Abstract：GCr15SiMn bearing steel ingots,which were cast after smelting in vacuum induction furnace,were investigated by original position statistic distribution analysis.The effects of degree of superheat on elemental segregation (C,Si,Mn and Cr) and porosity of ingot were analyzed.The results showed that:when the degree of superheat was relatively low (25 ℃),the obvious segregation and cavity shrinkage occurred at the end of solidification due to the large numbers of nucleation of solute elements in the front of solidification and the thermal convection difference of molten steel.The statistical segregation and statistical porosity of C was 7.83% and 1.76%,respectively.With the further increase of superheat (55 ℃),the heat convection of molten steel was strengthened,and the segregation of elements was improved to some extent.The statistical segregation and statistical porosity of C in ingot reached the minimum,i.e.,4.06% and 1.34%, respectively.When the superheat was relatively high (75 ℃ and 105 ℃),the thermal convection of the molten steel was strong.The solute elements floated up, which deteriorated the segregation and porosity at the solidification end of the ingot.Therefore,through the quantitative analysis of segregation and porosity of the ingot, the degree of superheat at 55 ℃ was the optimal process parameter for casting.
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