Development of correlation between temperature, liquid life span, molten pool, and porosity during Wire Arc Additive Manufacturing: A finite element approach

Abstract

In recent times additive manufacturing (AM) has emerged as a crucial manufacturing process for custom-made metal workpieces. Wire Arc Additive Manufacturing (WAAM) is a rising technology that can cut back material usage and manufacturing time due to its higher deposition rate. This research aims to develop an efficient 3D thermal model to simulate the WAAM process and correlate the temperature with deposition quality. A moving heat source based on Goldac’s double ellipsoidal model was designed using the DFLUX subroutine. The element birth technique has been used to activate the various layers. The developed model is validated with experimentally observed temperature, and a good correlation is obtained. The effect of power and scan speed on the WAAM process has been studied to develop a relationship between maximum temperature, liquid lifetime, and porosity. An X-ray was done to check the porosity of the additively manufactured specimen. At higher power and lower scan speed, the liquid lifetime was observed to be increased along with the increase in depth of the molten pool leading to the formation of porosity. In other cases, at lower power and higher scan speed, the liquid lifetime was observed to be decreased along with the decrease in depth of the molten pool. The higher scan speeds resulted in higher cooling rates, which caused a lack of fusion between the layers of the product. In this case, a ball-shaped melt deposit was observed due to a lower deposition rate due to lower power. • A thermal model is developed to simulate WAAM and is validated with the experimentally observed temperature. • The element birth technique has been used to activate the various layers during the process. • A correlation between maximum temperature, liquid lifetime, and porosity is established. • Temperature contour and liquid lifespan can predict the formation of porosity during the process.