Stress Response of Magnetic Barkhausen Noise in Submarine Hull Steel: A Comparative Study

The development of magnetic Barkhausen noise methods for rapid detection of residual stress concentrations has implications for integrity assessment of submarine pressure hulls. However, the stress-response of Barkhausen noise in submarine hull steel, HY-80, is complicated by the influence of the material's martensitic microstructure. The present work sheds light on the stress-dependent behavior of Barkhausen noise in HY-80 by comparing its signal characteristics with those of more common ferrite/pearlite steels. HY-80 and various ferrite/pearlite steel plates were uni-axially stressed up to and beyond the level for plastic deformation. Barkhausen noise measurements, performed using the same sensor under reproducible flux-controlled magnetization conditions, facilitated a direct comparison of material responses. Results showed that with the application of tensile stress, the Barkhausen noise signal of ferrite/pearlite steels linearly increased, reached a peak value and saturated in the elastic region. By contrast, HY-80 demonstrated a linear increase with tensile stress characterized by a transition from a lower to a seven times higher rate of change for stresses above 200 MPa up to its yield point. The different stress-response of HY-80 was attributed to its martensitic microstructure, which modifies the response of the domain structure under tensile stress conditions.