Taguchi Optimization of Electrolytic Plasma Hardening Process Parameters on Ti-6Al-4V Alloy: Microstructure and Mechanical Properties

Abstract

Herein, the effects of electrolytic plasma treatment (EPT) on the hardness distribution, wear resistance, and surface morphologies of titanium alloy (Ti-6Al-4V) at three different thermal cycles (4-5-6 times) are investigated. The microstructure is controlled by heat temperature and modification times of thermal cycles depending on EPT processing parameters. A novel technique to modify Ti-6Al-4V alloy by the process of EPT successfully occurs. The results show that the phase transformation is shown as follows: fine α and β for the low thermal cycle → irregular martensite α′ for the high thermal cycle → complete zigzag martensite α′ for the max thermal cycle. The hardness is increased from 350 ± 10HV0.05 to 530 ± 10HV0.05 after the modification. Wear tests are conducted according to the Taguchi L9 (3^3) orthogonal array. Three parameters (load, sliding speed, and sample type) with three levels examine wear rate and coefficient of friction. Optimum levels are obtained by Taguchi analysis from the experimental results. In addition, an analysis of variance is performed to find the effectiveness of the parameters. The wear surfaces are analyzed by scanning electron microscope. After the analysis, the best result is obtained in five thermal cycles.