Institute of Metallurgical Machinery (Moscow, Russia):

Nikolaev G., Cand. Eng., Leading Scientifi c Fellow, 

Berkovich S. , Scientifi c Fellow,

Drozdov A., Deputy Head of Dept. omnlm@yandex.ru

The paper describes the results of comparative testings of mould shells of “VM-sinus” construction and shells with parabolic taper degree in continuous casting of tube billets with 150 and 156 mm diameter at Sinarsky Pipe Plant. Passed investigations have revealed several quality problems of the tube billets, connected with longitudinal cracks and rupturing. Testing of new mould shell construction, based on sine shape of upper part of the shell, has been conducted. Amplitude of this shape decreased along the mould length till transition area to a forming part, according to some definite rule. It is shown that parabolic curve describes shrinkage process of billets during their solidification in the most complete way. Six shells with 156 mm diameter have been fabricated at industrial equipment of the All-Russian Scientific and Research Institute of Metallurgical Machinery; they have the length of area of sine-shaped concavity as large as 300 and 325 mm. Quality of macrostructure (central porosity, axial segregation, general cracking, axial cracking) of the billets depending on steel grades are compared. As well, density of heat stream in the mould for different casting rates has been examined for the same seven steel grades. The results of testings have displayed that quality of billets made of crack-sensitive steel grades and cast in “VM-sinus” mould is rather better than quality of billets cast in the parabolic-shaped mould. It was also concluded that intensity of heat stream is higher in “VM-sinus” mould, while macrostructure, geometrical dimensions and billet out-of rounding corresponded to technical requirements for pipe billets.

1. Gankin V. B., Nikolaev G. I., Shifrin I. N. et al. Gilzovyy kristallizator dlya vysokoskorostnogo nepreryvnogo litya kruglykh zagotovok (Tube-type mold for high-grade continuous casting of round billets). Patent RF, No. 2308348. Published: October 20, 2007. Bulletin No. 29.