Optimisation of electron-beam surface hardening of cast iron for high wear resistance using the Taguchi method

The paper presents the application of the Taguchi method to develop an optimised electron-beam surface hardening of cast iron for high wear resistance. The experiments were conducted on both the ductile and grey cast iron. The factors investigated during the surface-hardened process included the material matrix, the accelerating voltage, the electrical current, the travel velocity, the melted width, the beam oscillation, and the post-heat treatment temperature. In this study, the L18 and L9 orthogonal arrays were introduced through the two-stage experimental designs and trials. Smaller-is-better was used as a quality characteristic to evaluate the experimental results by computing their signal-to-noise (S/N) ratios of the wear volume after wear tests. It was found that using the Taguchi method coupled with a two-round experimental design strategy is simple, effective and efficient in developing an optimised EB surface hardening process. The experimental results show that the most important process parameters identified are the accelerating voltage, the travel speed, the electrical current and post-heat treatment, respectively. The best wear resistance result obtained through the best combination of process parameters is 8.845×10⁸ kg-mm/ mm³.