Detection Method of Ferrite Content and Composition Segregation Control of the Centrifugal Casting Main Pipe of the Nuclear Power Station

According to the requirement of RCC-M, the material of the main pipe of CPR1000 PWR nuclear power station is centrifugal casting austenitic-ferritic stainless steel (French grade Z3CN20-09M). According to Schaeffler diagram of chapter MC1000 and the content of chapter MC1340, the ferrite content of the main pipe was measured, and the causes of results difference between different methods were analyzed. Combined the manufacture experience of the main pipe of Yangjiang project and the content of chapter RCC-M M3406, the reasons why the ferrite content of the main pipe increased from inner wall to outer wall were also analyzed from metallurgy theory and the solidification characteristics of centrifugal casting. The application scope of the ferrite content measurement methods of Schaeffler diagram and chapter MC1340, and the method to eliminate the uneven distribution of ferrite in the main pipe were concluded.