Influence of specimen carbon content on a magnetic anisotropy sensor sensitivity in stress measurement

A magnetic anisotropy sensor (MAS) is described which enables the user to measure internal stress in steel with no contact. The operating principle of the MAS is explained and an expression representing the stress-dependent output voltage is derived. The MAS can easily reduce hysteresis for stress measurement by demagnetizing. The authors have proved the alternating demagnetizing method to be useful. It is also clarified that the measurement sensitivity varies with the carbon content of the specimen. The higher the MAS output voltage sensitivity, the lower the carbon content when the surface stress was 40 MPa for a carbon content of 0 to 0.5%. This indicates the possibility that the carbon content can be measured by checking the sensitivity of a specimen to stress