ThePipingMart Blog Grades 17-7 PH Stainless Steel (UNS S17700) – Composition, Properties and Uses

17-7 PH Stainless Steel (UNS S17700) – Composition, Properties and Uses

17-7 PH Stainless Steel

Stainless steel is a widely used metal alloy due to its exceptional corrosion resistance, durability, and aesthetic appeal. One such variation of stainless steel is the 17-7 PH stainless steel, a precipitation-hardening steel that mildly undergoes corrosion. This high-performance alloy possesses excellent mechanical and physical properties, making it an ideal choice for various industrial applications. This blog aims to provide an in-depth understanding of 17-7 PH stainless steel and its uses.

What is 17-7 PH Stainless Steel?

17-7 PH stainless steel is a high-strength alloy with excellent corrosion resistance. Its unique composition includes aluminium, chromium, and nickel, giving it an impressive high strength and flexibility combination. As an expert in metallurgy, this alloy is commonly used in aerospace applications and other industries that require parts to withstand extreme stress and strain. If you’re looking for a material that can handle demanding environments and provide long-lasting durability, 17-7 PH stainless steel might be your solution.

17-7 PH Stainless Steel Composition

17-7 PH stainless steel is an austenitic-martensitic alloy that contains 17% chromium, 7% nickel, and 1.75% aluminium. This combination produces an alloy that can be processed through heat treatment to increase its strength and flexibility.

Element Content (%)
Chromium, Cr 16-18
Nickel, Ni 6.50 – 7.75
Manganese, Mn 1 max
Silicon, Si 1 max
Aluminum, Al 0.75 – 1.50
Carbon, C 0.09 max
Phosphorous, P 0.040 max
Sulfur, S 0.030 max
Iron, Fe Balance

17-7 PH Stainless Steel Mechanical Properties

The mechanical properties of 17-7 PH stainless steel make it distinctive from other alloys. It can achieve high strength through heat treatment while still maintaining its flexibility. After heat treatment, it has a minimum 1000MPa tensile strength, a minimum 10% elongation at break, and a minimum of 480 MPa yield strength. Additionally, 17-7 PH steel has good fatigue resistance, high corrosion fatigue strength, and excellent formability.

Properties Metric Imperial
Tensile strength 1170 MPa 170000 psi
Yield strength 965 MPa 140000 psi
Modulus of elasticity 204 GPa 29600 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Elongation at break 6% 6%
Hardness, Rockwell C 38 38

17-7 PH Stainless Steel Physical Properties

17-7 PH stainless steel has a low modulus of elasticity, a high tensile strength, and a density of 7.75 g/cm3. It has a high-temperature thermal expansion coefficient, making it suitable for use in applications with varying temperatures. It also has an excellent electrical conductive property, making it ideal for use in electrical components.

Properties Metric Imperial
Density 7.80 g/cm3 0.282 lb/in3

17-7 PH Stainless Steel Equivalent

AISI 631 AMS 5528 AMS 5529 AMS 5568 AMS 5644
AMS 5678 ASTM A313 (631) ASTM A564 (631) ASTM A579 (631) ASTM A693 (631)
ASTM A705 (631) DIN 1.4568 MIL S-25043 DIN 1.4568 AMS 5673
AMS 5824 ASME SA705 ASTM A579 (grade 62) MIL SPEC MIL-W-46078 SAE J217
SAE J467

17-7 PH Stainless Steel Thermal Properties

Properties Metric Imperial
Thermal conductivity 16.4 W/mK 114 BTU in/hr.ft2.°F
Thermal expansion co-efficient (@0.000-100°C/32-212°F) 11 µm/m°C 6.11 µm/m°C

17-7 PH Stainless Steel Uses

17-7 PH stainless steel is widely used in various industrial applications such as aerospace, medical equipment, and the automotive industry. In aerospace, it is commonly used in the aircraft landing gear assembly and the engine components. The medical industry uses 17-7 PH stainless steel for dental and surgical instruments. It is also used in engine valves, transmission components, and power generation equipment.

17-7 PH Stainless Steel Corrosion Resistance

17-7 PH stainless steel has excellent corrosion resistance in both the annealed and heat-treated states. This alloy is known to resist corrosion in atmospheric conditions, freshwater, and organic acids. However, it should not be used in environments containing chlorides and strong acids.

17-7 PH Stainless Steel Heat Treatment

17-7 PH stainless steel is designed to be heat-treated to improve its mechanical properties significantly. It can undergo a process known as precipitation hardening, which involves the steel being annealed and then rapidly cooled before reheating. This process results in stronger, more durable steel that withstands high-stress loads.

17-7 PH Stainless Steel Machining

Machining 17-7 PH stainless steel can be challenging due to its high strength. Cold working is the preferred technique because it strengthens the material as the operation continues and must be handled meticulously.

17-7 PH Stainless Steel Welding

17-7 PH stainless steel can be welded using standard welding techniques for stainless steel.

17-7 PH Density

17-7 PH density is a topic that has intrigued scientists and engineers for years. The density of this alloy is unique and can vary depending on a number of factors. The properties of 17-7 PH density have been studied in depth to understand how it can be used in various applications. It’s important to note that 17-7 PH density is not just a number. It is a key component in understanding this alloy’s physical and chemical makeup. The density of 17-7 PH is a testament to the complexity and versatility of this material and its potential to be used in a wide range of industries.


In conclusion, 17-7 PH stainless steel is a robust and versatile stainless steel alloy used in various industrial applications. Its unique mechanical and physical properties make it an ideal choice for high-strength, fatigue-resistant components. Precipitation hardening, heat treatment, and cold working are essential for enhancing the properties of this alloy. Additionally, 17-7 PH stainless steel demonstrates remarkable corrosion resistance, making it a popular choice in harsh environments.

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