RA330 is a rolled alloy designed for use in thermal processing industries. The alloy was initially known as MISCO, as it was created at the Michigan Steel Casting Company (MISCO), before Rolled Alloys became an independent company in 1953 and the product was renamed RA330. The alloy consists of 35% nickel, 19% chromium and 1.25% silicon.
RA330 is highly ductile and able to withstand high temperatures of up to 1148°C, as well as extreme carburising conditions and repeated quenching. The 35% nickel content is considered the optimal figure for carburisation resistance and it is highly resistant to thermal shock. It also has excellent anti-corrosion and oxidation properties.
RA330 demands strictly controlled production techniques to reproduce the optimal microstructure for thermal recycling. The product is readily welded.
The alloy is formed much like standard stainless steels. In fact, the work hardening rate is similar to that of stainless steel 305. During fabrication, RA330 should not be preheated, the interpass temperature should be kept low and reinforced bead contours should be used.
RA330 has been designed specifically for the heat treatment industry and is commonly used in furnace equipment, as well as:
- Corrugated heat boxes
- Heat treating baskets
- Radiant tubes
- Salt pots
- Heat exchangers
RA330 is welded using filler material that closely matches its own compositional make-up. Manganese is added to create RA330-04 welding wire to resist cracking.