what is difference between 15-5ph and 17-4ph ？
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Stainless steel is a popular choice for various industrial applications because of its strength, toughness and corrosion resistance properties. Two of the industry's most commonly used types of stainless steel alloys are 15-5 PH and 17-4 PH. Both of these alloys are precipitation-hardening grades that offer unique properties. In this blog post, we will compare these alloys to help you decide which would be better for your specific application.
What is 17-4PH material?
17-4PH stainless steel is a martensitic precipitation-hardening stainless steel. It contains approximately 15-17.5% chromium and 3-5% nickel, as well as 3-5% copper. The name comes from its chemical composition, approximately 17% chromium and 4% nickel. SUS630 is the same as 17-4PH; both refer to the same grade.
What is 15-5ph material equivalent to?
15-5 PH stainless steel is very common grade used in aerospace parts. This grade is written as 1.4545 or 1.4548 or X5CrNiCuNb15-5 according to EN norm and it is written as UNS S15500 according to UNS norm. We can think that 15-5 PH stainless is a better version of 17-4 PH (630 - 1.4542) material.
15-5PH vs. 17-4PH Stainless Steel: Chemical Composition Comparison
| Element | 17-4 PH (%) | 15-5 PH (%) |
|---|---|---|
| Chromium (Cr) | 15.0 – 17.5 | 14.0 – 15.5 |
| Nickel (Ni) | 3.0 – 5.0 | 3.5 – 5.5 |
| Copper (Cu) | 3.0 – 5.0 | 2.5 – 4.5 |
| Niobium (Cb) | 0.15 – 0.45 | 0.15 – 0.45 |
| Carbon (C) | ≤ 0.07 | ≤ 0.07 |
| Iron (Fe) | Balance | Balance |
15-5PH vs. 17-4PH Stainless Steel: Mechanical and Physical Properties
| Property | 17-4 PH | 15-5 PH |
|---|---|---|
| Ultimate Tensile Strength | 1000–1300 MPa | 1100–1380 MPa |
| Yield Strength | 850–1100 MPa | 930–1170 MPa |
| Hardness (HRC) | 35–44 | 36–45 |
| Density | 7.75 g/cm³ | 7.78 g/cm³ |
| Max Service Temp. | ≈ 600 °C | ≈ 620 °C |
15-5PH vs 17-4PH Stainless Steel: Strength and Toughness
Both 15-5PH (UNS S15500) and 17-4PH (UNS S17400) are precipitation-hardening martensitic stainless steels. In the peak-aged condition (15-5PH H900 / 17-4PH H900), 15-5PH has a tensile strength of approximately 1170–1240 MPa, yield strength of 1035–1105 MPa, and elongation of 10–15 %; 17-4PH has a tensile strength of ≥ 1310 MPa, yield strength of ≥ 1170 MPa, and elongation of ≥ 10 %. Thus, 17-4PH has higher strength, but 15-5PH, due to optimized copper content, has slightly better toughness (impact energy ~10–20 J higher).
15-5PH vs 17-4PH Stainless Steel: Corrosion Resistance
Both have similar chromium contents (15-5PH ~14.5–16.5 %, 17-4PH ~16–18 %) and PREN values of approximately 24–30, providing comparable corrosion resistance in atmospheric, fresh water, and mild acid environments. However, 17-4PH, with slightly higher chromium, performs better in oxidizing acids, while 15-5PH, due to copper micro-alloying, has slightly better corrosion resistance in reducing acids (e.g., dilute sulfuric acid), with overall differences being small.
15-5PH vs 17-4PH Stainless Steel: Heat Treatment
Both use a "solution annealing (1040–1065 °C water quenching) + aging" process, but with different aging parameters: 15-5PH commonly uses H900 (482 °C×1 h) or H1025 (552 °C×4 h), while 17-4PH uses H900 (482 °C×1 h) or H1150 (621 °C×4 h). Due to more uniform copper precipitate phases, 15-5PH has a faster aging response and requires a slightly lower temperature to achieve the same strength.
15-5PH vs 17-4PH Stainless Steel: Cost and Supply
15-5PH, due to its copper content and more complex production process, has raw material costs approximately 8–12 % higher than 17-4PH. In terms of market supply, 17-4PH is more common (accounting for about 60–70 % of the precipitation-hardening stainless steel market share), while 15-5PH is mostly produced on a customized basis, with a lead time 2–4 weeks longer.
What is the difference between 17-4ph and 304 stainless steel?
17-4 PH is a high-strength precipitation-hardening stainless steel, with strength and hardness far exceeding that of 304 stainless steel, making it ideal for demanding structural components. 304, on the other hand, is a versatile austenitic stainless steel widely used in the food and construction industries.
The main difference between the two lies in the higher strength achievable through heat treatment in 17-4 PH, while 304 is known for its general durability and corrosion resistance. However, 17-4 PH is susceptible to chloride stress corrosion cracking.
GNEE is a trusted supplier of precipitation-hardening stainless steel and specialty alloys in China. We supply 17-4 PH, 15-5 PH, and 17-7 PH alloys in various forms including bars, plates, profiles, and forgings. All products are sourced from certified steel mills and undergo rigorous chemical composition and mechanical property testing to ensure reliable quality.
Whether you are in the aerospace, oil and gas, marine engineering, or defense industry, we ensure that every batch of our products meets international standards and your specific application requirements.
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