Optimization of Hardness in CMT-Manufactured Al-5356 Walls Using Taguchi and ANOVA Techniques

Abstract

The effect of 3D printing parameters on parts hardness has been studied and optimized. Al-5356 alloy parts are manufactured using Cold Metal Transfer (CMT) technique. Torch traveling speed, gas flow rate, and current intensity are the essential CMT factors used. The main objective of the following study is to find and localize the hardness distribution from the bottom to top of CMTed parts and optimize the parameters in order to find out factors that give high hardness. To this end, the following factors have been chosen according to the Taguchi method of an orthogonal L9 design test. The latter method reveals highest optimization corresponds to the top zone, and the low one returns to the bottom zone. Whereas, zones between the top and the bottom have close values of optimized hardness. Besides the Taguchi method, the analysis of variance (ANOVA) was applied to statistically identify the effects of factors and model validation. The results found show that all factors have a significant impact on hardness. SEM images and microstructural studies confirmed the results of the hardness investigation using the Taguchi method. i.e., the top zone part contains more porosity than the bottom. The existence of the latter affects the hardness. In addition, microstructural investigation shows that the small grain size is located at the bottom, in contrast to the top due to the rapid solidification of aluminium and different heat distribution.