SiCromAl grades are a series of ferritic heat resisting stainless steels with varying amounts of silicon, chromium and aluminium. They are useful for temperatures up to 1150°C depending on grade.
This grade combines the following characteristics:
- Good oxidation resistance up to 1150°C for highest grade 1.4762
- Good resistance to sulphidation
- Good resistance to molten metals
- Moderate carburisation resistance
- Greater resistance to thermal shock than austenitic grades
- Can be prone to 475°C embrittlement and sigma phase in some grades
- Loss of toughness above 900°C due to grain coarsening of fully ferritic structure
- Much lower creep strength than austenitic grades
- Poorer weldability than austenitic grades
This series of grades depends on the combined effects of chromium, silicon and aluminium. All of these metals give benefits to the passive oxide layer on the surface of the steel: chromium and aluminium - resistance to oxidation, silicon – resistance to oxidation and carburisation. The absence of nickel leads to better sulphidation resistance than austenitic grades. The lower thermal expansion and higher thermal conductivity compared to austenitic grades makes them more resistant to thermal shock.
Heat exchangers, furnaces, molten metal baths, high temperature nozzles, heat treatment boxes.