The effect of water ratio in secondary cooling zone on billet cooling speed, solidification structure and center carbon segregation index of 0.64% - 0.82%C steel 150 mm×150 mm billet casting with 250A/5Hz electromagnetic stirring has been tested.
The microscopic structure and CCT curve of 20MnSi and 20MnSiV in different cooling speed conditions were obtained through double compression deformation in the thermal simulation machine of Gleeble-1500.In addition,the effect of Vanadium on the structure and CCT curve of 20MnSi steels are also described by comparing the microscopic structure and CCT curves.
Based on these results the optimum controlled cooling process is that after finished rolling 45 steel bar is cooled to 750℃ at the cooling rate of 10℃ /s and then to 680℃ at extremely slow cooling speed (over one hour ).
2.The thermal force test indicate that network carbide can be eliminated at the cooling speed is 5℃ per second at the final rolling temperature of 900℃, and network carbide can be eliminated at the cooling speed of 3℃ per second and final rolling temperature of 850℃.
Optimum conditions of the Czochralski-pulling procedure are that the pulling speed is 0. 5-4 mm/h, the rotation rate 10-18r/ min, the cooling speed 18 ℃/h and the axial temperature gradient in solid-liquid interface 0. 7-1 ℃/mm.
Yb∶NaY(WO_(4))_(2) were grown by the Czochralski method. The optimum parameters for crystal growth are described as the pulling speed 0.5-4 mm/h, the rotation rate 30-40 r/min, the cooling speed 18 ℃/h.
In the final system, the stable accuracy of temperature is 0.3℃, the heating speed is 8℃/s and the cooling speed is 12℃/s. It shows that the control system has good tracking ability and the demand of gene-chip preparation is fully met.
After the system to be used, the cooling speed of steel plate can be quickened, in the premise that the properties of steel plate are not infected basically, the quantity of production can be enhanced largely.