稀土元素对耐候钢元素偏析的影响

应用金属原位统计分布分析技术(OPA)研究了耐候钢铸锭中C、P、S、Cu、Si和Mn的宏观偏析规律,并分析了稀土元素对耐候钢中元素偏析的影响.结果表明,在30%～40%等轴晶率,20℃过热度下,元素C、S、P和Cu能产生严重的宏观偏析,C、S呈中心正偏析,P、Cu呈中心负偏析并伴随有反偏析,而Si和Mn的分布较为均匀.各个元素中心偏析位置完全相同.稀土元素在钢中的固溶度为10-5～10-4,固溶稀土元素可以细化枝晶,提高等轴晶率.钢中加入质量分数0.38%～0.55%的稀土元素可以有效改善C、S、P和Cu的宏观偏析.

Effect of rare earth elements on macrosegregation in weather-resisting steel

The macrosegregation of C, P, S, Cu, Si and Mn in cast ingots of weather-resisting steel was studied by applying the technology of original position statistic distribution analysis (OPA), and the effect of rare earth elements (RE) on the macrosegregation in the steel was analyzed. The results showed that under the condition of the equiaxial crystal rate of 30% to 40% and the overheating temperature of 20 ℃ in the ingot, there was serious macrosegregation of C, S, P and Cu in the steel. C and S present center positive segregation, P and Cu the center negative segregation, and P and Cu the inverse segregation, while the solute distributions of Si and Mn were more uniform. The segregated zone of each element was of exactly the same. The solid solubility of RE in the steel were 10~(-5) to 10~(-4), and the soluted RE could refine dendrites and increase the equiaxial crystal rate. The macrosegregation of C, P, S and Cu was improved obviously by adding RE of 0.38% to 0.55% into the steel.