The Effects Of Continuous Casting Process Parameters On The Surface Depression And Oscillation Mark Of SWRM8 Billet

Cold forging steel is used for producing higher standardized parts and components with interchangeability, which have high demands for the quality of billet.The surface and internal defects of billet can easily lead to a crack in the following processing or become hard to forming. This paper aims at resolving the existing surface defects of the oscillation marks and the depression in the SWRM8 billet produced by the NO.1 Steel-making Plant of WISCO. Analysis on forming and influencing factor of processing parameters for oscillation marks and depression has been done, through building mathematical heat transfer model and mould flux channel dynamic pressure model of the billet. At last, the article proposes the improvement defects measures.Simulation and analysis show: (1)The billet surface temperature distribution from the corner to the centre is rapidly increasing at first, and then stabilize in the process of billet casting. The highest temperature point occurs in the billet side area between 20 to 40mm distances, where the billet shell grow slowly, become thinner, So it is the weak area of the entire cross-section. The shrinkage force and the static pressure of molten concentrate both make the depression form. In the second-cooling area, the curve of billet temperature looks like wave. The strong thermal stress and the others stress all together makes the depression expand, that could engender crack or other flaws. (2)The mould flux channel pressure measures presents periodic change in the process of mould oscillation. When oscillation enters the negative strip time, the flux channel starts to be under the positive pressure. When the positive pressure is stronger than the static pressure of liquid steel, the initial solidification shell is pushed out of the mould wall. The oscillation mark becomes deeper with the increasing positive pressure and negative strip time that cause initial solidification shell being curved much.According to the simulation results, some suggestions have been proposed in order to solve the oscillation marks and the depression in the SWRM8 billet as follows: Controling the carbon content of molten steel below 0.08%, the superheat in about 30℃, the pulling speed at 1.6m/min, adopting medium cooling intensity, increasing the frequency of oscillation, reducing the amplitude of oscillation, and using the high frequency and small amplitude oscillating mode as h=3Vc,f=-10Vc+190.