Mechanism of Oscillation Mark Formation in Continuous Casting of Steel

A new mechanism of oscillation mark formation has been suggested based on the deep investigation of meniscus behavior in continuous casting of steel. It's confirmed that the meniscus form is important to oscillation mark formation. The factors related to the formation of oscillation mark are discussed in detail. The longer the solid shell existed at the root of meniscus and the smaller the contact angle between meniscus and mold wall, the deeper the oscillation mark.

Formation and control of the surface defect in hypo-peritectic steel during continuous casting:A review

Hypo-peritectic steels are widely used in various industrial fields because of their high strength,high toughness,high processability,high weldability,and low material cost.However,surface defects are liable to occur during continuous casting,which includes depression,longitudinal cracks,deep oscillation marks,and severe level fluctuation with slag entrapment.The high-efficiency production of hypo-peritectic steels by continuous casting is still a great challenge due to the limited understanding of the mechanism of peritectic solidification.This work reviews the definition and classification of hypo-peritectic steels and introduces the formation tendency of common surface defects related to peritectic solidification.New achievements in the mechanism of peritectic reaction and transformation have been listed.Finally,countermeasures to avoiding surface defects of hypo-peritectic steels duiring continuous casting are summarized.Enlightening certain points in the continuous casting of hypo-peritectic steels and the development of new techniques to overcome the present problems will be a great aid to researchers.

Modification for prediction model of austenite grain size at surface of microalloyed steel slabs based on in situ observation

The initial solidification process of microalloyed steels was simulated using a confocal scanning laser microscope,and the growth behavior of austenite grain was observed in situ.The method for measuring the initial austenite grain size was studied,and the M_(0)^(*)(the parameter to describe the grain boundary migration)values at different cooling rates were then calculated using the initial austenite grain size and the final grain size.Next,a newly modified model for predicting the austenite grain size was established by introducing the relationship between M_(0)^(*)and the cooling rate,and the value calculated from the modified model closely corresponds to the measured value,with average relative error being less than 5%.Further,the relationship between T^(γ)(the starting temperature for austenite grain growth)and equivalent carbon content C_(P)(C_(P)>0.18%)was obtained by in situ observation,and it was introduced into the modified model,which expanded the application scope of the model.Taking the continuous casting slab produced by a steel plant as the experimental object,the modified austenite grain size prediction model was used to predict the austenite grain size at different depths of oscillation mark on the surface of slab,and the predicted value was in good agreement with the actual measured value.

The Research on Soft-Contacting Electromagnetic Continuous Casting in Baosteel

The paper introduces the research and new development on soft-contacting electromagnetic continuous casting in Baosteel.At the year of 2008,Baosteel successfully completed the carbon steel SCEMCC industrial experiment in a 6-strand curved type round billet caster.At the year of 2011,Baosteel selected another 3-strand curved billet caster. Baosteel successfully developed the SCEMCC mold for the first time to do the industrial production experiment for stainless steel round billet continuous casting.Then,in the same stainless steel caster,the square billet SCEMCC mold was successfully developed too.And at the beginning of the year 2012,the square billet SCEMCC of SUS304 and SUS303Cu was implemented up to now.It was proved the machine system was reliable for the long time production.The industrial experimental result shows the soft-contacting electromagnetic continuous casting can reduce the depth of oscillation mark from about 0.7mm to near zero.The SCEMCC billets without surface grinding were transferred to mill tubes,of which the quality is satisfied.