Everything You Need to Know About 347 Stainless Steel Sheet
When choosing a material for high-temperature or corrosive environments, 347 stainless steel sheet is one of the top contenders. Designed...
When choosing a material for high-temperature or corrosive environments, 347 stainless steel sheet is one of the top contenders. Designed for durability, strength, and stability, this alloy has become a reliable choice across various industries.
In this guide, you’ll learn about the key properties, advantages, and uses of 347 stainless steel sheet. We’ll also compare it with similar grades to help you decide if it’s the right fit for your application.
What Is 347 Stainless Steel Sheet?
347 stainless steel is an austenitic stainless steel stabilized with niobium (also known as columbium). This stabilization prevents the formation of chromium carbide, which can lead to intergranular corrosion during or after welding.
This grade is essentially a modified version of 304 stainless steel but with added elements that make it ideal for high-heat environments and heavy-duty industrial applications. It’s especially suited for welding-heavy jobs or areas with repeated heating and cooling cycles.
Key Features of 347 Stainless Steel Sheet
1. High Heat Resistance
347 stainless steel sheet can withstand high temperatures without losing its strength. It performs well in environments where temperatures rise beyond 800°C (1470°F), making it perfect for thermal applications.
2. Resistance to Intergranular Corrosion
Thanks to the niobium content, this alloy resists corrosion that usually appears along grain boundaries after welding or exposure to high temperatures.
3. Good Mechanical Properties
It provides high tensile strength and yield strength, making it suitable for load-bearing applications. It also maintains excellent toughness even at cryogenic temperatures.
4. Excellent Weldability and Formability
The sheet can be easily welded and formed using conventional methods. It does not require post-weld annealing, saving time and cost during fabrication.
Chemical Composition
The chemical composition of 347 stainless steel is what gives it its corrosion and heat resistance. Here’s a typical breakdown:
| Element | Content (%) |
|---|---|
| Chromium (Cr) | 17.0 – 19.0 |
| Nickel (Ni) | 9.0 – 13.0 |
| Carbon (C) | Max 0.08 |
| Manganese (Mn) | Max 2.0 |
| Silicon (Si) | Max 1.0 |
| Phosphorus (P) | Max 0.045 |
| Sulfur (S) | Max 0.030 |
| Niobium (Cb + Ta) | 10xC min – 1.10 |
Mechanical Properties
Here are some typical mechanical values for 347 stainless steel sheet:
- Tensile Strength: ≥ 515 MPa
- Yield Strength (0.2% offset): ≥ 205 MPa
- Elongation: ≥ 40%
- Hardness (Brinell): ≤ 201 HB
These properties make it strong enough for structural components, especially where heat and pressure are constant factors.
Applications of 347 Stainless Steel Sheet
The combination of corrosion resistance, high strength, and heat stability makes 347 stainless steel sheet useful in several industries. Common applications include:
1. Aerospace and Aviation
Used in exhaust ducts, manifolds, and high-temperature sections of jet engines.
2. Chemical Processing
Ideal for chemical reactors, tanks, and pipelines where high temperatures and corrosive substances are present.
3. Petrochemical Industry
Used in refinery equipment, pressure vessels, and piping systems where high-pressure, high-temperature conditions exist.
4. Power Plants
Employed in boiler tubes, heat exchangers, and superheater elements that require excellent oxidation and creep resistance.
5. Food and Beverage Equipment
Used in steam-based food processing due to its hygienic, corrosion-resistant surface.
Available Sizes and Finishes
Manufacturers offer 347 stainless steel sheets in a variety of sizes, thicknesses, and surface finishes.
Common Thickness Range:
- 0.5 mm to 50 mm
Popular Finishes:
- 2B – Smooth, cold-rolled finish for general use
- BA – Bright annealed, highly reflective finish
- No. 4 – Brushed surface, often used in decorative or architectural projects
- Mirror – Highly polished for cosmetic or sanitary applications
Custom dimensions are also available upon request.
How It Compares to Other Grades
| Property | 304 SS | 321 SS | 347 SS |
|---|---|---|---|
| Heat Resistance | Moderate | High | Very High |
| Stabilizing Element | None | Titanium | Niobium |
| Weld Decay Resistance | Low | Moderate | Excellent |
| Corrosion Resistance | Good | Good | Excellent |
| Ideal Temperature Use | Up to 870°C | Up to 870°C | Above 870°C |
347 stainless steel sheet offers better performance than 304 and even 321 when it comes to stability at elevated temperatures and post-weld corrosion resistance.
Fabrication and Machining Tips
Working with 347 stainless steel sheet is similar to 304 or 316 grades:
- Cutting: Use laser, plasma, or water jet cutting for precision.
- Welding: Suitable for all standard welding methods (TIG, MIG, arc welding). No post-weld heat treatment required.
- Forming: Can be bent and formed using standard processes.
- Cleaning: Use mild detergents or warm water. Avoid chloride-based cleaners to prevent surface damage.
Why Choose 347 Stainless Steel Sheet?
If your application involves heat, pressure, or harsh chemicals, 347 stainless steel sheet is a dependable option. Its stability, strength, and corrosion resistance help reduce maintenance costs and improve product longevity.
Whether you’re in aerospace, petrochemicals, or power generation, this material provides peace of mind in demanding conditions.
Conclusion
The 347 stainless steel sheet offers a perfect balance of strength, corrosion resistance, and heat stability. It performs well under extreme conditions, making it a valuable material for a range of industrial applications. Easy to fabricate and resistant to intergranular corrosion, it’s a go-to solution for engineers and designers working in high-stress environments.
