Investigation of the Microstructure and Elemental Composition of Samples Obtained by the Method of Layer-by-Layer Construction by an Electric Arc in a Protected Atmosphere

Abstract

Purpose of research. The article is devoted to the metallographic study of the structure, as well as the elemental composition of the characteristic zones of samples obtained by the method of layer-by-layer construction of an electric arc in a protected atmosphere. The samples for the study were obtained using a mechatronic system with numerical control, which provides positioning of the device for feeding the filler material in the form of a wire along three coordinate axes. The samples were formed on a receiving surface made of steel 3, the material for layer–bylayer construction was alloy steel Sv–09G2S, the electric arc power source was an inverter-type welding machine Cedar MIG–160GDM, the protected atmosphere was a protective gas environment. The layered formation of experimental samples was implemented using the following schemes: in the horizontal plane; in the vertical plane. Preparation for metallographic examination was carried out in accordance with GOST 5639-82 "Steels and alloys. Methods of detection and determination of grain size", GOST R 57180-2016 "Welded joints. Methods for determining mechanical properties, macrostructure, microstructure". The elemental composition of the obtained samples was carried out by X-ray fluorescence analysis using the X-MET 5100 analyzer. As a result of the conducted studies, the presence of voids between single layers in the horizontal plane was revealed; the material of the receiving surface in the root passage zone and the zone of thermal influence have a structure with lower physical and mechanical properties, as well as lower corrosion resistance compared to the material of the receiving surface. The material of the samples formed in the vertical plane has a structure similar in grain size to the material of the receiving surfaceMethods. In the course of the work, methods of microstructure research, as well as elemental analysis were appliedResults. As a result of the work performed on this study, it was revealed that during the formation of single layers on the receiving surface in the horizontal plane, the formation of critical defects - voids and "non-vapors" takes place. The zone of thermal influence, the zone of the root passage contains a metal microstructure that has lower physical and mechanical characteristics and corrosion resistance compared to the material of the receiving surfaceConclusion. When forming products by the method of layer-by-layer construction of an electric arc in a protected atmosphere, the following technological features of the process must be taken into account: in order to prevent the formation of critical defects during layer-by-layer construction of layers in a horizontal plane, it is necessary to establish a range of values of the overlap coefficient of layers; in order to ensure the creation of homogeneous metal structures in the fusion zone of the receiving surface and the construction material, as well as to minimize the size of the zone of thermal influence and the root passage zone, it is necessary to build layers using the receiving surface of materials that maximally correspond in chemical composition to the construction material.