Optimization of Process Variables in Gas Carburizing Process: A Taguchi Study with Experimental Investigation on SAE 8620 and AISI 3310 Steels


Abstract: The utilization of surface engineered materials in various engineering fields has undergone a tremendous increase in recent years, and the need for proper surface engineering of materials has thus increased enormously. However, the knowledge acquired in conventional heat treatment processes, cannot be applied to surface heat treatment processes, of which the hardenability is completely different from that of conventional hardness. Gas carburizing is one of the surface engineering techniques widely used in the process of surface hardening of critical components used in automobile engineering. In this method, the surface composition of the low carbon steel changes by diffusion of carbon and results in a hard outer surface with good wear resistance properties. Fatigue behavior of case hardened parts depends to a great extent on the correct combination of hardness penetration depth and the magnitude of hardness at and beneath the surface with low size and shape distortion. Surface engineering is a complex process in itself, as a number of variables affect the success of the process and quality of the components. One industrial survey indicates that there is a rejection of 10\% - 12\% of case hardened components due to various defects. Quality control is one way to minimize the percentage rejection. Quality control is possible through hardening the components under optimal conditions. This study aimed to optimize the surface hardness and case depth of SAE 8620 and AISI 3310 steel materials. The Taguchi method is a powerful tool in experiment design for the optimization process. An orthogonal array and ANOVA were employed to investigate the influence of major parameters on surface hardness and case depth. Optimum conditions were achieved by applying high hardness and high penetration depth.

Keywords: Quality, Gas carburizing, Process variables, Optimization, Taguchi method

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