Magnetic particle indication on magnetic particle testing for valve sleeve (Cr12MoV)

The linear magnetic particle indication was detected on the inner wall surface of valve sleeve (Cr12MoV) in magnetic particle testing process,and the reason of inducing such indication was analyzed by the reinspection of fluorescent penetrant testing and the reinspection of magnetic particle testing and metallographic examination. The results show that the linear indication was caused by carbide zonal segregation of banded structure in the microstructure.