Analysis of AZ31B – Ti6Al4V bimetallic extrusion by numerical simulation and Taguchi method

Abstract

Abstract This paper investigates the extrusion force and damage induced during an extrusion process to manufacture bimetallic cylinders combining a titanium alloy sleeve (Ti6Al4V) and a magnesium alloy core (AZ31B). A study has been carried out to determine the damage factor distribution through the extrusion process and how this factor together with the extrusion force are influenced by the manufacturing parameters (extrusion ratio, friction and die semi-angle) by means of finite element (FE) simulations. Also, a Taguchi Design of Experiments (DoE) and an Analysis of Variance (ANOVA) have been performed in order to study the influence of each parameter to minimize the extrusion force needed to perform the process and the damage in the extrudate. The results show that damage distribution in the sleeve does not follow any pattern, appearing in different region in a random way. However, in the core the damage always occurs in the region outside the contour of the sleeve, where it reaches the maximum value and afterwards remains stationary during the rest of the process. In the core, damage increases as friction factor does and it is independent of the cross-section reduction for low die semi-angles (15°) and reaches the maximum values for 60° die semi-angle. In both cases, damage and extrusion force, the more relevant factor to obtain minimum values is the die semi-angle.