Sensor-fusion enabled inter-layer temperature control of nano-treated 7075 aluminum alloy produced through wire-arc directed energy deposition process

This study introduces a novel approach to the net-shape fabrication of large-sized 7075 nano-treated (NT) aluminum alloy industrial parts by utilizing the wire arc additive manufacturing (WAAM) process. In this novel approach, an innovative in-house in-situ multi-sensor WAAM system was developed, integrating a profilometer, thermocouple, and an IR camera within the robot operating system (ROS) to achieve a concurrent geometric assessment and temperature recording. A set of experiments was designed and conducted to evaluate the change in geometric and mechanical properties as a function of two different temperature control strategies: fixed interlayer dwell time and fixed interlayer temperature control. Dwell times of 15, 30, and 60 s, along with interpass temperatures of 150, 250, and 350 degrees C, were tested. The results indicated that an interpass temperature of 150 degrees C and a dwell time of 60 s resulted in better performance, specifically in terms of consistency in layer geometry, optimized layer height-to-width ratio, and minimized wall centerline deviation. Mechanical properties, including yield strength and UTS, were evaluated, exhibiting marked anisotropy, where horizontal samples showed better mechanical properties than vertical samples. In both heat management strategies, ultimate tensile strength (UTS) increase as the dwell time increases and the interpass temperature decreases. This trend can be attributed to a more homogeneous cooling rate distribution in samples with higher dwell times and lower interpass temperatures. Additionally, increasing the critical dwell time or decreasing the critical interpass temperature reduces grain size which leads to higher strength in the manufactured part. The high ductility of 7075NT aluminum alloy (around 0.22 fracture strain) suggests the successful adoption of TiC (Titanium carbide) in increasing the ductility of 7075 aluminum parts.