Research Article Investigation in Gas Carburizing of AISI 4140, EN36, and 16MnCr5 Steels Using the Grey Incidence-Based Taguchi (GIBT) Method G. L. Arumparithy , 1 R. Adalarasan , 1 M. Santhanakumar , 2 N. Balaji , 3 and Yalew Asres 4 1 Department of Mechanical Engineering, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, andalam, Chennai, Tamil Nadu 602105, India 2 Department of Mechanical Engineering, GRT Institute of Engineering and Technology, GRT Mahalakshmi Nagar, Tiruttani, Tiruvallur Dist, Tamil Nadu 631209, India 3 Department of Mechanical Engineering, Saveetha Engineering College, andalam, Chennai, Tamil Nadu 602105, India 4 Department of Mechanical Engineering, Faculty of Manufacturing, Institute of Technology, Hawassa University, Hawassa, Ethiopia Correspondence should be addressed to Yalew Asres; yalewa@hu.edu.et Received 5 May 2022; Accepted 8 July 2022; Published 9 August 2022 Academic Editor: V. Vijayan Copyright © 2022 G. L. Arumparithy et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Gas carburizing is an effective surface treatment process for improving the hardness and wear resistance of different class of steels. e study reports an application of grey-incidence based Taguchi (GIBT) method in gas carburizing of case-hardening steels like AISI 4140, EN36, and 16MnCr5 which are widely employed in precision levers, transmission shafts, and pinions. Carburizing trials are performed using Taguchi’s L 9 orthogonal array by varying the design parameters like carburizing temperature, soaking time, and tempering temperature. Surface hardness (SH), diffusion depth (DD), and wear loss (WL) are studied as process responses at the completion of various carburizing trials with replications. Optimal design variables are identified using grey incidence grade as a performance index in the GIBT method. e contribution of individual parameters is also studied using the analysis of variance (ANOVA). Microscopic examination and SEM images of the treated surface are also studied after validating the method of GIBT. 1. Introduction Surface hardening is an important process to improve wear resistance and hardness in machine parts like shafts, cam rollers, strips, pinions, etc. Gears used in automobiles and power mills encounter high specific loads due to greater torque requirements. Improving the life of such components including an offer of lifetime warranty was possible by surface treatments like carburizing. Gas carburizing is a case-hardening process in which carbon is diffused into the workpiece surface by heat treatment in an atmosphere of carbon carrying gas. Normally, methane or propane gas is used to create an atmosphere with carbon potential along with a neutral gas. e part is finally quenched and tempered to complete the sequence. Pack carburizing consumes time and hence is limited in applications. Gas carburization is found to be the more effective one than both vacuum and plasma carburizing. e process does not harden the steel directly; however, it improves the carbon content to a sufficient level beneath the surface for subsequent quenching and tempering [1]. Soaking time and carburizing temper- ature play a vigorous part in diffusion of carbon atoms and diffusion depth depend on these parameters. A controlled gas carburization could produce a well-defined carbon profile with an endothermic gas like carbon monoxide [2]. In most cases, the temperature was not increased beyond 980 o C though faster carbon diffusion was possible at higher temperatures, saving the process time as well. Necessary care was essential to select an appropriate furnace and reduce the grain coarsening in parent steel. e gas carburizing Hindawi Advances in Materials Science and Engineering Volume 2022, Article ID 6102139, 10 pages https://doi.org/10.1155/2022/6102139