WAAM(Wire Arc Additive Manufacturing) has gained attention as an innovative technology in small-batch, multi-product production due to its advantages of low production costs, rapid build rates, and design flexibility. However, challenges such as relatively low geometric accuracy, surface finish defects, residual stresses, and distortion due to high heat input persist and require improvement. This study analyzes the influence of deposition path angles on deposition performance in the WAAM process. Experiments were conducted using stainless steel (STS309MoL) wire, known for its excellent heat resistance and corrosion resistance due to its relatively high ferrite content within the austenitic structure. To mitigate residual stresses and distortion caused by high heat input, the CMT(Cold Metal Transfer) process was employed for five layers of deposition. Five different deposition path angles were selected as process variables, and the impact of deposition path angles on deposition performance was evaluated based on experimental results.

Due to the necessity of isolating spent nuclear fuel (SNF) from the human life zone for a minimum of 106 years, deep geological disposal (DGD) has emerged as a prominent solution for SNF management in numerous countries. Consequently, the resilience of disposal canisters to corrosion over such an extended storage period becomes paramount. While copper exhibits a relatively low corrosion rate, typically measured in millimeters per million years, in geological environment, special attention must be directed towards verifying the corrosion resistance of copper canister welds. This validation becomes inevitable during the sealing of the disposal canister once SNFs are loaded, primarily because the weld zone presents a discontinuous microstructure, which can accelerate both uniform and localized corrosion processes. In this research, we conducted an in-depth analysis of the microstructural characteristics of copper welds manufactured by TIG-based wire are additive manufacturing, which is ideal for welding relatively large structures such as a disposal canister. To simulate the welds of copper canister, a 12 mm thick oxygen-free plate was prepared and Y and V grooves were applied to perform overlay welding. Both copper welding zones were very uniform, with negligible defects (i.e., void and cracks), and contained relatively large grains with columnar structure regardless of groove types. For improving microstructures at welds with better corrosion resistance, the effect of preheat temperature also investigated up to 600°C.

This study was conducted to compare the mechanical properties of NAB (Ni-Al-Bronze) material manufactured using WAAM (wire arc additive manufacturing) technology and cast NAB that has been used. Two types of mechanical property test pieces were collected from the deposited bulk NAB material according to the direction of deposition, and compared with each other. As a result of mechanical property evaluation, the deposited NAB exhibited anisotropy according to the direction of deposition, and showed high tensile strength, hardness, and shock absorption in the longitudinal direction of the welding line.