Additive manufacturing by localized fusion of ER70S-6 wire

Abstract

This study investigates the microstructure and hardness of layers deposited by additive manufacturing via localized fusion (MAFL). Using ER70S-6 wire, a single wall was printed with 41 overlaid layers, employing a MAG-CNC welding machine. The methodology combined thermographic analysis during fabrication, Vickers microhardness tests, and metallographic analysis to correlate temperature, microstructure, and hardness along the part. The main results reveal that the Heat-Affected Zone (HAZ) significantly affects the material hardness, with the lower layers, subjected to multiple thermal cycles, showing the greatest hardness variations (145.20 HV to 181.75 HV). Microstructural analysis demonstrated the heterogeneity of the microstructure, with fine grains at the base due to rapid cooling and coarser grains in the upper layers. By providing new insights into microstructural and hardness heterogeneity, this study deepens the understanding of MAFL-GMAW challenges in manufacturing metal parts. Such information is essential to optimize processes, ensure quality control, and drive the pursuit of innovation.