Carburization of ethylene pyrolysis tubes determined by magnetic measurements and genetic algorithm

Carburization alters the mechanical and magnetic properties of tubes used in pyrolysis furnaces. In this work, a giant magnetoresistive sensor was used to measure the magnetic flux density at the surface of samples with different carburization degrees. The magnetic measurements were correlated with the volumetric fraction of chromium carbides in each sample. A micro-genetic algorithm was set up to solve the inverse problem, which estimates from the magnetic measurements the spatial distribution of the volumetric fraction of the chromium carbides through the wall.