Magnitogorsk State Technical University named after G. I. Nosov, Chair of Metal Forming:

V. M. Salganik, Dr. Eng., Professor, Head of Chair

A. M. Pesin, Dr. Eng., Professor, pesin@bk.ru

D. N. Chikishev, Ph.D, Professor Assistant

D. O. Pustovoitov, Ph.D, Assistant

M. O. Artamonova, Student

This paper presents the numerical analysis of characteristics of the rolling of the slab with surface longitudinal and transverse axial cracks. Different kinds of surface cracks in continuously cast slabs are analyzed and typical kind of longitudinal axial crack is presented. Finite element models of slabs with longitudinal and transversal axial cracks are observed. It is shown that during rolling are the most unfavorable conditions of deformation at which the crack surface is oriented perpendicular to the rolling direction. In this case the disclosure of a defect is occurred under high tensile stress. Taking into account the fact that longitudinal axial cracks are the most frequent in continuous casting of micro-alloyed tube steels, it is shown that to reduce the formation and development of the defect, "rolled out a crack" in the rolling plate mill designed to rational modes of deformation. They include increase of deformation degree during the first pass and/or rolling with two passes and total reduction 30-34%. It is also recommended to minimize elongation ratio with choosing slab of maximal width; additionally, rolling in the first passes should be conducted with small reduction (10-12%), while in the last passes - with more large reduction (14-18%).

1. Takashi I., Nobuki Y., Yoshinori Y. Deformation Analysis of Surface Defect on Plate Rolling.  Tetsu to  Hagane. 2003. V. 89. P. 1142–1149.

2. Kainz A., Parteder E., Zeman K.  From Slab Corner Cracks to Edge-Defects in Hot Rolled Strip — Experimental and Numerical Investigations. Steel Research International. 2008. Vol. 79. P. 861–867.

3. Pesin A., Salganik V., Pustovoitov D. Modeling of Surface Crack Form Change of Continuously Cast Slabs in Roughing Rolling at Wide Strip Mill 2000. Proceedings of the 13^th International Conference on Metal Forming METAL FORMING 2010, Toyohashi, Japan, September 19–22, 2010. — Toyohashi, 2010. P. 82–86.

4. Pesin A., Salganik V., Pustovoitov D. Transverse crack modeling of continuously casted slabs through finite element method in roughing rolling at wide strip mill. Proceedings of the 10^th International Conference on Numerical Methods in Industrial Forming Processes NUMIFORM 2010, Pohang, Republic of Korea, June 13–17, 2010. — Pohang, 2010. P. 1309–1315.