Stainless steel refers to a chromium content of not less than 10.5% of the steel, with good corrosion resistance, high temperature, strength, beauty and easy to clean and other characteristics, common types of stainless steel 304/316/321/401/420/440/2205/2507 stainless steel, according to the composition can be divided into austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, duplex stainless steel, precipitation hardening stainless steel five categories.
Stainless Steel Chemical Composition Classification
Austenitic stainless steel Composition
- Characteristics: non-magnetic, high corrosion resistance, excellent formability and weldability.
- Common grades: 304, 316, 321, and so on.
Ferritic Stainless Steel Composition
- Characteristics: magnetic, medium corrosion resistance, good resistance to stress corrosion.
- Common grades: 430, 409, 439, and so on.
Martensitic stainless steel Composition
Characteristics: High hardness, high strength, can be strengthened by heat treatment, but weaker corrosion resistance.
Common grades: 410, 420, 440C, and so on.
Duplex stainless steel Composition
Characteristics: austenitic + ferrite duplex structure, high strength, resistance to chloride corrosion.
Common grades: 2205 (S31803), 2507 (S32750), and so on.
Precipitation-hardening stainless steel Composition
Characteristics: high strength and corrosion resistance through aging treatment.
Common grades: 17-4PH (630), 15-5PH, and so on.
Common Stainless Steel Grades in Detail
The composition of stainless steel determines its characteristics and application areas, so each type of stainless steel has its own characteristics and suitable application scenarios, and it is not necessarily true that higher grades are better. Wanzhi Group has compiled a list of popular stainless steel grades, compositions and properties, hoping to help you choose the most suitable stainless steel material.
Austenitic stainless steel
| Grade | Ingredients | Performance & Characteristics | Application Scenario |
| 304 | 18% Cr, 8% Ni | General purpose, acid and alkali resistant, non-magnetic, easy to process | Kitchenware, piping, building decoration |
| 304L | 18% Cr, 8% Ni, low carbon（≤0.03%） | Resistant to intergranular corrosion, better welding performance | Chemical equipment, welded structural parts |
| 316 | 16% Cr, 10% Ni, 2% Mo | Resistant to chloride corrosion (marine environment) | Ship fittings, seawater treatment equipment, medical equipment |
| 316L | low carbon 316（≤0.03% C） | Resistant to intergranular corrosion, suitable for welding (high temperature environment) | Nuclear industry, pharmaceutical equipment, marine engineering |
| 321 | 18% Cr, 10% Ni, +Ti | Resistant to high temperature oxidation(≤800°C) | Aircraft engine parts, heat exchangers |
Ferritic stainless steel
| Grade | Ingredients | Performance & Characteristics | Application Scenario |
| 430 | 16% Cr | Resistant to atmospheric corrosion, low cost, magnetic | Appliance panels, automotive trim, tableware |
| 409 | 11% Cr, +Ti | High temperature oxidation resistance, better fatigue resistance | Automobile exhaust pipes, mufflers, burners |
| 439 | 18% Cr, +Ti | Corrosion resistance better than 430, weldable | Water heater liner, solar collector panel |
Martensitic stainless steel
| Grade | Ingredients | Performance & Characteristics | Application Scenario |
| 410 | 12% Cr, 0.15% C | High hardness, abrasion resistance, weak corrosion resistance | Cutting tools, valve parts, pump shafts |
| 420 | 13% Cr, 0.3% C | High hardness, good polishability | Surgical instruments, tableware, molds |
| 440C | 17% Cr, 1% C, +Mo | Ultra-high hardness (HRC 58-60), wear-resistant | Bearings, precision tools, surgical blades |
Duplex stainless steel
| Grade | Ingredients | Performance & Characteristics | Application Scenario |
| 2205 | 22% Cr, 5% Ni, 3% Mo, 0.17% N | High strength (≈620 MPa), chlorine ion corrosion resistance | Offshore platforms, chemical tanks, desalination equipment |
| 2507 | 25% Cr, 7% Ni, 4% Mo, 0.3% N | Superb corrosion resistance (pitting resistance index ≥40) | Deep sea pipeline, sour oil and gas field equipment |
Precipitation-hardening stainless steel
| Grade | Ingredients | Performance & Characteristics | Application Scenario |
| 17-4PH | 17% Cr, 4% Ni, 4% Cu | High strength (≈1300 MPa), corrosion resistant | High strength (≈1300 MPa), corrosion resistant |
| 15-5PH | 15% Cr, 5% Ni, +Cu、Nb | High toughness, excellent fatigue resistance | Precision gears, springs, high-stress structural components |
Stainless Steel International Standard Comparison
Current. Popular international standards for stainless steel are the American AISI standard, the European EN standard, the Japanese JIS standard, and the Chinese GB standard. You can refer to the following table for the grade comparison of different standards!
| GB | AISI | EN | JIS |
| 06Cr19Ni10 | 304 | 1.4301 | SUS304 |
| 022Cr17Ni12Mo2 | 316L | 1.4404 | SUS316L |
| 10Cr17 | 430 | 1.4016 | SUS430 |
| 14Cr17Ni2 | 431 | 1.4057 | SUS431 |
How to Choose a Stainless Steel Grade?
After learning so much about the classification of stainless steel, how to quickly select the ideal type of stainless steel? Based on years of export experience, Wanzhi Group has some suggestions to help you get the most cost-effective stainless steel.
Corrosion resistance requirements:
- Normal environment (fresh water, atmosphere): 304, 430.
- Highly corrosive environment (seawater, chemical): 316, 2205.
Strength and hardness requirements:
- High hardness: martensitic (such as 440C), precipitation hardening type (17-4PH).
- High toughness: duplex stainless steel (2205).
Temperature conditions:
- High temperature (>500°C): 321, 309S.
- Low temperature (-196°C): 304L, 316L (austenitic low temperature toughness).
Cost budget:
- Economy type: 430, 304.
- High-end type: 316L, 2507.