Effect of casting process on the inner-wall band segregation of high-strength antisulfur pipes

Controlling inner-wall band segregation is one of the difficulties in the production of high-strength antisulfur pipes.Comparative tests were carried out on different casting processes(superheat,mold electromagnetic stirring,end electromagnetic stirring,casting speed and soft reduction)for the smelting of high-strength antisulfur pipes.The microstructures of continuous-casting billets and hot-rolled or tempered pipes were analyzed using a metallographic microscope and scanning electron microscope.The mechanism and evolution law regarding the inner-wall band segregation of high-strength antisulfur pipes were studied,and the influence of different casting processes was explored.

Effect of mold electromagnetic stirring on solidification structure and solute segregation in continuous casting bloom

The effect of mold electromagnetic stirring(M-EMS)on the solidification structure and solute segregation in the continuous casting bloom of U78CrV steel is investigated.The solute distribution in the macroscale is analyzed using a carbon–sulfur analyzer and that in the microscale is measured with an electron probe microanalyzer.The Image-J software is applied to analyze the number density and area ratio of segregation spots.The results show that the segregation spots are mainly located in the columnar to equiaxed transition zone and the equiaxed zone,which are enriched with C,Cr,and Mn elements.With the M-EMS applied,the columnar grain inclines to the upstream side.As the current intensity increases,the deflecting angle of columnar grain rises,especially with the current intensity larger than 300 A.Besides,the center segregation shows a declining trend and the area fraction of the equiaxed zone rises clearly.Moreover,it is found that the area ratio and number density of segregation spots increase with the higher current intensity of M-EMS.