Introduction to Stainless Steel Types
Stainless steel comes in several varieties, each designed for specific uses based on its properties. Choosing the right type can often feel like selecting the perfect tool for the job—precision matters.
Austenitic Stainless Steel: This is the go-to for industries that need top-notch corrosion resistance, like food processing and healthcare. Grades like 304 and 316 are popular for their durability and the fact they stay tough, even when it gets really cold. Plus, they’re non-magnetic, which adds to their versatility in applications where magnetism could be an issue.
Ferritic Stainless Steel: Ferritic Stainless Steel, such as 430, may not steal the spotlight, but they’re reliable workhorses. Often used in kitchen appliances and automotive parts, they offer moderate corrosion resistance and are magnetic. If you’re working on a budget and don’t need the extreme resilience of austenitic steel, this type gets the job done without breaking the bank.
Martensitic Stainless Steel: When you need toughness and hardness, martensitic steel is your friend. Think tools, knives, or machinery parts. Grades like 410 and 420 don’t offer the same corrosion resistance as austenitic steel, but they make up for it with strength. You might imagine them as the tough, no-nonsense option—perfect for demanding tasks.
Duplex Stainless Steel: This is where things get interesting. Duplex steel, such as 2205, combines the best of both austenitic and ferritic structures. It’s like having the strength of a bodybuilder with the agility of a gymnast. Ideal for oil refineries and marine environments, this steel excels in harsh conditions.
Precipitation-Hardening Stainless Steel: For industries where strength and precision are paramount, PH grades like 17-4 PH step in. Aerospace and chemical processing sectors rely on this type because it offers high strength while still maintaining excellent corrosion resistance. You could think of it as the steel that doesn’t compromise—offering both power and finesse.
These Values Are Not Absolute
Each of these properties—density, tensile strength, hardness, and melting point—can fluctuate based on multiple factors:
- Alloy Composition: The addition of various elements (e.g., chromium, nickel, molybdenum) changes the overall properties of the steel.
- Manufacturing Processes: Processes like annealing, cold working, and heat treatment can strengthen, soften, or otherwise alter the steel’s properties.
- Environmental Conditions: Temperature, pressure, and exposure to certain chemicals during manufacturing can affect the final material properties.
- Batch Variations: Even within the same grade of steel, different production batches may show slight variations due to differences in raw materials or processing conditions.
In summary, while we can provide general ranges for these properties, the exact values can vary depending on many factors related to composition and processing.
Comparison Table for Different Types of Stainless Steel
| Stainless Steel Type | Stainless Steel Grade | Density (g/cm³) | Tensile Strength, Ultimate (MPa) | Hardness (HRB/HRC) | Melting Point (°C) | Magnetism | Corrosion Resistance |
|---|---|---|---|---|---|---|---|
| Austenitic | 201 Stainless Steel | 7.81 g/cm³ | 758 MPa | 87 HRB | 1399 – 1454 °C (2550 – 2649 °F) | Non-magnetic (may become slightly magnetic after processing). | Good, suitable for general use, but not as resistant as 304 and 316. |
| 202 Stainless Steel | 7.86 g/cm³ | 515 MPa | 80 HRB | 1400 – 1450 °C (2550 – 2640 °F) | Non-magnetic (may become slightly magnetic after processing). | Similar to 201, suitable for general use. | |
| 301 Stainless Steel | 8.03 g/cm³ | 515 MPa | 85 HRB | 1399 – 1421 °C (2550 – 2590 °F) | Non-magnetic (may become slightly magnetic after processing). | Good, but slightly less than 304, suitable for springs, fasteners, etc. | |
| 304 Stainless Steel | 7.93 g/cm³ | 505 MPa | 70 HRB | 1400 – 1455 °C (2550 – 2651 °F) | Non-magnetic (may become slightly magnetic after processing). | Excellent, suitable for most environments, including food, chemical, and pharmaceutical industries. | |
| 304L Stainless Steel | 8.03 g/cm³ | 585 MPa | 80 HRB | 1399 – 1454 °C (2550 – 2649 °F) | Non-magnetic (may become slightly magnetic after processing). | Similar to 304, better resistance to intergranular corrosion, ideal for welding applications. | |
| 316 Stainless Steel | 7.99 g/cm³ | 579 MPa | 79 HRB | 1371 – 1399 °C (2500 – 2550 °F) | Non-magnetic. | Superior, especially in chloride-containing environments (e.g., marine environments). | |
| 316L Stainless Steel | 7.99 g/cm³ | 558 MPa | 79 HRB | 1371 – 1399 °C (2500 – 2550 °F) | Non-magnetic. | Similar to 316, with better resistance to intergranular corrosion. | |
| 321 Stainless Steel | 7.92 g/cm³ | 621 MPa | 80 HRB | 1371 – 1399 °C (2500 – 2550 °F) | Non-magnetic. | Similar to 304, with better oxidation resistance at high temperatures. | |
| 310 Stainless Steel | 7.84 g/cm³ | 617 MPa | 83 HRB | 1400 – 1455 °C (2550 – 2651 °F) | Non-magnetic. | Excellent, particularly in high-temperature environments. | |
| 904L Stainless Steel | 7.97 g/cm³ | 600 MPa | 90 HRB | 1300 – 1390 °C (2372 – 2534 °F) | Non-magnetic. | Very strong, especially in highly acidic environments, widely used in chemical and marine industries. | |
| 254 SMO Stainless Steel | 8.00 g/cm³ | 680 MPa | 96 HRB | 1320 – 1390 ℃ (2408 – 2534 °F) | Non-magnetic. | Extremely high, suitable for extreme corrosive environments, such as marine and chemical equipment. | |
| Ferritic | 409 Stainless Steel | 7.80 g/cm³ | 448 MPa | 75 HRB | 1425 – 1510 °C (2597 – 2750 °F) | Magnetic | Moderate, mainly used in automotive exhaust systems. |
| 430 Stainless Steel | 7.74 g/cm³ | 483 MPa | 85 HRB | 1425 – 1510 °C (2597 – 2750 °F) | Magnetic | Good, suitable for kitchen appliances and decorative applications. | |
| 434 Stainless Steel | 7.68 g/cm³ | 483 MPa | 85 HRB | 1426 – 1510 °C (2600 – 2750 °F) | Magnetic | Good, with added molybdenum for improved corrosion resistance, suitable for kitchen equipment and automotive exhausts. | |
| 439 Stainless Steel | 7.69 g/cm³ | 455 MPa | 74 HRB | 1426 – 1505 °C (2600 – 2471°F) | Magnetic | Good, with better weldability, suitable for automotive exhaust systems. | |
| 446 Stainless Steel | 7.70 g/cm³ | 550 MPa | 83 HRB | 1425 – 1510 °C (2597 – 2750 °F) | Magnetic | Excellent, particularly in high-temperature environments. | |
| Martensitic | 410 Stainless Steel | 7.65 g/cm³ | 450 MPa | 96 HRB | 1480 – 1530 °C (2700 – 2790 °F) | Magnetic | Moderate, suitable for knives, valves, and pumps. |
| 420 Stainless Steel | 7.73 g/cm³ | 586 MPa | 88 HRB | 1454 – 1510 °C (2649 – 2750 °F) | Magnetic | Good, often used in tools and medical instruments. | |
| 440 Stainless Steel | 7.80 g/cm³ | 760 MPa | 97 HRB | 1643 – 1753 °C (2500 – 2696 °F) | Magnetic | Moderate, with high hardness, suitable for knives and bearings. | |
| Duplex | 2205 Stainless Steel | 7.82 g/cm³ | 750 MPa | 95 HRB | 1385 – 1445 °C (2525 – 2630 °F) | Magnetic (due to the ferritic portion of its duplex structure). | Very high, especially strong against stress corrosion cracking, suitable for marine, oil, and chemical equipment. |
| 2507 Stainless Steel | 7.80 g/cm³ | 800 MPa | 108 HRB | 1410 – 1460 °C (2570 – 2660 °F) | Magnetic (due to the ferritic portion of its duplex structure). | Very high, suitable for extreme corrosive environments. | |
| 2101 Stainless Steel | 7.69 g/cm³ | 696 MPa | 106 HRB | 1385 – 1443 °C (2525 – 2630 °F) | Magnetic (due to the ferritic portion of its duplex structure). | Good, suitable for construction and light industry. | |
| Precipitation-Hardening | 17-4 PH Stainless Steel | 7.80 g/cm³ | 1350 MPa | 117 HRB | 1404 – 1440 °C (2560 – 2625 °F) | Magnetic | Excellent, widely used in aerospace and tooling industries. |
| 15-5 PH Stainless Steel | 7.78 g/cm³ | 1310 MPa | 108 HRB | 1404 – 1440 °C (2560 – 2625 °F) | Magnetic | Excellent, with higher toughness, suitable for aerospace and mechanical parts. |