Study on possibility of unification between the continuous casting and hot rolling processes

The purpose of the study is to examine the possibility of unification between the continuous casting and hot rolling processes from a point of view of a slab temperature.First，a mathematical model has been made to estimate the change in slab temperature from a meniscus to a crater-end as well as the growing process of shell thickness.Second，the temperature process of slab and the position of a crater-end have been calculated under various casting conditions.Also，the effect of the thermal insulator，the withdrawal velocity and cooling intensity at the secondary cooling zone on the slab temperature has been inspected to find out the optimal condition for producing slabs with a possibly high temperature.Third，we have built up a mathematical model such that the slab temperature change in the hot rolling process may precisely be assessed，and discussed whether or not the continuously cast slab is permissible to be hot-rolled directly.The main results clarified here are summarized as…More follows：The average temperature over the whole sectional area of a cast slab can be kept at 1200℃at the casting machine end，if the slab is soft cooled at the secondary cooling zone，and if the control of spray cooling zone in the slab-width direction as well as the size of thermal insulator equipped at the slab corner is appropriate for keeping the slab corner temperature as high as sible.Furthermore，we have found an optimal cooling condition such that the temperature history over the whole slab section may remain aloof from the hot embrittlement range at the unbending point.Next，we have examined whether or not the slab transported directly from the continuous casting machine can be rolled from the standpoint of temperature。The initial temperature at the first rougher is allowed to be lower as the bar thickness is increased.Its thickness more than 55 mm enables us to drop the initial hot rolling temperature necessary for producing 1.2 mm hot coils below 1200℃，keeping the final rolling temperature above the&lt；Ar_3&gt；critical point.In conclusion，we note that it is possible to unify the continuous casting and hot rolling processes directly on line.Less：Less

The purpose of the study is to examine the possibility of unification between the continuous casting and hot rolling processes from a point of view of a slab temperature. First, a mathematical model has been made to estimate the change in slab temperature from a meniscus to a crater-end as well as the growing process of shell thickness. Second, the temperature process of slab and the position of a crater-end have been calculated under various casting conditions. Also, the effect of the thermal insulator, the withdrawal velocity and cooling intensity at the secondary cooling zone on the slab temperature has been inspected to find out the optimal condition for producing slabs with a possibly high temperature. Third, we have built up a mathematical model such that the slab temperature change in the hot rolling process may precisely be assessed, and discussed whether or not the continuously cast slab is permissible to be hot-rolled directly.The main results clarified here are summarized as … More follows: The average temperature over the whole sectional area of a cast slab can be kept at 1200゜C at the casting machine end, if the slab is soft cooled at the secondary cooling zone, and if the control of spray cooling zone in the slab-width direction as well as the size of thermal insulator equipped at the slab corner is appropriate for keeping the slab corner temperature as high as possible. Furthermore, we have found an optimal cooling condition such that the temperature history over the whole slab section may remain aloof from the hot embrittlement range at the unbending point. Next, we have examined whether or not the slab transported directly from the continuous casting machine can be rolled from the standpoint of temperature. The initial temperature at the first rougher is allowed to be lower as the bar thickness is increased. Its thickness more than 55 mm enables us to drop the initial hot rolling temperature necessary for producing 1.2 mm hot coils below 1200゜C, keeping the final rolling temperature above the <Ar_3> critical point.In conclusion, we note that it is possible to unify the continuous casting and hot rolling processes directly on line. Less