17-4 stainless steel vs. 304: Key Differences
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When comparing 17-4PH stainless steel and 304 stainless steel, the choice of material depends on specific requirements. 17-4PH stainless steel offers higher strength and hardness, while 304 stainless steel provides better ductility, machinability, corrosion resistance, and lower cost. This article compares the two types of stainless steel to help you choose between 17-4PH and 304 stainless steel for your project.
What is 304 stainless steel?
304 stainless steel is the most common austenitic grade, known as "18/8" due to its composition of at least 18% chromium and 8% nickel, offering excellent corrosion resistance, formability, and aesthetic appeal, making it ideal for kitchenware, food processing, architectural trim, and general industrial uses. It's a versatile, non-magnetic alloy that balances strength, durability, and cost-effectiveness for a wide range of everyday applications.
What is 17-4 PH stainless steel?
17-4 PH stainless steel (UNS S17400) is a commonly used martensitic precipitation-hardening alloy that exhibits excellent high strength, high hardness, and good corrosion resistance. High performance is achieved after a simple heat treatment (aging), making it ideal for high-performance components in aerospace, oil and gas, and industrial applications. "17-4" indicates its approximate chromium content of 17% and nickel content of 4%, while "PH" stands for precipitation hardening, a process that significantly improves its mechanical properties without causing significant deformation.
304 vs. 17-4PH stainless steels : compositions
| Element | 17-4ph Stainless Steel | 304 Stainless Steel |
|---|---|---|
| Chromium | ~15% | Higher than 18% |
| Nickel | 4% | ~8-10% |
| Copper | Present | Absent |
304 vs. 17-4PH stainless steels : Chemical Composition
Grade 304 and 17-4 mainly differ in the proportion of the two elements. Those include chromium and nickel. The 304 grade consists of 18% chromium and 8% nickel. On the other hand, 17-4 stainless steel has lower chromium (17%) and nickel (4%) content.
| Element (%) | 17-4 PH (S17400) | 304 (S30400) |
| Chromium (Cr) | 15.0–17.5 | 18.0–20.0 |
| Nickel (Ni) | 3.0–5.0 | 8.0–10.5 |
| Carbon (C) | ≤0.07 | ≤0.08 |
| Manganese (Mn) | ≤1.0 | ≤2.0 |
| Silicon (Si) | ≤1.0 | ≤1.0 |
| Phosphorus (P) | ≤0.04 | ≤0.045 |
| Sulfur (S) | ≤0.03 | ≤0.03 |
| Copper (Cu) | 3.0–5.0 | – |
| Niobium + Tantalum (Nb+Ta) | 0.15–0.45 | – |
| Nitrogen (N) | – | ≤0.10 |
304 vs. 17-4PH stainless steels :Mechanical properties
| Property | 17-4 PH (H900) | 304 (Annealed) |
| Tensile Strength | 1310 MPa | 515–580 MPa |
| Yield Strength | 1170 MPa | 205–230 MPa |
| Hardness | HRC 40–44 | HB ≤201 / HRB ≤90 |
| Elongation | 10–16% | ≥40% |
| Elastic Modulus | 210 GPa | 193 GPa |
304 vs. 17-4PH Stainless Steels: Corrosion Resistance
304 (PREN ≈ 23–26) offers good general corrosion resistance in mild environments, but 17-4PH (PREN ≈ 24–30) has slightly better pitting resistance due to higher chromium and copper content, though both are less resistant to chlorides than 316 stainless steel.
| Property | 17-4 PH Stainless Steel | 304 Stainless Steel |
|---|---|---|
| Corrosion Resistance | Good up to 600°F (316°C) | Excellent in various environments |
| Pitting and Crevice Corrosion | More resistant to chloride-induced stress corrosion | Prone to pitting in warm chloride environments |
304 vs. 17-4PH Stainless Steels: Hardness
304 stainless steel in annealed condition has a typical hardness of ≤ 90 HRB (≈ 200 HV), while 17-4PH (peak-aged H900) reaches 38 HRC (≈ 380 HV), making it significantly harder and more wear-resistant.
304 vs. 17-4PH Stainless Steels: Heat Treatment
304 is non-hardenable by heat treatment and is used in the annealed state; 17-4PH requires a two-step process-solution annealing at 1040–1065 °C followed by aging at 482–621 °C (e.g., H900 at 482 °C×1 h)-to develop high strength and hardness.
304 vs. 17-4PH Stainless Steels: Applications
304 is widely used for kitchen equipment, architectural structures, and food processing due to its formability and weldability; 17-4PH is chosen for aerospace components, surgical instruments, and high-stress industrial parts where high strength (tensile ≥ 1310 MPa) and moderate corrosion resistance are required.
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.Email: info@gneestainless.com
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.
Click here to view our complete range of precipitation-hardening alloys: PH Alloys.
