Slow-cooling temperature control device for stainless steel slabs and control method

Abstract

The invention pertains to the technical field of metallurgy material, in particular to a slow-cooling temperature control device for stainless steel slabs and a control method.In a slow-cooling pit, temperature in the pit changes periodically within the range from 350 to 900 DEG C. In the way that temperature of the slow-cooling pit and slow-cooling speed of slabs are controlled by recirculation furnace gas, the slabs are uniformly cooled. The slow-cooling temperature control device for the stainless steel slabs and the control method have following beneficial effects: temperature of the stainless steel slabs in the slow-cooling pit is more uniform during a cooling process; internal stress produced from a cooling process of the slabs is decreased; occurrences of stainless steel slab cracks are effectively avoided; slow-cooling time of the stainless steel slabs in the slow-cooling pit is reduced by more than 20 %; slow-cooling productivity of the slabs is improved; and purposes of uniformly decreasing temperature of the stainless steel slabs in the slow-cooling pit at the front period and the late period of the slow-cooling pit are fulfilled.

Description

technical field [0001] The invention belongs to the technical field of metallurgical materials, and in particular relates to a slow cooling temperature control device and a control method for stainless steel slabs. Background technique [0002] Compared with carbon steel slabs, stainless steel slabs have phase changes in the cooling process, and some stainless steel slabs after continuous casting need to be cooled slowly to avoid internal cracks during the slab phase transition process. , In order to increase the hot charging temperature of the slab, uniform the furnace temperature, and avoid large fluctuations in the temperature of the slab into the furnace, a slow cooling pit is generally installed on the stainless steel rolling production line. In the production process of stainless steel slabs, the high-temperature slabs coming out of the continuous casting machine are cooled by the conveying roller table, and the cross-sectional temperature difference is relatively larg...

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Problems solved by technology

[0006] (1) During the slow cooling process of stacked slabs, the temperature of the upper slab drops faster, the temperature of the bottom slab drops slower, the temperature of the four corners of the slab drops faster, and the temperature of the middle of the slab drops slower, resulting in the same stack of slabs After the slab is slowly cooled in the slow cooling pit, the temperature difference between different positions of the slab and different points of the same slab is relatively large;

[0007] (2) It is difficult to control the temperature drop rate of the slab during the slow cooling process. The temperature of the slab is higher in the early stage of slow cooling, and the heat dissipation of the slab is mainly radiation heat transfer, and the temperature drop rate is faster; The temperature is low, the heat dissipation of the slab is mainly convective heat transfer, and its temperature drop rate is slow, resulting in a large difference in the temperature drop rate of the slab before and after cooling during the slow cooling process; although in the slow cooling process of the slab, adopt The furnace temperature is controlled by the opening of the pit cover, but this method can only be used when the cooling rate drops in the later stage of slow cooling of the slab, and in the early stage of slow cooling of the slab, when the pit cover is completely closed and the temperature drop rate is slower When it is fast, this method cannot control the temperature drop rate of the slab;

[0008] (3) During the slow cooling process of the slab, the temperature of the furnace gas in the pit and the temperature of the slab are not uniform, which has a great influence on the quality of the slow cooling of the slab. At the same time, when the slowly cooled slab is sent to the heating furnace for heating, Due to the large difference in the cross-sectional temperature of the billet, it is difficult to uniformly heat the billet in the heating furnace, and it has a certain impact on the rolling of the billet;

[0009] (4) For martensitic or ferritic stainless steel, it generally takes more than 48 hours for the slab to be slowly cooled from 800 to 900 °C to below 350 °C in the slow cooling pit, and at the same time, the internal stress of the slab is relatively large and cracks are easy to occur

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