Application of the Magnetic Method for Control of the Deformed State of Samples Made of ER308LSI Steel Produced by Additive Growing

In modern industry, additive technologies (AT) are being rapidly implemented for the production of materials and products. A significant interest is represented by the Wire Arc Additive Manufacturing (WAAM) technology, which is due to the relatively low cost of equipment and deposited material, as well as a sufficient level of knowledge regarding welding processes. The growth of metallic layers and the manufacture of volumetric parts of various geometric shapes in this case is achieved through wire deposition. Among the deposited materials for three-dimensional printing, chromium-nickel steels have gained wide popularity. Considering the specifics of complex structural and shape-forming processes during the implementation of WAAM, there arises a need for additional research into the structure and properties of the obtained materials. Therefore, the aim of this work is to apply modern nondestructive testing methods for structural degradation during uniaxial tension of ER308LSI steel produced by the electric arc additive manufacturing method. Metallographic and magnetic studies were conducted, and an analysis of changes in microhardness during the deformation of samples cut along and across the printed layers was performed. The features of the structural degradation stages during uniaxial tension and the corresponding behavior of the magnetic parameters of the material were analyzed. It was established that uniaxial tension of samples manufactured using the WAAM method leads to the formation of a large number of structural defects in the form of deformation bands, discontinuities, and microcracks, the appearance of which is accompanied by significant changes in yield strength, microhardness, and coercive force (H_c). On the basis of the obtained H_c values, a magnetic anisotropy parameter (A_magn) was introduced, reflecting the nature of changes in coercive force in samples cut both along and across the direction of deposition. However, the nature of such changes for longitudinally and transversely cut samples (relative to the deposited layers) differs. The results of this work can be applied to the diagnostic tasks of assessing the deformed state of products obtained using the WAAM technology.