The effects of forced interpass cooling on the material properties of wire arc additively manufactured Ti6Al4V alloy

• Published in: Journal of materials processing technology Vol. 258; pp. 97 - 105
• Main Authors: Wu, Bintao, Pan, Zengxi, Ding, Donghong, Cuiuri, Dominic, Li, Huijun, Fei, Zhenyu
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-08-2018; Elsevier BV
• Subjects: Additive manufacturing; Carbon dioxide; CO2 gas interpass cooling; Cooling; Cooling effects; Deposition; Dislocation density; Dwell time; Evolution; Interpass temperature; Material properties; Mechanical properties; Microstructure; Optical microscopy; Optical properties; Oxidation; Scanning electron microscopy; Thin wall structures; Ti6Al4V; Titanium base alloys; Wire; Wire arc additive manufacturing (WAAM); Wire arc additive manufacturing (WAAM); Interpass temperature; Ti6Al4V; CO2 gas interpass cooling; Material properties
• ISSN: 0924-0136; 1873-4774
• DOI: 10.1016/j.jmatprotec.2018.03.024

To achieve improved microstructure and mechanical properties, an innovative wire arc additive manufacturing (WAAM) process with forced interpass cooling using compressed CO2 was employed in this study to fabricate Ti6Al4V thin-walled structures. The effects of various interpass temperatures and rapid forced cooling on deposition geometry, surface oxidation, microstructural evolution, and mechanical properties of the fabricated part were investigated by laser profilometry, optical microscopy (OM), scanning electron microscopy (SEM), hardness testing and mechanical tensile testing. Results show that the microstructural evolution and mechanical properties of the deposited metal are not greatly affected by an increasing interpass temperature, however, the deposited wall tends to be widened, flattened and exhibit increased surface oxidation through visible coloration. When rapid forced cooling using CO2 is used between deposited layers, slightly higher hardness values and increased strength can be obtained. This is mainly attributed to the combined effects of less surface oxide and high density dislocation caused by the generation of large amounts of fine-grained acicular α within the microstructure. Furthermore, forced interpass cooling not only improves deposition properties, but also promotes geometrical repeatability and also improved manufacturing efficiency through the reduction of dwell time between deposited layers.