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304

304 is the most widely used chromium-nickel austenitic stainless steel, with the national standard grade 06Cr19Ni10 and UNS S30400. It is non-magnetic and features outstanding ductility for general-purpose applications.

Typical Chemical Composition

  • Chromium (Cr): 18%–20% – provides rust resistance and corrosion protection
  • Nickel (Ni): 8%–11% – stabilizes austenitic microstructure and improves ductility & low-temperature toughness
  • Carbon (C): ≤0.08% – low carbon content reduces risk of intergranular corrosion
  • Balance iron with trace manganese and silicon impurities

Key Material Characteristics

  1. Excellent Corrosion Resistance A dense passive chromium oxide film forms on the surface, delivering reliable protection against atmospheric moisture, fresh water, weak acids and food-grade media. It offers stable anti-rust performance for wearable, medical, kitchen and automotive cosmetic components.
  2. Non-magnetic Austenitic Structure Non-magnetic under ambient temperature. Mild magnetic properties may occur after bending or stamping, making it suitable for audio and precision electronic decorative parts.
  3. Superior Plasticity & Formability High ductility enables bending, drawing and deep drawing. It is highly compatible with MIM, polishing, sandblasting and other surface finishing processes, ideal for miniature complex decorative and structural components.
  4. Excellent Low-Temperature Performance No brittle transition at low temperatures, making it a top choice for cryogenic service parts.
  5. Mechanical Strength Moderate strength in annealed condition. It cannot be hardened via quenching; hardness can only be slightly raised by cold working such as stamping and wire drawing. For high-strength, wear-resistant parts, 17-4PH or 440 martensitic stainless steels are preferred.
  6. Heat Resistance Continuous service temperature up to 870°C, with short-term heat resistance reaching 1000°C and good oxidation resistance.

Machining Compatibility (MIM Production Scenarios)

  1. Metal Injection Molding (MIM) 304 powder features favorable flowability and high sintered density after debinding and sintering. Perfect for miniature buckles, buttons, wearable bezels, medical tweezers and thin-walled irregular components, with low cracking risk thanks to high toughness.
  2. Wide Compatibility with Surface Treatments Supports mirror polishing, brushing, sandblasting, passivation and PVD coating with AF anti-fingerprint film, meeting cosmetic requirements for smart wearables, audio devices and automotive trims.
  3. Heat Treatment Limitations Not hardenable by quenching. Solution treatment is commonly applied to eliminate processing stress and restore corrosion resistance; no hardness improvement can be achieved through aging.

Advantages & Disadvantages

Advantages

  • Cost-effective general stainless steel with stable supply chains
  • Strong resistance to rust, weak acids and alkalis; food-safe and biocompatible
  • Easy to polish for premium cosmetic finishes for decorative parts
  • High toughness with low fracture risk, suitable for frequently opened small parts including buckles, watch bezels and earphone buttons

Disadvantages

  • Low hardness and poor wear resistance; not recommended for heavy-load or high-friction moving assemblies such as hinges and gears (17-4PH is preferred)
  • Prone to pitting corrosion in chloride-rich environments (seawater, heavy salt mist); switch to 316L for harsh corrosive conditions
  • Cannot be strengthened by heat treatment

Typical Applications (Matching Your Product Portfolio)

  1. Smart Wearables: Watch bezels, watch band buckles, decorative AI eyewear parts
  2. Audio Equipment: TWS earphone buttons, decorative components
  3. Automotive Parts: Car key ornaments
  4. Medical Devices: Medical tweezers, minimally invasive instruments under low mechanical loads
  5. General Hardware: Kitchen & bathroom fittings, precision cosmetic trims

Comparison of Similar Grades (304 / 304L / 316L)

  • 304: Standard general grade with balanced cost and performance for regular dry & wet environments
  • 304L: Extra-low carbon variant with superior resistance to intergranular corrosion after welding, widely used for piping and fluid connectors
  • 316L: Molybdenum-alloyed for enhanced salt spray and acid resistance, specified for medical implants and marine environments