Stainless Steel SUS304L
Introduction to Stainless Steel SUS304L: A Low-Carbon Austenitic Alloy
Stainless Steel SUS304L is a low-carbon version of SUS304, austenitic stainless steel known for its excellent corrosion resistance, good weldability, and formability. With a reduced carbon content (≤0.03%), SUS304L is specifically designed to provide improved weldability without the risk of carbide precipitation, making it an excellent choice for applications that require welding in corrosive environments. The alloy consists of 18–20% chromium and 8–10% nickel, offering enhanced oxidation and corrosion resistance in various environments, from food processing to chemical industries.
SUS304L’s properties make it an ideal material for components exposed to both high temperatures and aggressive environments. It can be easily formed, welded, and polished to meet a variety of industrial and commercial applications. CNC machining of SUS304L is relatively easy due to its excellent ductility and workability, but it requires proper tool selection and machining strategies to ensure precision. At Neway, CNC-machined SUS304L parts are produced to meet the highest accuracy, durability, and surface finish standards.
SUS304L Stainless Steel: Key Properties and Composition
SUS304L Stainless Steel Chemical Composition
Element | Composition (wt%) | Role/Impact |
|---|---|---|
Carbon (C) | ≤0.03% | Low carbon content reduces carbide precipitation, improving weldability. |
Manganese (Mn) | 2.00% | Improves toughness and strength, especially at lower temperatures. |
Chromium (Cr) | 18.0–20.0% | Provides resistance to corrosion, oxidation, and high-temperature environments. |
Nickel (Ni) | 8.0–10.5% | Enhances formability, ductility, and corrosion resistance, especially in acidic environments. |
Phosphorus (P) | ≤0.045% | Reduces sulfur contamination and enhances machinability. |
SUS304L Stainless Steel Physical Properties
Property | Value | Notes |
|---|---|---|
Density | 8.00 g/cm³ | Typical for austenitic stainless steels, ensuring durability. |
Melting Point | 1,400–1,450°C | Suitable for both cold and hot working, ideal for high-temperature applications. |
Thermal Conductivity | 16.2 W/m·K | Moderate heat dissipation, suitable for high-heat applications. |
Electrical Resistivity | 7.4×10⁻⁷ Ω·m | Low electrical conductivity, ideal for non-electrical applications. |
SUS304L Stainless Steel Mechanical Properties
Property | Value | Testing Standard/Condition |
|---|---|---|
Tensile Strength | 520–720 MPa | ASTM A240/A240M standard |
Yield Strength | 215 MPa | Suitable for structural applications |
Elongation (50mm gauge) | 40% | Excellent ductility, suitable for deep drawing and forming. |
Brinell Hardness | 170–200 HB | Achieved in a solution-treated state, offering moderate hardness. |
Machinability Rating | 60% (vs. 1212 steel at 100%) | Suitable for machining, with good machinability characteristics. |
Key Characteristics of SUS304L Stainless Steel: Benefits and Comparisons
SUS304L stainless steel is known for its excellent corrosion resistance, good strength, and ease of machinability. Below is a technical comparison highlighting its unique advantages over similar materials like SUS304 Stainless Steel, SUS316 Stainless Steel, and SUS430 Stainless Steel.
1. Corrosion Resistance
Unique Trait: SUS304L provides superior corrosion resistance in a variety of environments, especially those involving food, water, and chemicals.
Comparison:
vs. SUS304 Stainless Steel: Both alloys offer similar corrosion resistance, but SUS304L's low carbon content prevents carbide precipitation, improving weldability.
vs. SUS316 Stainless Steel: SUS316 offers better resistance to chloride-induced corrosion, but SUS304L performs well in most common corrosive environments.
vs. SUS430 Stainless Steel: SUS304L offers superior corrosion resistance compared to SUS430, especially in acidic environments.
2. Weldability and Formability
Unique Trait: The low carbon content in SUS304L significantly improves weldability, preventing weld-related defects such as carbide precipitation.
Comparison:
vs. SUS304 Stainless Steel: SUS304L has enhanced weldability due to its lower carbon content, making it ideal for welded assemblies.
vs. SUS316 Stainless Steel: SUS316 has better corrosion resistance but may require special welding techniques due to its higher carbon content.
vs. SUS430 Stainless Steel: SUS304L is easier to weld than SUS430, which has lower ductility and is more prone to cracking.
3. Strength and Durability
Unique Trait: While SUS304L offers good strength for most applications, it is not as strong as some other stainless steels, such as SUS440C or SUS630.
Comparison:
vs. SUS304 Stainless Steel: Both alloys offer similar strength, but SUS304L offers the added benefit of better weldability due to its lower carbon content.
vs. SUS316 Stainless Steel: SUS316 offers higher strength and corrosion resistance, especially in chloride-rich environments.
vs. SUS430 Stainless Steel: SUS304L is more ductile and offers better overall toughness than SUS430, which is more brittle.
4. Cost-Effectiveness
Unique Trait: SUS304L is cost-effective stainless steel for applications that require corrosion resistance and good weldability but do not demand the highest strength.
Comparison:
vs. SUS304 Stainless Steel: SUS304 and SUS304L are typically priced similarly, though SUS304L offers better weldability for a similar cost.
vs. SUS316 Stainless Steel: SUS304L is less expensive than SUS316, making it a more economical choice for less corrosive environments.
vs. SUS430 Stainless Steel: SUS304L is more expensive than SUS430 but offers superior corrosion resistance and weldability.
CNC Machining Challenges and Solutions for SUS304L Stainless Steel
Machining Challenges and Solutions
Challenge | Root Cause | Solution |
|---|---|---|
Work Hardening | Low work hardening rate | Use sharp carbide tools with TiN coatings for better cutting. |
Surface Roughness | Low carbon content and ductility | Optimize feed rates and use high-speed tools for smoother finishes. |
Tool Wear | Abrasive nature of stainless steel | Use high-performance tool coatings like TiAlN for reduced wear. |
Dimensional Inaccuracy | Stresses from machining | Perform stress-relief annealing to reduce dimensional variations and improve precision. |
Chip Control Issues | Long, stringy chips | Use high-pressure coolant and optimize tool geometry to break chips. |
Optimized Machining Strategies
Strategy | Implementation | Benefit |
|---|---|---|
High-Speed Machining | Spindle speed: 1,200–1,800 RPM | Increases productivity and reduces heat buildup. |
Climb Milling | Cutting in the direction of tool rotation | Improves surface finish (Ra 1.6–3.2 µm). |
Toolpath Optimization | Use trochoidal milling for deep pockets | Reduces cutting forces, minimizing part deflection. |
Stress-Relief Annealing | Preheat to 650°C for 1 hour per inch | Minimizes residual stress and improves machining accuracy. |
Cutting Parameters for SUS304L Stainless Steel
Operation | Tool Type | Spindle Speed (RPM) | Feed Rate (mm/rev) | Depth of Cut (mm) | Notes |
|---|---|---|---|---|---|
Rough Milling | 4-flute carbide end mill | 1,000–1,500 | 0.15–0.25 | 2.0–4.0 | Use coolant to prevent work hardening. |
Finish Milling | 2-flute carbide end mill | 1,500–2,000 | 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 | 500–700 | 0.20–0.30 | 1.5–3.0 | Dry machining is acceptable with air blast cooling. |
Surface Treatments for CNC Machined SUS304L 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 SUS304L Stainless Steel Parts
Automotive Industry
Exhaust Systems: SUS304L is commonly used for components requiring excellent corrosion resistance in harsh environments.
Chemical Processing
Pumps and Valves: SUS304L's resistance to corrosion and high temperatures makes it ideal for handling aggressive chemicals.
Food and Beverage Industry
Processing Equipment: The material’s excellent resistance to corrosion makes it perfect for food processing equipment.
Technical FAQs: CNC Machined SUS304L Stainless Steel Parts & Services
How does SUS304L compare to SUS304 in terms of welding performance?
What are the best surface treatments for enhancing the corrosion resistance of SUS304L?
Can SUS304L be used in marine environments, and how does it compare to SUS316?
What are the recommended machining parameters for achieving the best surface finish when machining SUS304L?
How does the machinability of SUS304L compare to other austenitic stainless steels?
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