Use of Taguchi Methods for Hierarchy of Influence Factors in the Application of Carbonitration in a Fluidized Bed Steel for 41Cr4 Steel

Résumé

The work is based on carbonitriding in a fluidized layer with methane and ammonia gas applied to 41Cr4 steel samples. To achieve the best possible results, other factors must be taken into account, than those specific to carbonitring. It was necessary to use a partially factorial working procedure due to the increase in the number of factors. An A18 matrix has been used, with 18 lines of experiments in which three levels have been modified for 6 factors. The objective function was fixed at the final hardness after carbonitriding, hardening and tempering. The carbonitriding was performed in fluidized bed with granular solid ground and sorted to 0.1- to 0.16mm, and brought to fluidization with a mixture of methane and ammonia. The hardening has been done directly after carbonitriding in the fluidized bed. The experiments have been performed according to Taguchi Methods and the results indicate an optimal regime and the influence of the factors considered on the hardness after the thermo-chemical treatment and the thermal treatment. Metallographic analysis has been performed on the carbonitrided layer.