Type 347 (UNS S34700/1.4550)
- Similar to SS 304 in properties.
- Excellent for heat resistance.
- Austenitic stainless steel.
- Non-magnetic when annealed.
- Cold temperature resistance.
- Better creep and stress than SS 304/L.
Description
The SS Type 347 is austenitic steel stabilized with columbium or tantalum for better temperature resistivity. It has many traits matching with the Type 304/L. Some manufacturers also use niobium, which offers excellent interangular resistance against corrosion when the steel is exposed to temperatures ranging from 800F to 1500F.
With better temperature and corrosion resistance, this steel can serve a wide range of applications. The steel is better suited for the [arts that are welded together and are not required to be annealed subsequently.
Common Names:
Other names of stainless steel 347 are AISI 347, UNS S34700.
Executive Standards:
- RR SABRe Edition 2
- DFARS Compliant
- ASME SA 269
- ASME SA 276
- UNS S34700
- ASTM A 269
- ASTM A 276
- ASTM A193
- AMS 5512
- AMS 5646
- EN 1.4550
- PWA-LCS
- S1000 / S-SPEC-1
- EN 10088-2: 1.4550
- EN 10088-3: 1.4550
- ASME SA-240M: Type 347H / UNS S34709, and Type 347H / UNS S34709
- ASTM A240/A240M: Type 347H / UNS S34709, and Type 347H / UNS S34709
- IS 6911: ISS 347; ISS 347H
- EN 10028-7 or PED 2014/68/EU: 1.4550
Chemical Properties:
| Elements | Content |
| Chromium | 17% to 19% |
| Nickel | 9% to 12% |
| Manganese | 2% |
| Nitrogen | 15% |
| Columbium/Tantalum/Niobium | 0.01% to 1% |
| Silicon | 0.75% |
| Carbon | 0.08% |
| Phosphorous | 0.045% |
| Sulfur | 0.03% |
| Iron | Balance |
Mechanical Properties:
| Property | Type 321 | Type 347 |
| Yield Strength, 0.2% Offset | 205 MPa (30,000 psi) | 205 MPa (30,000 psi) |
| Ultimate Tensile Strength, | 515 MPa (75,000 psi) | 515 MPa (75,000 psi) |
| Elongation in 2 inches (51mm) | 40% | 40% |
| Maximum hardness
|
217 (Brinell) 95 (RB) | 201 (Brinell) 92 (RB) |
Physical Properties:
The density of SS Type 347 is 7.96 g/cm3 (0.288 lb/in3).
Key Features:
- Its electric resistivity at 20C (68F) is 72 microhm-cm and magnetic permeability is 1.02 max when annealed.
- Thermal conductivity is between 20C to 100C (68F to 212F) is 16.3 W/m-K (Btu-in/hr-ft2-F).
- Electric resistivity @ 20C is 72 microhm-cm.
- Magnetic permeability is 1.02 max (annealed).
- Thermal conductivity (20C to 100C) is 16.3 W/m-K.
Product Forms Available:
- Strip
- Coil
- Wire
- Foil
Applications:
- Boiler casings
- Furnace heating elements
- Aircraft collector rings and exhaust stacks
- Heavy equipment (wall-welded)
- Collector rings
- Annealing box covers
- Cabin heaters
- Jet engine parts
- Tubing fasteners
- Expansion joints
- Metal bellows and hose
Possible Alternative Grades:
- Type 321/H – For better corrosion and temperature resistivity.
- Type 304/L – A mid-high temperature (@ 600C) environment is present only.
FAQs
- How does steel behave when exposed to cold forming?
SS 347 is very easy to form and draw and like most other austenitic steels its work hardens and requires annealing right after it severe forms
- How to harden SS 347 with heat treatment?
Type 347 is not going to harden by heat treatment. Only cold working works for this.
- How to weld SS347?
You can weld ss 347 by using standard fusion-resistance techniques. For the best results, you can use 347/348 electrodes or filler rods.
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