Research On The Formation Mechanism Of Oscillation Marks In The Continuous Casting Of Steel Slabs

In continuous casting,oscillation marks is the main reason that leads to slabs’cracksand segregation,with the quality of the slab reducing. herefore, it is the study on theformation mechanism of oscillation marks and quantitative analysis on the depth ofoscillation marks that helps to improve casting quality,which is significant greatly.A new mechanism of oscillation marks is proposed.The theory said that friction thatmold and solidified shell caused leads to the deformation of solidified shell,During thenegative slide time,when the solidified shell was deformed, liquid steel overflow andposted to the mold wall.Under the action of surface tension,a small meniscus takeshape.the friction result in an oscillation marks for one cycle.A small meniscus’s equation and the the function curve of relationship between thetheoretical oscillation mark depth and the amound of solidifice shell’s downwarddeformation was calculated through force analysis.Theoretical results show that the depthof oscillation marks rely on the amount of the solidified shell’s downward deformationand the amount of the bend about the initial freezing point.A two-dimensional thermal model about slab and copper was established,whichstudied that with the casting speed changing, the solidificative characteristics of themeniscus.the result point out that there is some part of solidification at the meniscusarea.With casting speed increasing,the amount of the bend about the initial freezing pointis decreasing generally.it will mitigate oscillation marks.thus it is better that casting speedshould be controlled to more than1.0m/min generally.According to copper mold and slab temperature resultes,this paper calculated thedistribution and amount of liquid friction,mixed friction and solid friction at the center ofwide surface.The result show that since the temperatute at the center of the wide surfaceis high,the proportion of the liquid friction is the largest and the proportion of the solidfriction smallest.it is in line with the actual situation.A two-dimensional mechanical model about the slab is established,and using it analysis how friction effects the amount of steel shell deformation,and then the disciplinebetween the amount of deformation of the solidified shell and two vibration parameters——amplitude and frequency.comparing variation curves obtained two discipline——thehigher the amplitude,the more the amount of the solidified shell deformation,the deeperthe oscillation marks,and the larger the frequency,the smaller the amount of the solidifiedshell deformation,the more shallow the oscillation marks.Comprehensive analysis showthat when the amplitude is3mmand the frequency is180r/min, the amount of thesolidified shell deformation is0.26mm.This describe that when this parameter ischoosed,the oscillation marks is shallow and the quality of the slab is high.According to the analysis, on the one hand, the cause of the phenomenon that theshorter the negative time,the more shallow the oscillation marks is explained,and thenew mechanism of oscillation marks is verified. On the other hand, the vibrationparameters that improved oscillation marks were optimized, which will help to obtain thereasonable vibration parameters and effectively increase the quality of the slab.