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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2015, Vol. 36 ›› Issue (10): 3450-3456.doi: 10.7527/S1000-6893.2015.0173

• Material Engineering and Mechanical Manufacturing • Previous Articles     Next Articles

Micro-magnetic NDT for surface crack defect in a GH4169 turbine disc simulated by artificial groove

HU Bo1, YU Runqiao1, XU Weijin2   

  1. 1. Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang 330063, China;
    2. Safety Environment Quality Surveillance and Inspection Research Institute, CNPC Chuanqing Drilling Engineering Co., Ltd., Guanghan 618300, China
  • Received:2015-04-09 Revised:2015-06-06 Online:2015-10-15 Published:2015-06-09
  • Supported by:

    National Natural Science Foundation of China (51265041, 51565043), Youth Science Foundation of Jiangxi Province (20151BAB216016), Youth Science Foundation of Education Department of Jiangxi Province (GJJ13488).

Abstract:

This study proposes a micro-magnetic nondestructive testing (NDT) method in the geomagnetic field to detect the surface crack defect in a turbine disc. The magnetization characteristic curve of extensively used nickel base superalloy GH4169 is obtained by magnetized test. It is proved that the relative permeability of the material is slightly greater than the relative magnetic permeability of the air through the magnetic analysis. Thus, GH4169 is a weak paramagnetic substance. The mechanism of the micro-magnetic NDT method suitable for turbine disk specimen and magnetic anomaly characteristics of the defect are analyzed. The correctness of the theoretical analysis is verified through the testing of a turbine disk contained artificial crack defects. Test results show that the width and peak of the magnetic anomalies increase along with the increase of width and depth of surface crack. When the widths of cracks are the same, the deeper the depth, or the larger the deep width ratio, the greater the magnetic anomaly, and the position of crack has a certain influence on the positioning accuracy. The micro-magnetic NDT method provides new thoughts for the detection of surface crack defects of a turbine disc. The method can be further popularized and applied to other parts of the aeroengines, such as rotor blades, turbine shaft and the aircraft fuselage with similar magnetism features.

Key words: turbine disc, crack, micro-magnetic, nondestructive testing, geomagnetic field

CLC Number: