CREATION OF SPECIAL CONSTRUCTION MATERIAL USING THE ROLLING METHOD OF ASYMMETRICAL PACKAGES FOR DUAL-PURPOSE PRODUCTS

Abstract

Purpose. The object of research in this work was the creation of a bimetallic material with increased mechanical and operational properties by rolling asymmetric packages. According to the preliminary results of the structure and properties research, the optimal compositions of the base and cladding layer of the bimetallic workpiece with the smallest difference in thermal expansion coefficients were selected. With the help of asymmetric rolling of base packages – steel 14Х17Н13КМБх + cladding layer-steel 03Х17Н3Г9МБДЮч, a bimetallic workpiece was made, which had low stresses in the welded seam and the zone of thermal influence, unlike the package 14Х17Н13КМБх + 10ХФТБх. Therefore, no grooving and thermal cracks were observed in the bimetal samples during the magneithermal production of spongy titanium. The inflow of nickel into spongy titanium from the surface of the plating layer during the recovery process did not exceed 0.004 % by mass. in the first five blocks of titanium since the beginning of operation.
 Research methods. Metallographic, durometric, dilatometric.
 Results. With the help of dilatometric research, the coefficients of thermal expansion of samples of base steels – 14Х17Н13КМБх, and steels of the cladding layer – 10ХФТБх and 03Х17Н3Г9МБДЮч were obtained. As a result of research close to production conditions, a bimetallic workpiece was obtained, which is not subject to gouging, is crack-resistant and does not cause nickel to flow into the titanium sponge.
 Scientific novelty. On the basis of experimental data, the development of destruction of the inner surface of the reactors of the magnetothermal process for the production of sponge titanium, which is subjected to temperature, mechanical load and periodic contact with titanium tetrachloride, liquid magnesium and magnesium chloride, which leads to grooving, the appearance of cracks in the reactor and the inflow of nickel into the titanium sponge, has been established. It is shown that in order to eliminate these undesirable phenomena, it is necessary to use a bimetallic material of different chemical composition with similar structure and physical and mechanical properties: coefficient of thermal expansion, hardness and strength limit.
 Practical value. On the basis of research results, the chemical composition of the base – steel 14Х17Н13КМБч, cladding layer – steel 03Х17Н3Г9МБДЮч and the mode of hot deformation were developed, which made it possible to obtain the necessary structure, physico-mechanical and service properties.