These type of stainless is austenitic chromium steel containing columbium. They are recommended for parts fabricated by welding which cannot be subsequently annealed. These types also are used for parts which are intermittently heated and cooled to temperatures between 800 and 1600ºF. The addition of columbium produces a stabilized type of stainless that eliminates carbide precipitation, and consequently, intergranular corrosion.
Superior general corrosion resistance over type 321 due to stabilization with Columbium. Better high temperature properties than 304 or
304L. Generally used for parts which are intermittently heated up to 1500ºF (815ºC) . For continuous service the maximum temperature is
1650ºF (900ºC). Type 347H has high carbon (0.04 to 0.10) for better high temperature creep properties. Improved intergranular corrosion
resistance.
Specifications
| AISI 347H – UNS S34709 | |
| Product | Norm ASTM |
| Seamless Tubes | A-213 A-312 |
| Welded Tubes | A-249 A-312 |
| Plates | A-240 |
| Bars | A-276 A-479 |
| Flanges | A-182 |
| Fittings | A-403 |
Chemical specifications %
| AISI 347H – UNS S34709 | ||
| Element | Simbol | Maximum |
| Carbon | C | 0,04-0,10 |
| Manganese | Mn | 2,0 |
| Phosphorus | P | 0,045 |
| Sulfur | S | 0,030 |
| Silicon | Si | 1,0 |
| Nickel | Ni | 9,0-12,0 |
| Chrome | Cr | 17,0-19,0 |
| Niobium | Nb | 8 x C |
| Iron | Fe | Balance |
Mechanical Properties
| AISI 347H – UNS S34709 | |||||||
| Norm | Rm min. | Rp 0,2% min. | E4d min.% | Z min.% | T.I.(J) | HR B | HB |
| A-182 | 75 (515) | 30 (205) | 30 | 50 | |||
| A-213 | 75 (515) | 30 (205) | 35 | 90 | 192 200 HV | ||
| A-240 | 75 (515) | 30 (205) | 40 | 95 | 201 | ||
| A-249 | 75 (515) | 30 (205) | 35 | 90 | |||
| A-276 | 75 (515) | 30 (205) | 30 | 40 | |||
| A-312 | 75 (515) | 30 (205) | |||||
| A-403 | 75 (515) | 30 (205) | |||||
| A-479 | 85 (585) | 65 (450) | 30 | 60 | |||
