Dilution sensing during laser cladding and alloying

Abstract

To achieve a good fusion bond of clad /alloying to substrate with controlled level of dilution requires careful arrangement and precise control of operating parameters. Until now dilution has been measured destructively using optical microscopy or scanning electron microscopy. This paper describes a non-destructive dilution sensor which can be used for both off-line dilution examination and on-line process monitoring and quality control. The sensing has been realised by generating an alternating magnetic flux into the clad/alloy layer which forms part of the magnetic circuit. Changes in material permeability and conductivity are detected. By comparing this signal to pre-calibrated signals corresponding to 0% and 100% dilution, i.e. the sensor responses to clad material and the substrate materials, the level of dilution can be evaluated in real time. The effect of air gap variations is compensated by employing dual frequencysensor excitation, thus enabling non-contact dilution sensing. Both theoretical analysis and experimental data are presented.To achieve a good fusion bond of clad /alloying to substrate with controlled level of dilution requires careful arrangement and precise control of operating parameters. Until now dilution has been measured destructively using optical microscopy or scanning electron microscopy. This paper describes a non-destructive dilution sensor which can be used for both off-line dilution examination and on-line process monitoring and quality control. The sensing has been realised by generating an alternating magnetic flux into the clad/alloy layer which forms part of the magnetic circuit. Changes in material permeability and conductivity are detected. By comparing this signal to pre-calibrated signals corresponding to 0% and 100% dilution, i.e. the sensor responses to clad material and the substrate materials, the level of dilution can be evaluated in real time. The effect of air gap variations is compensated by employing dual frequencysensor excitation, thus enabling non-contact dilution sensing. Both theoretical ana...