Analysis Of The Control And Detection Of Ferrite Content After Stainless Steel Cladding On Cylinder For AP1000 Project

The main equipment of nuclear island is under the neutron radiation and light water corrosion environment, In order to prevent corrosion and radioactive fades on the inner wall material of cylinder, cladding surfaces in contact with the reactor coolant should be applied,At present, DSAW has been used widely, During the design by WEC, in order to prevent the cracking under the overlay, requirement of ferrite content control and measurement method have been established in the specification, due to the effect of the factors such as chemical composition control of material 、welding parameters 、and the measurement election, the ferrite content is difficult to meet the requirements; Although, specification required that the cladding shall be UT for cracking using a 70 degree as a additional in the case of ferrite content is not within specified limits, however, in the actual manufacturing, the schedule and time cost control of manufacturer’s production has been brought considerable influence,Improving the qualified rate of the first layer of ferrite content becomes the key problems of speeding up the progress and cost saving for each manufacturer.Referred to the nonconformance of ferritic content problem of large area stainless steel cladding, This article make a conclusion of how to control the welding layer ferrite content through the analysis of material composition, welding process and measuring method during the nuclear equipment manufacturing and gave the several respects below:1. On the basis of design technique requirement, it has made a strict material purchase specification and optimized the procurement of materials chemical elements through the analysis of raw materials which could affect the ferritic content after cladding.2. Through a variety of process experiments, it found out the orderliness of changing the process parameters with the ferrite content and acquired the effective process parameters of the ferrite content control;3. Through the analysis of the conventional methods of ferrite content detection in their respective characteristics and application scope, it found a suitable process on internal cladding and the combination method for the determination of ferrite content4. Through the application of research conclusion analyzed above to the typical equipment and compared the actual data of two measurements, it demonstrates the technology feasibility and reliability in the ferritic content control for the practical production according to the specifications.Analysis and testing from materials procurement, welding process arrangement, and measurement method to find the affecting of the ferrite content control system have theimportant practical significance influencing on Chinese nuclear manufacturing.