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
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 | – |
PHYSICAL PROPERTIES
Density | 7.75 g/cm3 |
Melting Point | 1425-1510°C |
Thermal Conductivity @ 70°F | 23.9 W/m.K at 100°C |
Electrical Resistivity | 0.060×10-6 Ω.m |
Modulus of Elasticity | 200 GPa |
Annealing | 815-870C° |
APPLICATIONS
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,
FORMS OF SUPPLY
Seamless tubes.