Influence cutting parameters on the surface quality and corrosion behavior of Ti–6Al–4V alloy in synthetic body environment (SBF) using Response Surface Method

• The Response Surface Method was used to optimize the turning parameters in machining of Ti–6Al–4V.
• Ra and Rz were influenced by the feed rate with contribution of 98.98% and 96.55%, respectively.
• The biocompatibility was evaluated by the corrosion tests in simulated body fluids.
• The polarization curves showed the formation of a passive layer over all machined surfaces.

Most of the global manufacturing of titanium alloys is related to produce biphasic structures with grains alpha and beta. The development of modern applications of titanium alloy is a great challenge due to the chemical composition of Ti–6Al–4V alloy and the complexity of the manufacturing technology. This study proposed an optimal investigation of the variation of cutting speed, feed rate, and depth of cut in the turning of Ti–6Al–4V alloy on surface roughness, cutting efforts, and corrosion resistance. Response Surface Method has been established to optimize and model the responses mathematically. The adequacy of the models and a significant contribution of parameters were determined by analysis of variance (ANOVA). The biocompatibility of the machined surface for different cutting parameters was evaluated by the electrochemical polarization in simulated body fluids (SBF). Furthermore, desirability function analysis was used to determine the optimal values for surface quality, the turning force, and the passivation rate. It was clearly noticed that the multi-responses of the desirability function improved the machine process. The feed rate and depth of cut were the most relevant factors to minimize surface roughness and the turning forces. Moreover, the experimental results showed that the corrosion behavior was strongly related to minimal surface roughness. Finally, the optimization reduced the surface roughness Ra and Rz in 5.5% and 11.9%, respectively and increased the corrosion resistance in 18.8%.