Peculiarities of Obtaining and Organising the Structure Oflarge-Size Functional-Gradient Bimetallic Elements Based on Stainless Steel and Copper by Wire-Feed Electron Beam Additive Manufacturing

Studies of the patterns of organization of the structure and properties of large-sized parts based on copper and stainless steel in the printing process by wire additive electron beam technology have been carried out. A 3D printing technique was developed on flat test samples, which ensured the production of defect-free experimental samples with a low degree of mutual mixing of components in the transition zone. Printing was carried out on experimental equipment at the Institute of Strength Physics and Materials Science SB RAS by sequential formation on a stainless steel substrate using an inclined-rotary cooled table of a steel cylinder. Then, with preheating of the steel, copper was applied to it to the entire height of the cylinder. No mechanical treatment of the steel cylinder was carried out between the application of filaments based on steel and copper. According to structural studies, a sufficiently dense contact of copper and steel is formed in the samples, which indicates that all irregularities on the steel cylinder after printing are completely filled with copper. In steel sections of bimetallic elements, the dendritic structure is preserved, in copper sections the structure is granular. The orientation of grains or dendrites in the sample components is related to the local features of the printing process and the direction of heat dissipation. These are related to the geometry of the printing zone during the formation of bimetallic samples, leading to qualitative differences in the structure, varying from fine-grained equiaxed to coarse-grained columnar. The mechanical properties of the copper and steel fragments in the studied samples are at a fairly high level, the strength parameters of the gradient zone have intermediate values.