Method for healing triangular zone cracks during unsteady casting billet rolling
A technology of rolling process and triangular area, which is applied in the field of metallurgical rolling, can solve problems such as internal crack defects, rejection, and large variation range of casting slabs, and achieve the effects of eliminating influence, improving yield, and improving production efficiency
Inactive Publication Date: 2018-10-23
SHANGHAI MEISHAN IRON & STEEL CO LTD
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Problems solved by technology
During unsteady casting, the casting speed changes frequently and the range of change is large, so that the thickness of the solidified shell and the surface temperature of the slab change greatly. Improper control can easily cause internal crack defects in the slab, such as triangular cracks, central cracks and middle cracks. Cracks, this type of quality problem affects the yield of the billet, resulting in the billet having to be downgraded or scrapped
Method used
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Embodiment 1
[0024] Embodiment 1: see figure 1 , a method for healing triangular cracks in an unsteady-state slab rolling process, said method comprising the following steps, 1) contact heat transfer between a rolled piece and a roll, and the contact heat transfer relationship between the rolled piece and the roll is as follows :
[0025] q=hr(T s -T r )
[0026] In the formula, q is the heat flux density, W m -2 ; hr is the heat transfer coefficient between the rolled piece and the roll, W m -2 ·℃ -1 ; T s is the surface temperature of the rolled piece, °C; T r is the roll temperature, °C;
[0027] 2) During the rolling process, the radiation heat transfer between the rolled piece and the air is mainly considered;
[0028]
[0029] In the formula, ζ(T s ) is the surface emissivity of the object; τ is the Boltzmann coefficient, W / (m 2 ·K 4 );
[0030] 3) Extrusion heat. During the rolling process, the deformation of the rolled piece will also generate a certain amount of ex...
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The invention relates to a method for healing triangular zone cracks during unsteady casting billet rolling which comprises the following steps: 1) performing contact heat transfer between a rolled piece and a roller, wherein the expression of relation of the contact heat transfer between the rolled piece and the roller is in the description, wherein q is the heat flux, W.m<-2>; Hr is the heat transfer coefficient between the rolled piece and the roller, W.m<-2>.DEG C<-1>; Ts is the surface temperature of the rolled piece, DEG C; Tr is the roller temperature, DEG C; 2) in the rolling process,mainly considering the radiation heat exchange between the rolled piece and air, (please see the expression in the description), wherein. zeta(Ts) is the surface emissivity of an object; tau is Boltzmann coefficient, W / (m<2>.K<4>); 3) generating extrusion heat, wherein during the rolling process, the stressed deformation of the rolled piece will also generate certain extrusion heat, (please see the expression in the description), wherein Q is the heat of extrusion deformation; eta is the efficiency of heat generation during deformation; K is a constant; epsilon is the strain rate; M is the strain rate sensitivity coefficient; 4) setting boundary conditions through step 1)-3) to establish a corresponding finite element model.
Description
technical field [0001] The invention relates to a method for healing cracks in a triangular area during unsteady billet rolling, and belongs to the technical field of metallurgical rolling. Background technique [0002] Nowadays, many researches on continuous casting are aimed at steady state, but there are few researches on unsteady state. Casting processes such as ladles belong to unsteady casting. During unsteady casting, the casting speed changes frequently and the range of change is large, so that the thickness of the solidified shell and the surface temperature of the slab change greatly. Improper control can easily cause internal crack defects in the slab, such as triangular cracks, central cracks and middle cracks. Cracks, this type of quality problem affects the yield of the slab, resulting in the slab having to be downgraded or scrapped. [0003] Due to unsteady casting, triangular area cracks frequently appear in the slab, and the triangular area crack is a dang...
Claims
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IPC IPC(8): G06F17/50
CPCG06F30/23
Inventor 汪洪峰
Owner SHANGHAI MEISHAN IRON & STEEL CO LTD