Tupolev Kazan National Research Technical University – KAI, Kazan, Russia

S. V. Kuryntsev, Associate Professor of the Department of Materials Science, Welding and Industrial Safety, Candidate of Economic Sciences, e-mail: kuryntsev16@mail.ru

Bauman Moscow State Technical University, Moscow, Russia
I. N. Shiganov, Professor of the Department of Laser Technologies in Mechanical Engineering, Doctor of Technical Sciences

The paper presents the results of studies on the crystallization features of a weld pool made of dissimilar alloys, M1 copper and 12Kh18N10T steel produced by laser welding. In addition to the previously conducted studies on the microstructure, mechanical and operational properties, the authors carried out studies on the microstructure of the top surface of the weld using optical and electron microscopy, and determined the point chemical composition of the differing microstructural components of the weld pool. It was revealed that in the left part of the weld pool, in the center of the grains, there are spherical depressions along the grain bounda ries, point precipitates in the center of the grains and elongated precipitates along the grain boundaries, which significantly differ in the chemical composition. Point and elongated areas contain significantly more copper (18–24%) compared to dark are as that are the body of the grain (8–15%), light areas contain less iron (53–57%) and nickel (7–8%) compared to dark ones containing iron (59–63%) and nickel (7–10%). It has been established that the features of the crystallization of the produced welded joints are an asymmetric crystallization process, a significant difference in the dimensions of the parts of the weld pool from the copper side (1260 μm) and from the steel side (670 μm), the difference in the chemical composition and microhardness of the opposite parts of the weld pool. Microhardness measurements showed that there are minor, but clearly noticeable differences between the left (170–180 HV100) and right (150–155 HV100) parts of the weld pool.

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