Trace Elements in Superalloys and the Implications for Recycling,
NATIONAL PHYSICAL LAB TEDDINGTON (ENGLAND) DIV OF MATERIALS APPLICATIONS
Pagination or Media Count:
The more efficient use of recycled foundry scrap or revert alloy presents an alternative to substitution as a means of conserving strategic raw materials and represents more efficient utilisation of valuable resources. A major difficulty is the inferior foundry performance of revert alloy which can result in hot tearing or unacceptable levels of microporosity so that recycled material has generally been used for the less critical components in the turbine. The present paper considers the general problem of control and specification of impurity elements with particular attention to the situation relevant to recycled alloys and considers ther influence of certain impurities on microstructures and properties. It will be shown that there is scope for the improvement of specifications for impurity elements and that a better understanding of the relationship between casting conditions and microstructure is required for conventionally cast alloys.