Abstract
Materials and components undergo the highest loads at their surfaces. To withstand mechanical loads, many methods are in use to increase surface and near-surface hardness. Conventional hardness and depth-of-hardness testing is destructive, time-consuming, and expensive. Therefore, there is an increasing demand for nondestructive testing techniques. Eddy current as well as modulated field-eddy current methods are suffering from undefined boundary conditions. This paper shows the correlation between magnetic. Barkhausen noise and hardening depth for components like crank shafts, racks, and brake pulleys. The method promises to work up to hardening depth values of about 5 mm.