General Information
Chemical Composition
Physical Properties
Mechanical Properties
General Information
347 stainless steel has slightly improved corrosion resistance over type 321 stainless steel in strongly oxidizing environments. Type 347 is stabilized with columbium, it is preferable for aqueous and low temperature environments due to its good resistance to intergranular attack. Both 347 and 321 offer good resistance to polythionic acid stress corrosion cracking, encountered in oil refineries. The high temperature oxidation resistance of 347 is similar to that of 304 stainless steel. Useful to 1500°F.
Standard Inventory Specifications
- AMS 5512,
- AMS 5646,
- AMS 5680,
- ASME SA 240,
- ASTM A 269,
- ASTM A 479,
- ASTM A262 Practice E,
- MSRR 5632, PWA 300,
- PWA F17 LCS,
- UNS S34700,
- UNS S34709, W. Nr./EN 1.4550
Common Applications of 347
- Oil Refineries
- Fluid catalytic cracking units (FCC)
- Firearms production
- Hanger rods
- Recuperator tube sheets, shell, supports
- Especially where temperatures exceed 550°F and resistance to sulfidation is needed
- Fired heater tubes
- Distributor trays and thermowells
- Equipment in and around reactors (good resistance to polythionic acid)
Chemical Composition
347 Chemical Composition
Element
Percent by Weight
C
Carbon
0.080%
Mn
Manganese
200.00%
P
Phosphorous
4.50%
S
Sulfur
0.03
Si
Silicon
75.00%
Cr
Chromium
17.00-19.00
Ni
Nickel
9.00-12.00
Nb
Columbium and
10xC min to 1.00 max
Ta
Tantalum
N
Nitrogen
10.00%
Fe
Iron
Balance
Physical Properties
Physical properties for Type 347 stainless steel
Property | Data | |
Density, lb/in3 | 0.288 | |
Modulus of Elasticity, psi | 28.0 x 106 | |
Coefficient of Thermal Expansion, 68-212˚F, /˚F | 9.3 x 10-6 | |
Thermal Conductivity, Btu/ft hr ˚F | 9.2 | |
Specific Heat, Btu/lb ˚F | 0.12 | |
Electrical Resistivity, Microohm-in |
Mechanical Properties
Mechanical Properties and Yield Strength of 347
Property | Type 321 | Type 347 | |
Yield Strength, 0.2% Offset psi MPa | 30,000 205 | 30,000 205 | |
Ultimate Tensile Strength, psi MPa | 75,000 515 | 75,000 515 | |
Percent Elongation in 2 in. or 51 mm | 40.0 | 40.0 | |
Hardness, Max., Brinell (Plate) RB (Sheet & Strip) | 217 95 | 201 92 |

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