FERRITIC SS 405
The 400 series in the ferritic stainless-steel group have about 11-12% Cr and 1% Mn. The grain structure of ferritic stainless steel is BCC (body centred cubic) in comparison to austenitic stainless steel which has its grain structure as FCC (face centred cubic), the alpha iron in ferritic stainless steel is what gives it its magnetic properties.
The 11-12% Cr in the ferritic SS 405 makes the metal corrosion resistant. Though it has lesser resistance than other alloys in the series but it possesses excellent dimensional stability, suitable welding properties, appropriate pitting resistance and comes at a low cost. The alloy is principally used in the lining of pressure vessels. It has carbon content of maximum 0.08%, which prevents it from getting brittle at allowable temperatures.
It has a shear modulus of 76 GPa, making it suitable for applications which are dynamic and require shear strength. The alloy is typically furnished in annealed condition. Electric resistance as well shielded fusion welding methods are normally used in its production.
The ductility of the alloy is maximized by post welding annealing, which results in removal of internal stresses. The alloy can be conveniently machined due to its soft and ductile characteristics. The thermal conductivity of the alloy is 27 W/mK, which is appropriate to be used in engineering applications. Unlike other grades with 12% Cr stainless, the SS 405 is invulnerable to extensive hardening through air cooling from higher temperatures.
Forging can be done on this grade appropriately, by first soaking the alloy at the temperature of 850 °C, and then increasing to about 1150 °C. The process is followed by air cooling and annealing.
CHEMICAL PROPERTIES
| Grade | C | Al | Mn | Si | Cr | S | Fe | P | |
| SS 405 | Min. | – | – | – | – | – | – | – | – |
| Max. | 0.08 | 0.2 | 1.00 | 1.00 | 13.00 | 0.030 | 85.00 | 0.040 |
PHYSICAL PROPERTIES
| Density | 7.80 g/cm3/0.282 lb/in³ |
| Melting Point | 1325 -1370 (°C) / 2415 – 2500 (°F) |
| Thermal Conductivity @ 70°F | 27.0 W/mK/187 BTU in/hr.ft².°F |
| Young’s Modulus E GPA | 220 |
| Shear Modulus E GPA | 83.5 |
| Resistivity(μΩ.cm) | 60 |
| Permeability At 200 Oersted (15.9 Ka/M) | 1.0002 |
| Annealing | 750/800°C (1382 /1472°F) |
| Poisson’s Ratio | 0.27-0.30 |
APPLICATIONS
Partitions, Steam nozzles, Annealing boxes, quenching racks, lining in pressure vessels.
FORMS OF SUPPLY
Seamless tubes.