A Part of History
Rolled Alloys and our RA330 alloy were both created to service the need of the thermal process industries for a reliable source of a wrought alloy that could handle the rigors high temperature carburizing conditions and repeated quenching. Both our company and our RA330 alloy product began as parts of the Michigan Steel Castings Company (MISCO). The predecessor to RA330 was an alloy known as MISCO metal, it was a rolled version of the cast HT alloy and 35% nickel, 15% chromium. Its success came as a replacement to castings which were less ductile and fractured during harsh temperature cycling.
In 1953, Rolled Alloys became an independent company and MISCO metal became RA330 alloy. Over the past 60 years, we have applied our knowledge and close working relationship with the thermal process industry to modify RA330 to optimize its performance. These efforts include adjusting its chemistry to its current 35% nickel, 19% chromium, 1.25% silicon and controlled production techniques to ensure a product that has the optimal microstructure to withstand repeated thermal cycling.
RA330 is a patented alloy designed specifically for the heat treat industry. To this day, RA330 outperforms the generic version made only to UNS N08330. In addition to meeting the requirements of UNS N08330, Rolled Alloys has tighter chemistry restrictions and proprietary heat treatments to produce an optimum product. Even the weld wire, RA330-04, has increased levels of manganese to avoid hot cracking. When buying a heat resistant alloy, insist on quality, insist it is RA330.
RA330 alloy is an austenitic heat and corrosion resisting alloy offering an exceptional combination of strength and resistance to carburization, oxidation and thermal shock. Carburization and oxidation resistance to 2100°F (1148°C) are enhanced by a nominal 1.25% silicon addition. RA330 alloy finds wide application in high temperature industrial environments where good resistance to the combined effects of carburization and thermal cycling are required. RA330 alloy remains fully austenitic at all temperatures and is not subject to embrittlement from sigma formation.
ASME SB 511, ASME SB 710
ASTM B 511, ASTM B 512, ASTM B 535, ASTM B 536, ASTM B 546, ASTM B 710, ASTM B 739
RA330® Expanded Metal, RA330® Hex Nuts, RA330® Pipe, RA330® Plate, RA330® Rod Coil, RA330® Round Bar, RA330® Sheet, RA330® Threaded Bar, RA330® Washers, RA330® Welding Products
Common Trade Names
UNS N08330, Alloy 330
- Oxidation resistance to 2100°F (1148°C)
- Resistant to carburization and nitriding
- Resistance to thermal shock
- Good strength at elevated temperature
- Metallurgical stability
- Corrugated Boxes
- Bar Baskets
- Radiant Tubes
Carburization resistance is a prime consideration when selecting an alloy for industrial heating applications. The 35% nickel content of RA330 has long been considered optimal for both mechanical properties and carburization resistance. Silicon, maintained at a nominal 1.25%, is recognized as the one element most potent in providing resistance to carburization. Carburization rates are also affected by mechanical and thermal strains which damage the protective scale. The relative carburization resistance of commercial alloys is most reliably studied by exposing the materials to actual service conditions.
RA330 is readily welded using RA330-04 weld fillers of matching composition. RA330-04-15 DC lime type electrodes are available from stock in popular sizes. RA330-04 bare welding wire is available as straight lengths for GTA welding or spooled for GMA welding.
For best results do not preheat, keep interpass temperature low and use reinforced bead contours.
RA330 is formed in the same manner as the conventional austenitic stainless steels. The work hardening rate of RA330 is comparable to that of 305 stainless.
RA330 and other austenitic grades are quite ductile in the annealed condition. However, when machining, these chromium-nickel alloys work harden more rapidly and require more power to cut than plain carbon steels. Chips tend to be stringy, cold worked material of relatively high ductility.
For further information on fabricating RA330, please refer to the RA330 Fabrication Manual.
RA330 is highly resistant to oxidation under cyclic conditions, providing useful service life at extreme temperatures. The following laboratory data illustrates the relative performance of RA330 and other materials at elevated temperature.