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Ferritic SS 430

Ferritic SS 430

Ferritic SS 430 has a high amount of chromium content (16-18%) in its composition which ensures its commendable resistance to corrosion and oxidation, its maximum scaling temperature is about 820°C. This composition helps the alloy to resist well in nitric acid and sulphur environments, hence it can be widely used in chemical applications.

The alloy also has appreciable resistance to domestically used liquids (soaps), alkaline solutions, dilute organic solutions etc., but it is not very well resistant to the halogen group (Cl, Br, Fr) and a chloride solution can induce stress corrosion cracking. The presence of alpha iron in the grain structure gives the alloy its magnetic properties similar to other Ferritic stainless steel alloys.

The alloy’s carbon content (0.12 % max) is also comparatively higher than previous alloys, which enables the alloy to be easily drawn and formed without much difficulty.

The alloy is often termed non- hardenable as it cannot be hardened by heat treatment due to lesser than required carbon content. Considering its low work hardening rate, it can be easily cold worked and machined. Since the alloy does not harden excessively during cold working, processes like bending, stretching, rolling, deep drawing and upsetting can be suitably done.

The alloy can certainly not be used at cryogenic temperatures, since it might cause a brittle fracture. The chemical composition has no molybdenum with negligible amount of nickel which reduces the cost of metal and fittingly compensating its properties. The alloy has limited application in welded form because even after the alloy being ferritic, the portion at the weld becomes martensitic in nature due to its carbon content. The welded metal needs to be heat treated to about 850°C, for it to be ductile enough for applications. The tensile strength of the alloy at room temperature is around 500 MPa, remains around 450 MPa at 300°C and eventually decreases after 400°C. The alloy might become a little brittle at room temperature after prolong heat treating and cooling, the same can be managed by annealing.

  • Chemical properties
  • Physical properties
  • General data
  • Standards Specifications
  • Forms of Supply
  • Corrosion Resistance
  • Heat Treatment
  • Weldability
  • Machining
  • Applications
  • Possible grade alternatives
Grade   C Mn Si P S Cr Ni C
SS 430 Min - - - - - 16 - -
Max 0.12 1.00 1.0 0.04 0.03 18 0.75 -
Density 7.75 g/cm3
Melting Point 1425-1510°C
Thermal Conductivity @ 70°F 23.9 W/m.K at
100°C
Electrical Resistivity 0.060x10-6 Ω.m
Modulus of Elasticity 200 GPa
Annealing 815-870C°
Standard SS 430
UNS S43000
WERKSTOFF NR. X8Cr17
EN 1.4016
BS 430S17
SWEDISH 2320
JIS SUS 430
OR -
Pipes & Tubes
Summary Standards
Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service ASTM A182
Fittings & Flanges
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 used in general applications, requiring suitable corrosion resistance. It can be used in environments containing mild organic and alkaline solutions, sulphur, nitric acid and food acids. Polishing and buffing on the alloy will improve its corrosion resistance. Resistance to pitting and crevice corrosion is comparatively lesser than chromium-nickel stainless steel alloys. Appreciable resistance to oxidation is provided. At room temperature, till 20% concentration of nitric acid, the corrosion rate of the grade is less than 100 mils/ year (milli-inches per year). In sulphuric acid, it is less than 1000 mils/ year.

The grade cannot be hardened by heat treatment. Annealing is performed to make the grade ductile. It is performed at about 750°C, and then appropriately air cooled, to avoid embrittlement. The annealed metal can be suitably cold worked.

The heat affected zone during welding tends to become embrittled due to formation of martensite phase, and hence post weld ductility is affected of the weld zone. The metal is often pre-heated to about 180- 200°C to avoid the same. Post weld annealing becomes necessary for the metal to be used in dynamic applications, since in the weld condition, the fatigue properties of the metal are poor.

Due to the low work-hardening rate of the metal, it can be easily form, bend and drawn. Conventional machining processes can be suitably used. Intense cold working can be done, with intermediate sub critical annealing (annealing at comparatively lower temperature) The grade can be conveniently hot worked at about 1100°C, for suitable amount of time, since extended time can result in unwanted grain growth and reduction in ductility. Formability and drawing characteristics of the grade are appreciable.

Industrial roofing, wall cladding, equipment in mining and sugar industry, kitchen utensils, automotive trim, molding, gas burners, gutters, refrigerator cabinet panels, dishwashers, furnace combustion chambers, washing machine parts, nitric acid plant equipment, oil refinery equipment, element supports and fasteners,

Grade SS 434
Grade   C Mn Si P S Cr Mo Fe
SS 434 Min. - - - - - - - -
Max. 0.12 1.00 1.00 0.040 0.030 16 1 81
Grade SS 304
Grade   C Mn Si P S Cr Ni
SS 304 Min. - - - - - 18 8.0
Max. 0.08 2.0 1.0 0.045 0.03 20 11.0
Grade SS 316
Grade   C Mn Si P S Cr Ni Fe Mo
SS 316 Min. - - - - - 16 11.00  67.845 2.00
Max. 0.08 2.00 1.00 0.045 0.030 18 14.00 - 3.00

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