Stainless Steel 446 - 1.4749
This data sheet applies to stainless steel 446 / 1.4749 hot and cold rolled sheet and strip, semi-finished products, bars, rods and sections as well as for seamless steel tubes mechanical and general engineering purposes.
Application
For construction parts, which should be resistant to scaling up to about 1100°C and extensively inured to the effects of sulphurous gases. The inclination to carbonisation in reduced gases is very low.
Chemical Compositions*
| Element | % Present (in product form) |
|---|---|
| Carbon (C) | 0.15 - 0.20 |
| Silicon (Si) | 1.00 |
| Manganese (Mn) | 1.00 |
| Phosphorous (P) | 0.040 |
| Sulfur (S) | 0.015 |
| Chromium (Cr) | 26.00 - 29.00 |
| Aluminium (Al) | 0.15 - 0.25 |
| Iron (Fe) | Balance |
Chemical Compositions*
| Element | % Present (in product form) |
|---|---|
| Carbon (C) | 0.15 - 0.20 |
| Silicon (Si) | 1.00 |
| Manganese (Mn) | 1.00 |
| Phosphorous (P) | 0.040 |
| Sulfur (S) | 0.015 |
| Chromium (Cr) | 26.00 - 29.00 |
| Aluminium (Al) | 0.15 - 0.25 |
| Iron (Fe) | Balance |
Mechanical properties (at room temperature in annealed condition)
| Product Form | |||||
|---|---|---|---|---|---|
| C, H, P | L | TS* | |||
| Thickness a or diamter d (mm) | a ≤ 12 | d ≤ 25 | a = 12 | ||
| Hardness HB max. 1) 2) 3) | 212 | ||||
| Proof Strength3) | Rp0.2 N/mm2 | - | |||
| Rp1.0 N/mm2 | 280 | ||||
| Tensile Strength | Rm N/mm2 | 500 - 700 | 500 - 700 | min. 500 | |
| Elongation min. in % | Long Products3) | 15 | |||
| Flat Products | 0.5 ≤ a/d < 3 | 134)5) | - | ||
| 3 ≤ a/d | 154)5) | - | |||
Mechanical properties (at room temperature in annealed condition)
| Product Form | |||||
|---|---|---|---|---|---|
| C, H, P | L | TS* | |||
| Thickness a or diamter d (mm) | a ≤ 12 | d ≤ 25 | a = 12 | ||
| Hardness HB max. 1) 2) 3) | 212 | ||||
| Proof Strength3) | Rp0.2 N/mm2 | - | |||
| Rp1.0 N/mm2 | 280 | ||||
| Tensile Strength | Rm N/mm2 | 500 - 700 | 500 - 700 | min. 500 | |
| Elongation min. in % | Long Products3) | 15 | |||
| Flat Products | 0.5 ≤ a/d < 3 | 134)5) | - | ||
| 3 ≤ a/d | 154)5) | - | |||
Creep Properties (estimated average values about the long-term behaviour at elevated temperature*)
| 1% Elongation1) for | Rupture2) for | ||||
|---|---|---|---|---|---|
| Temperature °C | 1,000 h N/mm2 | 10,000 h N/mm2 | 1,000 h N/mm2 | 10,000 h N/mm2 | 100,000 h N/mm2 |
| 500 | 80 | 50 | 160 | 100 | 55 |
| 600 | 27.5 | 17.5 | 55 | 35 | 20 |
| 700 | 8.5 | 4.7 | 17 | 9.5 | 5 |
| 800 | 3.7 | 2.1 | 7.5 | 4.3 | 2.3 |
| 900 | 1.8 | 1.0 | 3.6 | 1.9 | 1.0 |
Creep Properties (estimated average values about the long-term behaviour at elevated temperature*)
| 1% Elongation1) for | Rupture2) for | ||||
|---|---|---|---|---|---|
| Temperature °C | 1,000 h N/mm2 | 10,000 h N/mm2 | 1,000 h N/mm2 | 10,000 h N/mm2 | 100,000 h N/mm2 |
| 500 | 80 | 50 | 160 | 100 | 55 |
| 600 | 27.5 | 17.5 | 55 | 35 | 20 |
| 700 | 8.5 | 4.7 | 17 | 9.5 | 5 |
| 800 | 3.7 | 2.1 | 7.5 | 4.3 | 2.3 |
| 900 | 1.8 | 1.0 | 3.6 | 1.9 | 1.0 |
Reference data on some physical properties
| Density at 20°C kg/m3 | 7.7 | |
|---|---|---|
| Thermal Conductivity W/m K at | 20°C | 17 |
| 500°C | 23 | |
| Specific Thermal Capacity at 20°C J/kg K | 500 | |
| Electrical Resistivity at 20°C Ω mm2 /m | 0.70 | |
Reference data on some physical properties
| Density at 20°C kg/m3 | 7.7 | |
|---|---|---|
| Thermal Conductivity W/m K at | 20°C | 17 |
| 500°C | 23 | |
| Specific Thermal Capacity at 20°C J/kg K | 500 | |
| Electrical Resistivity at 20°C Ω mm2 /m | 0.70 | |
Coefficient of linear thermal expansion 10-6 K-1 between 20°C and
| 200°C | 10.0 |
|---|---|
| 400°C | 11.0 |
| 600°C | 11.5 |
| 800°C | 12.0 |
| 1000°C | 13.0 |
Coefficient of linear thermal expansion 10-6 K-1 between 20°C and
| 200°C | 10.0 |
|---|---|
| 400°C | 11.0 |
| 600°C | 11.5 |
| 800°C | 12.0 |
| 1000°C | 13.0 |
Processing / Welding
Standard welding processes for this steel grade are:
- TIG-Welding
- MAG-Welding Solid Wire
- Arc Welding (E)
- Submerged Arc Welding (SAW)
Ferritic chrome steels are heat sensitive. Therefore the steel 1.4749 should be welded with lowest possible heat input by using thin electrode diameter, low current intensity and stringer bead welding. For wall thicknesses under 3mm, it is not necessary to preheat 1.4749. For thicker construction parts (> 3mm) the preheating and interpass temperatures 200 - 300°C should not be under respectively over run. 1.4749 can be processed with similar or higher alloyed filler metals. With sulphurous atmospheres a ferritic top layer should be laid on the media side (Thermanit L 1.4820).
Cold Forming
When cold forming 1.4749, certain preventative measures should be observed. Sheets up to 3mm thickness can be cold bent if necessary preheating with 200 - 300°C should be done. Products with thicknesses > 3mm must be preheated up to 600 - 800°C, concerning machinability 1.4749 can be compared to a low carbon steel.
Embrittlement
While heating 1.4749 over about 950°C embrittlement by grain growth occurs, which cant be removed anymore. A further embrittlement occurs in the temperature range between 400 and 550°C (475°C embrittlement). A longer abidance within this temperature range should be avoided. This loss of ductility can be corrected by a short heating up to 700 to 800°C. In the temperature range of 600 to 900°C 1.4749 has the affinity to signma-phase-embrittlement, so that after longer application within this temperature range the ductile values are strongly reduced. The steel should not come into operation within this temperature range, if mechanical stress is existent.
Note
The material is magnetizable.
Heat resisting tubes are delivered regarding testing in accordance to DIN EN 10297-2.
In Germany, SEW 470 still applies for heat resisting tubes.
Editor
thyssenkrupp Materials (UK) Ltd
Cox’s Lane
Cradley Heath
West Midlands
B64 5QU
Important Note
Information given in this data sheet about the condition or usability of materials respectively products are no warranty for their properties, but act as a description. The information, we give on for advice, comply to the experiences of the manufacturer as well as our own. We cannot give warranty for the results of processing and application of the products.