Using a Parametric Design of Two-Step Processes to Predict Quality Characteristics of Heated Treatment by the High-Density Energetic Beam

This study applies the Taguchi method to elucidate the quality characteristic of the melt depth in electron beam surface treatment (EBST) of cast iron. The-nominal and the-better was a measured quality characteristic to evaluate the experimental results by computing the signal-to-noise ratios (SNRs) of the EBST melt depth after surface-hardening tests. It includes two steps to determine the optimum parameters or conditions. The first step is to maximize SNR to minimize the variance, and the second step is to adjust the EBST melt depth to a target value using the sensitivity. Results from the experiment indicate that the optimal process parameters are a substrate matrix of gray cast iron, a travel speed of 39 mm/s, an accelerating voltage of 10 kV, an electrical current of 15 mA, a melt width of 20 mm, an elliptical beam oscillation, and a post-process heat treatment at 150 °C. The best EBST melt depth obtained in the study was 0.747 mm, corresponding to the maximum SNR. The microstructure is composed of fine dendrites and martensite phases. The obtained EBST depth is confirmed by its falling into the predicted 95% confidence interval. The prediction of the optimal setting is close to the actual target value. The reproducibility of the optimal EBST parameters was experimentally established with data from the confirmation run. EBST wear-resistant surface hardening can be performed using Taguchi experiments.