Identifying the optimal process parameters to minimize the solid particle erosion rate of heat-treated Ti–6Al–5Zr–0.5Mo–0.2Si alloy using response surface methodology

Abstract This study examines the high-temperature solid particle erosion (HTSPE) characteristics of the heat-treated Ti–6Al–5Zr–0.5Mo–0.2Si titanium alloy, which is widely used in aerospace applications due to its superior thermal stability and excellent mechanical properties. The erosion behaviour was systematically evaluated using a high-temperature solid particle erosion (HTSPE) test rig by varying three key process parameters: specimen temperature (200 °C–750 °C), erodent velocity (30–100 m s −1 ), and impingement angle (30°, 60°, 90°). A Box-Behnken design (BBD) integrated with response surface methodology (RSM) was employed to formulate a predictive model for the response erosion rate. A second-order polynomial regression model was developed, and statistical tests such as analysis of variance (ANOVA), F-ratio, and coefficient of determination were used to analyse the adequacy of the developed model. Impingement angle emerged as the most significant factor influencing the erosion rate, followed by erodent velocity, and lastly, specimen temperature, which exhibited a relatively moderate effect. The process parameters exhibit a parabolic variation with respect to the erosion rate, with no interaction effect observed. The lowest erosion rate, 0.002217 mg g −1 , was achieved at a specimen temperature of 304 °C, an erodent velocity of 35 m s −1 , and an impingement angle of 60°. Field emission scanning electron microscopy (FESEM) was employed to examine the surface morphology, revealing characteristic features associated with different erosion mechanisms. At a 90° impingement angle, material degradation was primarily governed by indentation and ploughing, whereas at a 30° angle, cutting and shear deformation were the dominant mechanisms. These results provide valuable insights for optimising operating conditions to enhance erosion resistance in high-temperature aerospace environments.