Excellent application of precipitation hardening stainless steel (PH steel) in aviation, petroleum and medical industries
Precipitation hardening stainless steel (PH Stainless Steel)
Precipitation hardening stainless steel (PH stainless steel) is an alloy stainless steel that improves strength through aging treatment (precipitation hardening). It combines the characteristics of austenitic, martensitic and ferritic stainless steels, has good corrosion resistance, and can obtain high strength and hardness through heat treatment.
1. Classification of precipitation hardening stainless steel
According to the different metallographic structures, PH stainless steel is divided into three types:
Stainless Steel Classification
|
Classification |
Representative Grades |
Key Characteristics |
|---|---|---|
|
Martensitic |
17-4PH (S17400), 15-5PH (S15500) |
High strength and hardness; suitable for machinery manufacturing & aerospace |
|
Austenitic |
A286 (S66286), 17-10P |
Superior corrosion resistance; ideal for high-temperature & chemical industries |
|
Semi-Austenitic |
17-7PH (S17700), PH 15-7Mo (S15700) |
Excellent weldability; achieves high strength after heat treatment |
2. Typical precipitation hardening stainless steels and their properties
(1) Martensitic PH stainless steel
Precipitation Hardening Stainless Steel Properties
|
Grade (UNS) |
Chemical Composition (%) |
Yield Strength (MPa) |
Tensile Strength (MPa) |
Hardness (HRC) |
Primary Applications |
|---|---|---|---|---|---|
|
17-4PH (S17400) |
Cr:17, Ni:4, Cu:3, Nb:0.3 (balance Fe) |
≥ 1170 |
≥ 1310 |
38-44 |
Aerospace, Nuclear Industry, Precision Instruments |
|
15-5PH (S15500) |
Cr:15, Ni:5, Cu:3.5 (balance Fe) |
≥ 1100 |
≥ 1240 |
35-42 |
Aircraft Components, Petrochemical, Marine Engineering |
(2) Austenitic PH stainless steel
High-Temperature Alloy Properties
|
Grade (UNS) |
Chemical Composition (%) |
Yield Strength (MPa) |
Tensile Strength (MPa) |
Primary Applications |
|---|---|---|---|---|
|
A286 (S66286) |
Cr:15, Ni:25, Mo:1.3, Ti:2.1, Fe:bal |
≥ 415 |
≥ 895 |
High-Temp Components, Jet Engines, Turbine Blades |
(3) Semi-austenitic PH stainless steel
Precipitation Hardening Stainless Steel Comparison
|
Grade (UNS) |
Chemical Composition (%) |
Yield Strength (MPa) |
Tensile Strength (MPa) |
Hardness (HRC) |
Primary Applications |
|---|---|---|---|---|---|
|
17-7PH (S17700) |
Cr:17, Ni:7, Al:1 (balance Fe) |
≥ 1035 |
≥ 1240 |
38-44 |
Springs, Aerospace, Precision Instruments |
|
PH 15-7Mo (S15700) |
Cr:15, Ni:7, Mo:2 (balance Fe) |
≥ 1035 |
≥ 1310 |
35-43 |
Machinery Manufacturing, Food Industry |
3. Main features
High strength and hardness
After precipitation hardening treatment, the tensile strength can reach 1100-1500 MPa, which is 2-3 times higher than ordinary stainless steel (such as 304).
Good corrosion resistance
Better corrosion resistance than 400 series martensitic stainless steel, but slightly inferior to 300 series austenitic stainless steel (such as 316L).
Good weldability
17-4PH and 15-5PH can be heat treated after welding to maintain good strength and corrosion resistance.
Excellent dimensional stability
Small dimensional changes during heat treatment, suitable for precision mechanical parts.
Excellent wear resistance and fatigue resistance
Suitable for parts with high stress and impact loads, such as aviation landing gear, bearings, molds, etc.
4. Main application areas
🔹 Aerospace: engine parts, structural parts, fasteners
🔹 Oil and gas: valves, pipe fittings, drilling equipment
🔹 Medical devices: surgical instruments, implants (some PH stainless steel can be used in the medical industry)
🔹 Nuclear industry: radiation-resistant, high-strength structural parts
🔹 Automotive industry: racing parts, engine parts
🔹 Mold manufacturing: high-strength, high-wear-resistant molds
5. Heat treatment process of precipitation hardened stainless steel
The strength of precipitation hardened stainless steel is mainly achieved through aging treatment (Age Hardening).
Solution Treatment: Heat the material to 1050°C - 1100°C, cool it quickly, and form a single phase structure.
Aging Treatment: Heat to 480°C - 620°C for precipitation strengthening, so that the precipitated phase (such as Cu, Nb, Al) enhances the strength of the material.
Effect of different aging temperatures:
480°C - 510°C (H900 treatment) → Highest hardness (42-46 HRC), but lower toughness
550°C - 600°C (H1025 - H1150 treatment) → Slightly lower strength, but improved toughness and better corrosion resistance
6. Precipitation Hardening Stainless Steel vs. Other Stainless Steels
Stainless Steel Types Comparison
|
Property |
Precipitation Hardening (PH) Stainless Steels<br>e.g. 17-4PH, 15-5PH |
Austenitic Stainless Steels<br>e.g. 304, 316 |
Martensitic Stainless Steels<br>e.g. 410, 420 |
|---|---|---|---|
|
Strength (MPa) |
1100-1500 |
500-700 |
700-1000 |
|
Hardness (HRC) |
30-45 |
15-30 |
40-50 |
|
Corrosion Resistance |
Excellent |
Superior |
Moderate |
|
Weldability |
Excellent |
Superior |
Moderate |
|
Heat Treatment |
Precipitation Hardening |
Not Hardenable |
Quench & Temper Required |
|
Primary Applications |
Aerospace, Medical, Military |
Food Processing, Chemical, Marine |
Cutting Tools, Machinery Components |
If you need high strength + good corrosion resistance, choose precipitation hardening stainless steel (PH).
If corrosion resistance is the main consideration, choose austenitic stainless steel (such as 304, 316).
If you pursue high hardness and wear resistance, you can choose martensitic stainless steel (such as 420, 440C).
7. Precipitation hardened stainless steel is a high-strength, high-hardness and corrosion-resistant material, widely used in aviation, military, petroleum, automotive and medical industries.
Among them, 17-4PH is the most commonly used PH stainless steel, with high strength and corrosion resistance, suitable for most industrial applications.
Suitable for high strength + good corrosion resistance, but the corrosion resistance is slightly lower than 316L.
If you have specific material requirements (such as procurement, application analysis, etc.), welcome to consult!
