On-line measurement system for the degree of alloying

Fully automatic on-line optical measurement system for the degree of alloying in galvannealed steel sheet has been developed. In this system, the degree of alloying is measured by detecting the reflectance of galvannealed steel sheet using laser. Since the surface roughness of coated layer scatters the reflected laser beam and reduces the intensity of reflected light, which can be calibrated by measuring the intensity of scattered light in addition to the specularly reflected light. After calibration, the degree of alloying shows the linear relationship with the measured reflectance regardless of surface roughness. According to in-line process experiment, this type of optical measurement technique is reliable to the on-line measurement of the degree of alloying in the process of galvannealing steel strip. Copyright (C) 1998 IFAC.