Chemical Composition
The following table shows the chemical composition of grade 347H stainless steel.
| Element | Content (%) |
|---|---|
| Iron, Fe | 62.83 – 73.64 |
| Chromium, Cr | 17 – 20 |
| Nickel, Ni | 9 – 13 |
| Manganese, Mn | 2 |
| Silicon, Si | 1 |
| Niobium, Nb (Columbium, Cb) | 0.320 – 1 |
| Carbon, C | 0.04 – 0.10 |
| Phosphorous, P | 0.040 |
| Sulfur, S | 0.030 |
Physical Properties
The physical properties of grade 347H stainless steel are given in the following table.
| Properties | Metric | Imperial |
|---|---|---|
| Density | 7.7 – 8.03 g/cm3 | 0.278 – 0.290 lb/in³ |
Mechanical Properties
The mechanical properties of grade 347H stainless steel are displayed in the following table.
| Properties | Metric | Imperial |
|---|---|---|
| Tensile strength, ultimate | 480 MPa | 69600 psi |
| Tensile strength, yield | 205 MPa | 29700 psi |
| Rupture strength (@750°C/1380°F, time 100,000 hours) | 38 – 39 MPa, | 5510 – 5660 psi |
| Elastic modulus | 190 – 210 GPa | 27557 – 30458 ksi |
| Poisson’s ratio | 0.27 – 0.30 | 0.27 – 0.30 |
| Elongation at break | 29% | 29% |
| Hardness, Brinell | 187 | 187 |
Other Designations
Other designations that are equivalent to grade 347H stainless steel include the following:
- ASTM A182
- ASTM A213
- ASTM A240
- ASTM A249
- ASTM A271
- ASTM A312
- ASTM A336
- ASTM A376
- ASTM A403
- ASTM A430
- ASTM A479
- ASTM A813
- ASTM A814
- SAE 30347H
Fabrication and Heat Treatment
Machinability
Machining grade 347H stainless steel is slightly tougher than that of grade 304 steel. However, the hardenability of this steel can be minimized by the use of constant positive feeds and slow speeds.
Welding
Grade 347H stainless steel can be welded using most of the resistance and fusion methods. Oxyacetylene welding is not preferred for this steel.
Hot Working
Forging, upsetting and other hot work processes can be performed at 1149 to 1232°C (2100 to 2250°F). The grade 347H steel has to be water quenched and annealed to obtain maximum hardness.
Cold Working
Grade 347H stainless steel can be readily stamped, blanked, spun and drawn as it is quite tough and ductile.
Annealing
Grade 347H stainless steel can be annealed at temperature ranging from 1010 to 1193°C (1850 to 2000°F) and then quenched with water.
Hardening
Grade 347H stainless steel is unresponsive to heat treatment. The hardness and strength of the steel can be increased through cold working.