FERRITIC SS 444
Ferritic SS 444 is a superior grade alloy with highly stabilised chemical composition, mechanical and thermal properties. With a 2% Molybdenum in its composition reinforced with titanium and niobium, a fully stabilised microstructure with excellent surface properties is obtained.
The 18% Chromium content in the alloy ensures a microstructure with brilliant corrosion resistance, crevice corrosion, pitting resistance, oxidation and creep resistance even at elevated temperatures. The alloy has low nitrogen and carbon content that takes care about the ductility of the metal.
The alpha iron in the grain structure gives the alloy its magnetic properties, being ferritic in nature, the alloy is also resistant to stress corrosion cracking. The alloy remains ferromagnetic at all conditions.
Unlike previous ferritic stainless steel alloys, the grade 444 has superior resistance in chloride environments, and can resist chloride stress corrosion cracking. The grade has lower thermal coefficient of expansion, with a value of 10 micrometre/m°C and hence, it can be used suitably in applications at elevated temperatures.
The poisson’s ratio of 0.27-0.30 depicts the stiffness of the SS grade. The tensile strength of the material decreases from 500MPa at 100°C to 400MPa at 500°C. The grade can be suitably forged and hot worked by heating the metal up to 1000°C, and then finishing temperature below 700°C. The metal should not be held above 1000°C for extended period of time since that would result in grain growth and unwanted loss of ductility. The hot working needs to be followed by annealing, for stress removal and passivation of the surface for corrosion resistance.
The grade can be suitably cold worked with low work hardening rate and has deep drawing, bending characteristics with good formability. The alloy has 65 GPa torsional modulus of elasticity at room temperature, and hence can be suitably used in dynamic applications.
|Ti + Nb
|7.80 g/cm3/0.282 lb/in³
|1 405-1 495°C
|Thermal Conductivity @ 70°F
|26.8 W/mK 186 BTU in/hr.ft².°F
|0.102 BTU/lb-°F @ 70°F
427 J/kg-°C @ 20°C
|Modulus of Elasticity
|200 GPa 29000 ksi
|760-830 C °
Food processing and wine making equipment, roofing and cladding in marine environments, hot water tanks and geysers, automotive components and heat exchanger tubings.
FORMS OF SUPPLY