Optimization of Flame Hardening Process Parameters Using L9 Orthogonal Array of Taguchi Approach

S. Jeyaraj, K.P.Arulshri, K. P. Harshavardhan, P.S.Sivasakthivel

Flame hardening is a surface heat treatment process with the application of hot flames obtained from an oxy acetylene gas mixture. About 3000ºC temperature level of gas flame is exposed to work piece material, and bring it out into red hot stage or recrystallization temperature and suddenly quenched by water immediately. Due to these drastic micro structural changes, leads the increase of surface micro hardness. It is mainly influenced by surface temperature, stand-off distance and quenching time. This research article aims with studying the influences of process parameters of flame hardening process by the robust design method. The medium carbon steel specimens were hardened by flame hardening process by adjusting the process parameters. The primary process parameters such as surface temperature of specimen, stand-off distance (SOD) and quenching time were the primary process parameters were investigated experimentally by Taguchi`s approach. L9 orthogonal array was implemented for design of experimental trials based on parameters and its levels. Micro-hardness values of specimens were examined using Vickers micro-hardness tester with the payload of 100g. Optimization model has been developed for micro hardness on the basis of experimental results. The effects of process parameters were analysed by S/N ratio and ranked by order. The optimal parameters were obtained from the S/N ratio analysis has been authorized by confirmatory tests. It was found the greater micro hardness value 801 HV was obtained by the optimal parameters given by taguchi optimization. Such approach is economic one, reduction of experimental trails which will be very suitable for the heat treatment industries.