Method for the reduction of noise during the Eddy-current testing of tubes and tubes produced with that procedure.

摘要

The method relates to the capacity for detecting defects using eddy currents on metal tubes cold-rolled by means of a pilgering (pilgrim) roll, and more particularly relates to the possibility of decreasing the background noise and increasing the ratio between a standard signal and this background noise. The method consists in carrying out, after a cross-sectional reduction of at least 30 % at the pilgering cold roll, a pass with hollow drawing with reduction in the external diameter by approximately 0.1 to 5 %. The signal/background noise ratio can thus be multiplied by a factor of between 2 and 3.7 in the case of a batch of tubes made of INCO 690 alloy, as shown by the single figure. The invention also relates to tubes produced using the method. Application to producing steam generator tubes for nuclear power stations. <IMAGE>