Polysilicon plant in China selects RA330 for longer life.

In the U.S., RA330 is the workhorse of the heat resistant alloys. It has good strength, carburization and oxidation resistance to 1150℃. If the application is in high working temperature with corrosion, RA330 is one of the best choices. In China, this has been a difficult sell because of the extremely low cost stainless options. 

One recent success happened in a polysilicon plant where lower alloys were failing.  Polysilicon is the raw material of electronics and photovoltaic industries.  There is a high temperature reducing furnace in part of the polysilicon making process. It is used for making Polysilicon, which takes pure trichlorosilane in a hydrogen atmosphere to a reducing deposit. This equipment working temperature is generally from 1050℃to 1200℃, with hydrogen and hydrogen chloride atmosphere. The following is the reaction formula:

SiHCl3+H2→Si+HCl

The composition of RA330 determine its good resistance to H2 and high temperature. In contrast 316L and 310S cannot endure both high temperature and more corrosion. Higher options like 601 or 602CA were not accepted because of high price. RA330 is the most economical alloy in high temperature applications, especially from 1050℃ to 1150℃. 

 

There is a slow change in the Chinese market where life cycle cost is becoming more important than initial cost.  Even though labor and repair costs are low, downtime is critical.  For this reason, lower grade stainless steels, like 310 are being replaced with more suitable alloys, like RA330.

David Wei

Rolled Alloys, China