended.
What are the key differences between 17-4 PH and 304 stainless steel?
17-4 PH is a martensitic precipitation-hardening grade offering significantly higher strength and hardness than austenitic 304. While 304 has better general corrosion resistance and formability, 17-4 PH excels in applications demanding superior mechanical performance, achieved through heat treatment.
Tags: grade, stainless steel (ss), 17-4 ph