Abstract
Surface cracking seriously affects the quality of beam blanks, a relatively new blank in the continuous casting in China. In order to study the mechanism of the initiation and propagation of surface cracks, this study established a 2D micro-segmented model of the solidification process for a beam blank in the mold, with a user subroutine DFLUX written in Fortran. Using a contact algorithm, the stress in the shell of the beam was analyzed considering the mechanical properties of the material (Q235B), thermal stress, surface friction force and ferrostatic pressure. The results showed that at the center of the web, surface longitudinal cracks were most likely to initiate at a height of 180 mm from the meniscus; at the fillet, surface longitudinal cracks were most likely to initiate at a height of 200 mm from the meniscus. Moreover, the casting speed showed a greater effect on surface crack initiation than the pouring temperature did. This study reveals the cause of longitudinal crack initiation, and the most likely positions of cracks on the strand. Thus, it is instructive for controlling surface cracks in production.
Highlights
IntroductionThe main factors causing the occurrence of surface cracks in the shell of the beam blanks during continuous casting are the heterogeneous distributions of stress and temperature in the shell
The main factors causing the occurrence of surface cracks in the shell of the beam blanks during continuous casting are the heterogeneous distributions of stress and temperature in the shell.Compared to a normal slab, as a near-net shape, the cross-section of the beam blank is more complex, and the stress and temperature distributions are more uneven
The contours show that the surface temperature of the blank gradually decreases as the strand moves downwards; at the exit of the mold, the temperature entire beam blank gradually decreases as the strand moves downwards; at the exit of the mold, the distribution is uneven, with the lowest and highest temperatures occurring at the flange tip and fillet, temperature distribution is uneven, with the lowest and highest temperatures occurring at the flange respectively
Summary
The main factors causing the occurrence of surface cracks in the shell of the beam blanks during continuous casting are the heterogeneous distributions of stress and temperature in the shell. FEM coupled thermo-elastic-plastic tothe compute the and stress contours in the continuous casting of a steel beam blank and found that cracks were temperature and stress contours in the continuous casting of a steel beam blank and found that generated the web and the tips. They proposed an optimum discovering that high heat flow was the critical factor in surface crack formation on the web. The studies above helpful forwhen enhancing thea quality of beam formed by continuous casting Mostcould of these studies havereduced concentrated on adjusting continuous-casting of δ-Fe to γ-Fe occur, which the heat flux and the induced longitudinal process surface parameters.
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