Classification of Ductile or Brittle Fracture Surface in Steel by Using Anhysteresis Residual Magnetization Method

(In Case of Charpy Impact Test Specimen)

Abstract

Distributions of the leaked magnetic flux vectors are measured at the side of specimens before and after Charpy impact test with or without magnetic field from permanent magnets. Although specimens were demagnetized before the test, neighbors of the notch and the crack line of the specimen were magnetized after the impact test under magnetic field. These phenomena were explained form magnetomechanical effect by Pittman, which makes residual magnetization of ferromagnet metal approach into anhysteresis curve after plastic deformation. Since partial asymmetric residual magnetizations were observed near the crack line, we can estimate intense and area of plastic deformation during the impact test in this anhysteresis residual magnetization method.