Volgograd State Technical University, Volgograd, Russia
L. M. Gurevich, Dr. Eng., Associate Prof., Head of the Dept. of Materials Science and Composite Materials, e-mail: mv@vstu.ru
V. N. Arisova, Cand. Eng., Associate Prof., Dept. of Materials Science and Composite Materials
V. O. Kharlamov, Cand. Eng., Associate Prof., Dept. of Equipment and Welding Technology

Abstract: The results of studies of the transformation of the structure of the near-weld zone of a two-layer explosion-welded composite material carbon steel 20 + alloyed martensitic corrosionresistant steel 50Cr15Mo2V after normalization at temperatures of 800–1100 °C and holding times from 1 to 20 hours are presented. It has been established that at 800 °C there is a "reverse" diffusion of carbon – from steel 20 with a lower concentration into steel 50Cr15Mo2V with the formation of a decarburized layer in steel 20. With a further increase in temperature, carbon atoms diffuse into steel 20 together with chromium atoms, changing the structure of the near-weld zone (an increase in the volume content of perlite and the formation of martensite in steel 50Cr15Mo2V). It is shown that the normalization of the bimetal steel 50Cr15Mo2V + steel 20 with an increase in exposure time to 5-20 hours at a temperature of 1000 ° C leads to the formation of a continuous diffusion decarburized zone. It has been established that the formed diffusion decarburized zone is characterized by a variable chromium content from 2 to 9 at.%. At exposure times up to 10 hours, the thickness of the diffusion decarburized zone increases, and with a further increase in the exposure time to 15-20 hours, it decreases. The complex nature of the change in the thickness of the light decarburized zone is explained by the different intensity of the three parallel diffusion processes of the carbide-forming elements.

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