Advanced 304/316 Stainless Steel Coil | Hairline Finish Toughness

Product Overview

Key Technical Specifications

Tensile & Bend Strength

The 304 stainless steel coil offers tensile strength of 520–750 MPa and yield strength of ≥290 MPa, making it ideal for applications requiring high ductility and moderate corrosion resistance, such as stainless steel coil tubing for food processing pipelines and architectural façades. Its austenitic structure ensures non-magnetic properties unless cold-worked, which enhances its suitability for components in HVAC systems.

The 316 stainless steel coil delivers superior tensile strength (500–680 MPa) and yield strength (≥175–210 MPa), optimized for harsh environments like marine equipment and chemical plants. The addition of 2–3% molybdenum enhances chloride resistance, making it a prime choice for stainless steel heat exchanger coil systems. Both grades exhibit excellent bend strength, supporting complex forming processes like deep drawing without cracking.

Weight Calculation

Calculate coil weight using:

$$\text{Weight (kg)}=\text{Thickness (mm)}\times \text{Width (m)}\times \text{Length (m)}\times \text{Density (g/cm³)}\times 0.001$$

Example: A 316 coil (2mm thick, 1.5m wide, 50m long) weighs:

$$2\times 1.5\times 50\times 7.98\times 0.001=11.97\text{kg}$$

This formula is critical for logistics planning, especially for projects requiring 1 3/4 stainless steel coil nails or large-scale industrial components.

Identification Methods

• Chemical Analysis: Confirm Cr (18–20%) and Ni (8–10.5%) for 304; Cr (16–18%), Ni (10–14%), and Mo (2–3%) for 316 via XRF testing.
• Magnetic Testing: 304 remains non-magnetic unless cold-worked; 316 is slightly magnetic post-processing.
• Spark Testing: 304 produces reddish sparks with minimal branching, while 316’s sparks are shorter due to molybdenum content.

Causes of Stainless Steel Corrosion

1. Chloride-Induced Pitting: Coastal environments or de-icing salts penetrate the passive Cr₂O₃ layer, forming micro-pits. 316’s molybdenum content reduces this risk by 30–50% compared to 304.
2. Galvanic Corrosion: Contact with carbon steel or copper in humid conditions accelerates oxidation. Use insulating materials to mitigate this in stainless steel heat exchanger coil installations.
3. Mechanical Abrasion: Scratches from handling tools expose raw metal to oxygen. Hairline finishes (Ra ≤0.5μm) reduce abrasion risks.
4. High-Temperature Oxidation: Prolonged exposure above 870°C degrades chromium’s oxide film. 316 outperforms 304 in thermal stability up to 925°C intermittently.
5. Organic Acid Accumulation: Food residues or industrial chemicals form corrosive films, particularly on unpolished surfaces.

Applications & Advantages

Versatile Industrial Use

• Architecture: Hairline finishes enhance façades while resisting urban pollution (e.g., elevator panels, signage).
• Energy & HVAC: Stainless steel heat exchanger coil systems leverage 316’s thermal stability (up to 870°C) and chloride resistance.
• Medical & Food: 304’s hygienic 2B/BA finishes (Ra ≤0.2μm) prevent bacterial growth in surgical tools and dairy tanks.

Functional Benefits

1. Self-Healing Oxide Layer: Chromium (≥18% in 304, ≥16% in 316) regenerates Cr₂O₃ to repair minor scratches.
2. Thermal Conductivity: 316’s thermal conductivity of 16.3 W/m·K ensures efficient heat distribution in exchangers.
3. Cost Efficiency: 304 reduces lifecycle costs by 20–30% compared to carbon steel, while 316 offers long-term savings in corrosive environments.

Why Choose Our Stainless Steel Coils?

1. Certified Quality: Sourced from TISCO/BAOSTEEL mills with ISO 9001, SGS, and RoHS compliance.
2. Custom Fabrication: Tailored slitting (3–2438mm), embossing, and polishing for stainless steel coil tubing projects.
3. Global Logistics: 7–15-day delivery via FOB/CIF with VCI anti-rust packaging.
4. Cost Efficiency: Direct mill partnerships reduce prices by 15–20% vs. competitors.
5. Technical Expertise: 20+ years in alloy selection, welding, and corrosion prevention consulting.