Taguchi Approach to Optimize Pack Aluminization Parameters in Carbon Steel Using MINITAB13


Pack aluminization has been rapidly developed and widely used in many fieldsdue to its superior properties of coating. Surface is the only part of the componentwhich has to coexist with external environment. Majority of engineering failuresoriginate from the surfaces and components degrade in service leading to failures suchas fatigue, wear, corrosion and oxidation. The present study deals with the surfacemodification of steel base through diffusion of aluminium by aluminium packcementation for improving wear and corrosion resistance. The material chosen forstudy is medium carbon steel. Effect of varying weight percentage (wt.%) of halideactivator (NH4Cl) at different diffusion temperatures and times on the microstructureand microhardness of aluminized specimens was studied. Taguchi robust designtechnique using MINITAB13 was used to rank several factors that may affect themicrohardness and microstructure in order to formulate the optimum conditions. TheTaguchi orthogonal array L9 (33) was used for experimental design with three level ofconsideration for each factor. The respone (Microhardness) was analyzed based on theTaguchi’s signal-to-noise ratio. The use of 4%wt. of (NH4Cl) at 5hr and diffusiontemperature of 700oC seems to be the optimum condition, where the surface hardnesscould be increased to 1000Hv when aluminized. X-Ray diffraction studies have beenconfirmed the presence of aluminides in the surface layer, which could be instrumentalin the significant increase in the surface hardness.