347 (UNS S34700/1.4550) is a fully austenitic niobium stabilised stainless steel. The addition of Niobium reduces the creation of carbide precipitation in service between 430 to 900 degrees C and during welding processes and increases the mechanical strength of the material.
This grade has good resistance to oxidation and corrosion along with good creep strength and can be used at temperatures where carbide precipitation may occur in non-stabilised grades e.g., 304.
It is used principally in aerospace exhaust manifolds and engine components, chemical processing equipment running at high temperatures and in nuclear processing piping.
Available Tube Product form
Typical Applications
- Nuclear
- Aerospace hydraulics
- Processing & chlorate manufacturing
Industries predominantly using this Grade
- Chemical processing
- Aerospace
Typical Manufacturing Specifications
- British Standards 2T66, 2T68 & T72
- ASTM A269, A213, A312
- SAE AMS 5571
- Also, individual customer specifications.
Technical Data
Mechanical Properties (Room Temperature)
|
Property |
Annealed Temper |
Cold Worked Temper |
| 0.2% Yield (Rp = 0.2) |
30.5 ksi (210 MPa) minimum |
101.5 ksi (700 MPa) minimum |
|
Tensile (Rm) |
80 ksi (550 MPa) minimum |
116 ksi (800 MPa) minimum |
| Elongation (2"gl) |
40% minimum |
10% minimum |
| Hardness |
205 HV maximum |
230 HV minimum |
Physical Properties (Room Temperature)
|
Specific Heat (0-100°C) |
500 |
J/kg/°K |
|
Thermal Conductivity @ 100C |
16 |
W/m/°K |
|
Thermal Expansion |
16.6 |
μm/m/°C |
|
Modulus Elasticity |
195 |
GPa |
|
Electrical Resistivity |
28.7 |
Ohm-cm |
|
Density |
7.93 |
g/cm3 |
Chemical Composition (% by weight)
|
Element |
Min |
Max |
|
C |
- |
0.08 |
|
Mn |
- |
2.00 |
| P |
- |
0.045 |
| S |
- |
0.030 |
| Si |
- |
1.00 |
| Cr |
17.00 |
19.00 |
|
Ni |
9.00 |
13.00 |
| Nb (+Ta) |
10 x C (+N) min |
1.00 |
| Fe |
Balance |