Material Science Guide — Comprehensive Differences between 201 and 304 Stainless Steel
1.Name & Standard
| Category | 201 steel | 304 steel |
| Common Name | 201 type austenitic stainless steel, low nickel stainless steel | 304 austenitic stainless steel, 18-8 stainless steel (named after containing about 18% Cr and 8% Ni) |
Implementation Standard | Chinese GB/T20878-2007 'Stainless Steel and Heat Resistant Steel Grades and Chemical Composition', American ASTM A240/A240M | Chinese GB/T20878-2007 and American ASTM A240/A240M (globally recognized mainstream standards) |
| Core identifier | National standard grade: 1Cr17Mn6Ni5N; American standard grade: S20100 | National standard grade; 06Cr19Ni10; American standard grade: S30400 (most common, S30403 (low-carbon version)) |
2. Forms (Common Finished‑Product Shapes)
Both grades can be processed into various shapes via rolling, forging and other forming processes with no fundamental difference. Common forms are listed below:
- Plate & Sheet: Cold‑rolled sheet (thickness: 0.3‑6 mm, smooth surface, for decoration and equipment housings); Hot‑rolled plate (thickness: 3‑100 mm, rough surface, for structural parts and thick‑wall vessels).
- Pipe & Tube: Seamless tube (for high‑pressure pipelines and mechanical components); Welded tube (for decorative tubing and fluid‑transport pipelines).
- Profile: Angle steel, channel steel, square bar (for frames and support brackets).
- Wire / Rod: Used for woven mesh and fasteners (screws, nuts).
3. Material (Core Composition & Performance)
Differences in material composition are the root cause of all property gaps. The key lies in the content of Chromium (Cr), Nickel (Ni) and Manganese (Mn), which directly determine critical properties such as corrosion resistance and mechanical strength.
| Performance dimension | 201 steel | 304 steel |
| Core chemical components | Cr: 16% -18% (ensuring basic corrosion resistance) Ni: 3.5% -5.5% (low nickel) Mn: 5.5% -7.5% (high manganese, replacing some nickel) Containing N (nitrogen) to enhance strength | Cr: 18% -20% (higher chromium content, stronger corrosion resistance) Ni: 8% -10.5% (high nickel, ensuring austenite stability and corrosion resistance) Mn: ≤ 2% (low manganese) Does not contain N (or extremely low) |
| Mechanical properties | Tensile strength: ≥ 630MPa, high hardness (HV ≈ 280-320), good elasticity but slightly poor plasticity | Tensile strength: ≥ 515MPa, low hardness (HV ≈ 150-200), excellent plasticity, easy to process (bending, stretching) |
| Corrosion resistance | Only 'weakly corrosion-resistant': can withstand dry environments and neutral water, but is easily corroded by saltwater (such as seawater, kitchen soy sauce) and acidic solutions (vinegar, cleaning agents), and is prone to rusting after long-term use | Excellent corrosion resistance: able to withstand humid environments, neutral/weak acidic solutions, and slight saltwater, not easy to rust in daily environments (kitchen, bathroom), and meets food contact level standards |
| Magnetism | Some parts have weak magnetism (due to the possibility of austenite transforming into martensite during processing, such as after cold rolling) | Non magnetic (pure austenitic structure, also essentially non-magnetic after processing) |
4. Applications (Difference in Usage Scenarios)
201 Stainless Steel: Mid‑to‑low‑end scenarios with non‑critical corrosion‑resistance requirements
- Decoration: Stainless‑steel security grilles, guardrails, elevator door casings, billboard frames, lamp supports.
- Industrial auxiliary parts: Ordinary equipment housings, pipelines free of corrosive media, storage racks.
- Low‑cost daily goods: Non‑food‑contact kitchenware (e.g. spatula handles), waste‑bins, clothes‑drying racks.
304 Stainless Steel: Mid‑to‑high‑end scenarios requiring critical corrosion resistance & food‑safe performance
- Food‑contact fields: Stainless‑steel tableware (bowls, plates, cutlery), vacuum flasks, food‑processing equipment (conveyor belts, storage tanks), outer shells of water‑purifier cartridges.
- Household core components: Kitchen sinks, bathroom shelves, water‑heater inner tanks, washing‑machine drums.
- Critical industrial parts: Chemical equipment (pipelines carrying mildly corrosive fluids), medical‑surgical instruments, high‑grade exterior curtain‑walls.
5. Advantages (Respective Core Strengths)
Advantages of 201 Stainless Steel
- Low cost: Its nickel content is roughly half that of 304 stainless steel. Raw‑material costs are low, and finished‑product prices are 30%‑50% lower than 304.
- High strength: Elevated manganese and nitrogen improve hardness and tensile strength, suitable for applications requiring high rigidity (security grilles, guardrails).
- High processing efficiency: High hardness reduces deformation during cutting and welding, ideal for mass‑produced decorative structural components.
Advantages of 304 Stainless Steel
- Excellent corrosion resistance: Barely rusts under normal ambient conditions with minimal maintenance. Its service life is 2‑3 times longer than 201 steel.
- High safety level: Complies with GB 4806.9‑2016 National Food Safety Standard – Metal Materials and Articles for Food Contact. No harmful substances leach out; safe for direct food contact.
- Good workability: Outstanding plasticity enables complex forming operations (deep‑drawing for vacuum‑flask shells, one‑piece bending for sinks) with stable post‑fabrication performance.
- Wide‑ranging versatility: Referred to as the “all‑purpose stainless‑steel grade”, it covers household, industrial, food‑processing and medical‑device applications.
6. Disadvantages (Respective Limitations)
Drawbacks of 201 Stainless Steel
- Poor corrosion resistance (major weakness): Rust spots may emerge within 1‑2 years in humid, salty or acidic environments (coastal areas, kitchens), damaging appearance and shortening service life.
- Low food‑safety suitability: Low nickel and high‑manganese content carries potential manganese‑leaching risks with long‑term food contact. It fails food‑contact standards and must never be used in food‑related applications.
- Limited plasticity: High hardness makes cracking likely during bending or deep‑drawing; complex shapes (e.g. vacuum‑flask inner liners) cannot be manufactured.
- Short service life: Susceptible to corrosion, its average lifespan is only 3‑5 years (even shorter outdoors), bringing high replacement costs.
Drawbacks of 304 Stainless Steel
- High cost: Nickel is a precious metal. Its high nickel content pushes up raw‑material costs, and finished‑product prices are far above 201 steel; less economical for tight‑budget projects.
- Relatively lower mechanical strength: Softer than 201 steel. Thicker material must be used for security grilles or guardrails to maintain strength, further raising costs.
- Prone to processing deformation: Good plasticity with low hardness may cause distortion during cutting or welding without professional equipment and proper procedures.
7. Service‑Environment Suitability Comparison
| Environment Type | 201 steel adaptability | 304 steel adaptability | Core reason |
| Dry indoor environment | ★★★★☆ | ★★★★★ | 201 steel can be used normally, while 304 steel is more durable, but the difference is not significant |
| Wet/rainy environment | ★★☆☆☆ | ★★★★★ | 201 steel is easily corroded and rusted by water vapor, while 304 steel can withstand moisture |
| Kitchen | ★☆☆☆☆ | ★★★★★ | There is soy sauce and vinegar (acidic) in the kitchen, and shower gel (weakly alkaline) in the bathroom. 201 steel is prone to corrosion, while 304 steel can tolerate it |
| Seaside/high salt environment | ★☆☆☆☆ | ★★★☆☆ | Seawater contains high salt, and 201 steel may rust within a few days; 304 steel can withstand short-term corrosion, but 316 steel (higher corrosion resistance) is needed for long-term use |
| Acidic/chemical environment | ★☆☆☆☆ | ★★★☆☆ | 201 steel will be rapidly corroded by strong acids; 304 steel can withstand weak acidity (such as pH ≥ 4), and special stainless steel is required for strong acidity |
| Food contact scenarios | ★☆☆☆☆☆ (prohibited) | ★★★★★★ (Recommended) | 201 steel has a high manganese content and a risk of precipitation; 304 steel meets food grade standards |
8. Material‑Selection Recommendations
Prefer 201 Stainless Steel for:
- Dry, non‑food‑contact, short‑term‑use projects with limited budgets: Temporary decorative railings, indoor non‑load‑bearing racks, low‑cost clothes‑drying racks.
- High‑strength requirements with no corrosion‑resistance demand: Security grilles (requiring periodic paint maintenance), indoor‑enclosed mechanical housings.
Prefer 304 Stainless Steel for:
- All food‑contact scenarios: Regardless of budget, select 304 (tableware, vacuum flasks) to eliminate health hazards.
- Humid or corrosive environments: Kitchens, bathrooms and open‑air outdoor locations. 304 reduces rust‑related maintenance expenses.
- Long‑service‑life requirements: Core household components such as sinks and water‑heater tanks. Longer service life delivers better long‑term cost‑performance.
- High safety and aesthetic requirements: Medical instruments, premium exterior curtain‑walls, where 304 delivers superior stability and corrosion resistance.
Supplement: Quick Methods to Distinguish 201 and 304 Stainless Steel
- Check marking labels: Qualified products shall be stamped “304”, “SUS304” or “Food‑contact Grade”. 201‑grade items are usually unmarked or labelled “201”.
- Magnet test: 201 stainless steel may be weakly magnetic and attract a magnet; 304 stainless steel is generally non‑magnetic.
- Spot‑test reagent: Apply dedicated stainless‑steel identification liquid onto the metal surface. 304 shows no colour change, while 201 rapidly turns red due to corrosion reaction.
- Price comparison: Under identical specifications, 304 stainless steel costs at least 30% more than 201. Any suspiciously cheap “stainless‑steel” product is very likely 201 grade
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