Mechanical Barkhausen noise during fatigue of iron

In this paper, the potentiality for using the mechanical Barkhausen noise (BN) to monitor fatigue tests of ferrous materials is investigated. The fatigue tests are carried out on iron specimens subjected to rotational bending on a standard fatigue bench. The mechanical BN is detected using an encircling coil. The mechanical BN exhibits three main stages during the fatigue life: it increases at the beginning of the test, then a plateau is reached and finally it decreases before rupture. These successive stages can be associated to the classical stages of the fatigue life of metals and alloys: crystalline microstructure changes, a saturation stage, and microcrack nucleation and growth leading to rupture. An early indicator of damage is derived from the results.