Metal magnetic memory testing signals of 45 carbon steel during static tension process

The variations of the magnetic intensity, Hp(y), on the direction perpendicular to the surface of 45 carbon steel tensile specimens with shaft-shaped geometry and three different dimensions were determined during the static tension testing by using the metal magnetic memory. The relationship between the tension stress σ and the absolute value of slope of Hp(y) curve |k| was investigated. In the full elastic range, experimental results showed that, when the dimension of the specimens was given, the magnitude of |k| increased with increasing the loading magnitude. However, near the yield limit in the plastic range, the slope reached a local maximum and then decreased. After abruption, an abrupt change in Hp(y) curve occurred near the fracture surface. When the dimensions of the specimens were different, the relationship between σ and |k| was significantly influenced by the length of the specimens. Results showed that with increasing of the specimen length, the magnitude of |k| decreased.