摘要:
直接轧制连铸坯切断后直接进入粗轧,没有加热炉加热过程,导致连铸坯温度场不均匀。通过有限元法对直接轧制连铸坯进粗轧机前的温度场以及直接轧制和传统轧制第一道次形变进行了数值模拟,结果表明:150 mm×150 mm连铸坯切断及之后的300 s内,连铸坯总体温度保持1 000℃以上的较高温度,可以实现直接轧制;直接轧制心部形变比传统轧制大,连铸坯心部比表面温度高,心表温差大有利于形变的渗透。进行了方坯直接轧制现场试验,验证了温度场模拟结果,同时对产品力学性能及时效进行试验,结果表明:方坯直接轧制连铸坯不均匀温度场导致了连铸坯各部位对应产品的性能差异;经时效试验,产品抗拉强度和屈服强度在20 MPa范围波动,变化的趋势不明显,断后延伸率在时效的前10天有明显升高。
Abstract:
The continuous casting square billets are directly transferred into rolling stands immediately after being cut off.An uneven temperature field occurs on the billet as a result of elimination of reheating step.The temperature field of billets being directly transferred into rolling line process and the first pass on direct rolling and conventionally rolling processes were investigated by finite element method.The results show that the average temperature of the 150 mm×150 mm billet within 300 s after being cutting off can still remain more than 1000℃,which is suitable for direct rolling.The reduction in the center of billet via direct rolling is bigger than that through conventional rolling.The results from industrially direct rolling test show a good agreement with the simulated result in terms of temperature field.The tensile test indicates scattered distribution of mechanical properties along the length of bar.After a period of 10-days aging,the change of yield strength and tensile strength along the length direction is in small range of 20 MPa,and total elongation increases obviously in the first ten days.
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