what is 347 stainless steel used for ？
Jul 07, 2025
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What Is 347 Stainless Steel?
347 stainless steel is a stabilized austenitic stainless steel alloyed with niobium (columbium), which enhances its resistance to intergranular corrosion-especially after welding or prolonged exposure to elevated temperatures (above 800°F / 425°C). It is chemically similar to 304 but offers better high-temperature strength and oxidation resistance, making it ideal for heat treatment, aerospace, and chemical environments.
UNS Number: S34700
Equivalent to: 1.4550 (EN), X6CrNiNb18-10 (DIN), ASTM A240 / A213 / A182
What Is 347 Stainless Steel Used For?
347 stainless steel is widely used in industries that require high-temperature strength, corrosion resistance, and excellent weldability. Common applications include:
Industrial & High-Temperature Uses:
Heat exchangers and superheaters
Boiler tubes
Refinery equipment
Furnace parts and radiant tubes
Chemical process piping
Aerospace & Aviation:
Jet engine components
Exhaust manifolds
Aircraft exhaust systems
Power Generation & Oil/Gas:
Turbine components
Reformer tubes
Pressure vessels and reactors
Fabricated Welded Structures:
Welded tanks and piping systems
Expansion joints
Flanges and fittings in high-temperature services
Chemical Composition
| Chemical Composition Limits | ||||||||||||
| Weight% | C | P | Si | Ni | Mn | S | Cr | Cb + Ta | Fe | Co | Mo | Cu |
| 347 | 0.08 max | 0.040 max | 1.00 max | 9-12 | 2.0 max | 0.030 max | 17-19 | 10 x C min | Bal | 1.00 max only AMS 5646 |
0.75 max | 0.75 max |
| 347H | 0.04-0.10 | 0.040 max | 1.00 max | 9-12 | 2.0 max | 0.030 max | 17-19 | 10 x C min | Bal | |||
Mechanical Properties
| Material | Yield Strength (ksi) | Tensile Strength (ksi) | % Elongation | Hardness HB |
| Alloy 347 Sheet (Sol Trtd) AMS 5512 |
25 | 70-105 | 40 | - |
| Alloy 347 Bar (Sol Trtd) AMS 5646 |
- | - | - | 255 max |
Performance advantages of 347 stainless steel
| Property | Description |
|---|---|
| High-temperature resistance | Maintains strength above 870°C (1600°F) |
| Stabilized against carbide formation | Niobium prevents intergranular corrosion after welding |
| Good mechanical strength | Comparable to 304 but better at elevated temps |
| Excellent weldability | Suitable for use in thick-walled or pressure vessels |
| Corrosion resistance | Good resistance to acids and atmospheric corrosion |
Need 347 Stainless Steel for Your High-Temperature Project?
We supply 347 stainless steel sheets, tubes, bars, and pipe fittings with:Certified mill test reports (MTRs),Cut-to-size and custom machining
Global delivery and technical support!
Product Forms of 347 Stainless Steel
Seamless and welded pipes (ASTM A312 / A213)
Sheets and plates (ASTM A240)
Bars and forgings (ASTM A182)
Wire and filler metals (AWS ER347 for welding)
Flanges, fittings, elbows, tees, reducers
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