Ferritic SS 405

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
  • Physical properties
  • General data
  • Standards Specifications
  • Forms of Supply
  • Corrosion Resistance
  • Heat Treatment
  • Weldability
  • Machining
  • Applications
  • Possible grade alternatives
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
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
Standard SS 405
UNS S40500
EN 1.4002
BS -
GOST X6 Cr Al 13
OR -
Pipes & Tubes
Summary Standards
Standard Specification For Seamless Stainless Steel Mechanical Tubing ASTM A511
Standard Specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service ASTM A268

Seamless tubes.

The grade is susceptible to corrosion and rust under various media. The grade has martensitic microstructure, which makes it lesser corrosion resistant than austenitic grades. Post weld heat treatment can increase corrosion resistance.

The alloy can be hardened by soaking it at 982- 1010°C and then performing oil quenching. The alloy prevents itself from extensive hardening from higher temperatures through air cooling. Post processing will require annealing in the alloy for the removal of internal stresses, which can be done by heating the alloy at about 649- 760°C, maintaining the temperature and then cooling.

Shielded fusion and electric resistance welding are the recommended methods for welding the grade SS 405. Oxyacetylene is certainly not suitable and hardening of the grade is controlled with 405 Cb electrodes that contain columbium. Post weld annealing can be required.

Ferritic SS grade 405 is conveniently machined using standard workshop techniques because of its ductile grain structure. Using forming techniques, the alloy can be easily spun, drawn and formed.

Partitions, Steam nozzles, Annealing boxes, quenching racks, lining in pressure vessels.

Grade SS 405
Grade   C Ni Mn Si Cr S Fe P
SS 405 Min. 0.08 - - - 11.5 - - -
Max. 0.15 0.75 1.00 1.00 13.5 0.03 Bal. 0.040

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