Microstructural and microhardness characterization for the UTP AF Ledurit 60 flux-cored wire deposited by the wire arc additive manufacturing (WAAM) technique

Abstract

The Additive Manufacturing (AM) technique has been gaining ground since its introduction in Germany in 2011 as one of the pillars of Industry 4.0. Since then, various materials, such as metals, have been studied. This work focuses on the layer-by-layer deposition of a high-mechanical-strength wire designated as UTP AF LEDURIT 60. This material possesses high hardness and is used for welding applications involving combined wear from friction and metal-to-metal compression. Therefore, the objective of this study is to understand the microstructural and microhardness behavior of this material when applied via AM. For this, a part was printed with dimensions of 40 millimeters (mm) in length, 35mm in width, and 30mm in thickness. Subsequently, optical emission spectrometry tests were conducted to determine the chemical composition, metallographic analysis for microstructural characterization, and Vickers microhardness testing to understand the material's resistance to surface deformation. For the spectroscopy analysis, the result was close to that specified by the manufacturer; however, there were some discrepancies in the result due to the arc welding deposition, related to the interactions between the deposited material and the base material. The microhardness for this wire reached an average of 780±91 HV, with some regions reaching up to 964.42 HV. The microstructure was characteristic of a high-chromium white cast iron, as expected for the UTP AF LEDURIT 60 wire. The white blocks in the microstructure are characteristic of primary chromium carbides dispersed in a cementite matrix, which explains the high hardness.