The Optimization Of Solidification End Soft Reduction For Typical Low Carbon High Strength Steel Slab

The central segregation has a serious influence on the internal quality of steel.The central segregation can be reduced and the quality of slab can be improved by soft reduction at the solidification end of casting slab.The soft reduction position is directly related to the position of the solidification end.Aiming at the bulging phenomenon during cold bending of low carbon steel product by Handan steel.Component analysis showed that central segregation was the main reason of this defect.The solidified shell of q550 d slab was measured by nail shooting.The solidification model of heat transfer was established by Ansys software.Numerical simulation results were verified by using nail shooting results,and the reasonable position of soft reduction was obtained by simulation.By adjusting the parameters of soft reduction,the central segregation of the casting slab can be optimized,and then the problem of lateral bending defects can be solved.Main conclusions are as follows:(1)When the casting speed of q550 d steel is 0.80m/min,the end solidification position is 19.47 m,the simulation result is 19.79 m,the deviation is 0.32 m,the error is 1.64%.When the casting speed is 0.85m/min,the position of solidification end is 20.14 m,the simulation result is 20.80 m,and the deviation is 0.66 m,the error is 3.27%.(2)For every 10 ? increase in superheat degree,the surface temperature of secondary cooling zone end increases by 4.9 ?,the center temperature increases by 7.3 ?,and the corner temperature increases by 2.6 ?.The difference in width surface temperature caused by the change in superheat degree gradually decreases with the increase in meniscus distance,and the difference in center temperature starts to increase again after the full solidification of the casting slab,and the change in corner temperature of the casting slab is not significant.The change of casting speed has a great influence on the temperature.for every 0.10 m / min increase of casting speed,the surface temperature of secondary cooling zone end increases by 56.8 ?,the center temperature increases by 85.4 ?,and the corner temperature increases by 42.0 ?.The difference between the surface temperature of casting slab and the corner temperature increases with the increase of meniscus,and the center temperature does not change much before full solidification,but the temperature difference increases rapidly after solidification.(3)The influence of different casting conditions on the pressing position is analyzed.The results show that : The influence of superheat on the soft reduction position is small,the start position is 0.41 m backward for every 10? increase of superheat,and the pressing interval is slightly reduced;The casting speed has a great influence on the soft reduction position.Each 0.10 m/min increase in the casting speed,the soft reduction start position moves backward by 1.9m,and the soft reduction interval increases by about 0.7m.(4)The central segregation phenomenon of low-carbon high-strength steel in continuous casting process can be obviously optimized by optimizing the solidification end soft reduction process,and then the lateral bending deformation problem can be solved.The specific process adjustment is as follows: the soft reduction position is adjusted backward by one sector,from six,seven and eight segments to seven,eight and nine segments.The amount of soft reduction increased from 6.1 mm to 6.9 mm..