Stainless Steel SUS304
Introduction to Stainless Steel SUS304: The Most Popular Stainless Steel Alloy
Stainless Steel SUS304 is one of the most widely used austenitic stainless steel, known for its excellent corrosion resistance, high tensile strength, and ease of fabrication. With a composition of approximately 18% chromium and 8% nickel, SUS304 offers outstanding resistance to oxidation and corrosion in a wide range of environments, including acidic and saline conditions. This makes it ideal for use in industries such as food processing, pharmaceuticals, chemical processing, and architectural applications.
Due to its excellent formability, SUS304 is commonly used to produce various industrial components, such as tanks, pipes, kitchen equipment, and automotive parts. In CNC machining, SUS304 can be easily processed to produce parts with high precision and minimal tool wear, making it a cost-effective option for large-scale production. CNC-machined SUS304 stainless steel parts are widely used across industries requiring both durability and aesthetic appeal.
SUS304 Stainless Steel: Key Properties and Composition
SUS304 Stainless Steel Chemical Composition
Element | Composition (wt%) | Role/Impact |
|---|---|---|
Carbon (C) | ≤0.08% | Low carbon content enhances weldability and prevents carbide precipitation. |
Manganese (Mn) | 2.0–2.5% | Increases strength and enhances corrosion resistance compared to other alloys. |
Chromium (Cr) | 18.0–20.0% | Provides excellent corrosion resistance and contributes to the alloy’s strength. |
Nickel (Ni) | 8.0–10.5% | Enhances ductility, toughness, and overall corrosion resistance. |
Nitrogen (N) | 0.10–0.16% | Improves strength and resistance to pitting corrosion. |
SUS304 Stainless Steel Physical Properties
Property | Value | Notes |
|---|---|---|
Density | 7.93 g/cm³ | Standard for austenitic stainless steels, providing reasonable weight. |
Melting Point | 1,400–1,450°C | Suitable for both cold working and high-temperature applications. |
Thermal Conductivity | 16.2 W/m·K | Moderate heat dissipation, suitable for general-use applications. |
Electrical Resistivity | 7.4×10⁻⁶ Ω·m | Low resistivity, ideal for structural and non-electrical applications. |
SUS304 Stainless Steel Mechanical Properties
Property | Value | Testing Standard/Condition |
|---|---|---|
Tensile Strength | 520–720 MPa | ASTM A240/A240M standard |
Yield Strength | 210 MPa | Suitable for structural applications requiring moderate strength. |
Elongation (50mm gauge) | 40% | High ductility for forming and welding applications. |
Brinell Hardness | 160 HB | Soft state, easy to machine and weld. |
Machinability Rating | 60% (vs. 1212 steel at 100%) | Excellent for turning, milling, and drilling in CNC machining. |
Key Characteristics of SUS304 Stainless Steel: Benefits and Comparisons
SUS304 stainless steel is commonly compared to other stainless steel alloys such as SUS303 Stainless Steel and SUS316 Stainless Steel. Below is a comparison that highlights the unique advantages of SUS304.
1. Optimized Corrosion Resistance
Unique Trait: SUS304 offers exceptional resistance to oxidation, making it ideal for use in environments with exposure to air, moisture, and mild chemicals.
Comparison:
vs. SUS303: SUS304 provides superior corrosion resistance compared to SUS303, especially in food processing or pharmaceutical environments.
vs. SUS316: SUS316 offers better resistance to chloride and other corrosive environments, making it ideal for marine applications. However, SUS304 is often sufficient for general industrial use.
2. Cost Efficiency
Unique Trait: While SUS304 is slightly more expensive than other grades like SUS201, its durability and corrosion resistance justify the cost for most industrial applications.
Comparison:
vs. SUS303: SUS304 is more expensive, but it provides superior corrosion resistance and is more durable, making it suitable for more demanding applications.
vs. SUS316: SUS316 is more expensive than SUS304, offering better resistance in harsh environments. SUS304 is the more affordable option when extreme corrosion resistance is not necessary.
3. Superior Formability and Weldability
Unique Trait: SUS304 has excellent formability and can be easily welded, which makes it highly versatile for fabrication into complex shapes and parts.
Comparison:
4. Dimensional Stability
Unique Trait: SUS304 offers excellent dimensional stability during CNC machining, making it ideal for high-precision components and structures.
Comparison:
5. Post-Processing Flexibility
Unique Trait: SUS304 can undergo a wide range of post-processing treatments, including passivation, electropolishing, and PVD coating, to further enhance its corrosion resistance and surface appearance.
Comparison:
vs. SUS303: SUS304’s higher resistance to corrosion means it requires fewer post-processing treatments than SUS303, which may need more extensive treatment for high-performance applications.
vs. SUS316: While SUS316 offers superior corrosion resistance, SUS304 is easier to process and typically requires less complex post-processing.
CNC Machining Challenges and Solutions for SUS304 Stainless Steel
Machining Challenges and Solutions
Challenge | Root Cause | Solution |
|---|---|---|
Work Hardening | High chromium and nickel content | Use carbide tools with TiN coatings to reduce friction and heat buildup. |
Surface Roughness | High ductility leading to "tearing" | Optimize feed rates and utilize climb milling for smoother finishes. |
Burr Formation | Softer material properties | Increase spindle speed and reduce feed rates during finishing operations. |
Dimensional Inaccuracy | Residual stresses from cold rolling | Perform stress-relief annealing at 650°C for dimensional stability. |
Chip Control Issues | Stringy, continuous chips | Use high-pressure coolant (7–10 bar) and implement chip breakers for better control. |
Optimized Machining Strategies
Strategy | Implementation | Benefit |
|---|---|---|
High-Speed Machining | Spindle speed: 900–1,200 RPM | Reduces heat buildup and improves tool life by 20%. |
Climb Milling | Directional cutting path for optimal surface finish | Achieves surface finishes of Ra 1.6–3.2 µm, improving part aesthetics. |
Toolpath Optimization | Use trochoidal milling for deep pockets | Reduces cutting forces by 30%, minimizing part deflection. |
Stress-Relief Annealing | Preheat to 650°C for 1 hour per inch | Minimizes dimensional variation to ±0.03 mm. |
Cutting Parameters for SUS304 Stainless Steel
Operation | Tool Type | Spindle Speed (RPM) | Feed Rate (mm/rev) | Depth of Cut (mm) | Notes |
|---|---|---|---|---|---|
Rough Milling | 4-flute carbide end mill | 900–1,200 | 0.15–0.25 | 2.0–4.0 | Use flood coolant to prevent work hardening. |
Finish Milling | 2-flute carbide end mill | 1,200–1,500 | 0.05–0.10 | 0.5–1.0 | Climb milling for smoother finishes (Ra 1.6–3.2 µm). |
Drilling | 135° split-point HSS drill | 600–800 | 0.10–0.15 | Full hole depth | Peck drilling for precise hole formation. |
Turning | CBN or coated carbide insert | 300–500 | 0.20–0.30 | 1.5–3.0 | Dry machining is acceptable with air blast cooling. |
Surface Treatments for CNC Machined SUS304 Stainless Steel Parts
Electroplating: Adds a corrosion-resistant metallic layer, extending part life in humid environments and improving strength.
Polishing: Enhances the surface finish, providing a smooth, shiny appearance ideal for visible components.
Brushing: Creates a satin or matte finish, masking minor surface defects and improving aesthetic quality for architectural components.
PVD Coating: Boosts wear resistance, increasing tool life and part longevity in high-contact environments.
Passivation: Creates a protective oxide layer, enhancing corrosion resistance in mild environments without altering dimensions.
Powder Coating: Offers high durability, UV resistance, and a smooth finish, ideal for outdoor and automotive parts.
Teflon Coating: Provides non-stick and chemical-resistant properties, ideal for food processing and chemical handling components.
Chrome Plating: Adds a shiny, durable finish that enhances corrosion resistance, commonly used in automotive and tooling applications.
Black Oxide: Provides a corrosion-resistant black finish, ideal for parts in low-corrosion environments like gears and fasteners.
Industry Applications of CNC Machined SUS304 Stainless Steel Parts
Automotive Industry
Engine Mounting Brackets: Cold-rolled SUS304 steel is ideal for automotive components that require high tensile strength and durability.
Industrial Machinery
Hydraulic Cylinders: Stress-relieved SUS304 steel maintains precise tolerances under high-pressure environments.
Construction and Structural
Building Frames: SUS304’s cost-effectiveness and strength make it the go-to material for construction beams and frames.
Technical FAQs: CNC Machined SUS304 Stainless Steel Parts & Services
How does SUS304 stainless steel compare to SUS303 in terms of machinability?
What are the primary industries that use CNC-machined SUS304 parts?
How does SUS304 perform in high-temperature applications compared to SUS316?
What are the best surface treatments for enhancing SUS304's corrosion resistance?
How can CNC machining optimize the production of SUS304 steel components?
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