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针对目前微合金钢凝固过程中产生大量裂纹缺陷的现状。以B-F偏析模型为基础对微合金钢凝固过程进行了理论分析,并结合Gleeble-1500热模拟试验,系统研究了SAPH440微合金钢凝固前沿脆性区的溶质偏析及裂纹敏感性。结果表明:微合金钢凝固过程中,固相率在0.75～1.00之间时,C、Mn元素偏析较轻,S、P、Ti元素偏析严重,Mn对S偏析有抑制作用,Mn的质量分数增加到1.2%时,S的偏析度降低至20.7;对凝固脆性区的影响程度顺序为Mn>S>C>P>Ti,S的质量分数由0.002%增加至0.02%,凝固脆性区由25K扩大至33K;Mn的质量分数从0.2%增大到1.6%时,裂纹敏感区间由15K扩大至38K。同时Gleeble-1500热模拟试验证实钢脆化的原因与试样的凝固组织无直接关系。
Aiming at the current situation of a large number of crack defects during the solidification of microalloyed steel. Based on the B-F segregation model, the solidification process of microalloyed steel was theoretically analyzed. In combination with Gleeble-1500 thermal simulation, the solute segregation and crack susceptibility of SAPH440 microalloyed steel in the frontal brittleness zone were systematically investigated. The results show that the segregation of C and Mn elements is lighter and the segregation of S, P and Ti elements is serious when the solid fraction is between 0.75 and 1.00. The Mn segregates with S, the mass fraction of Mn When the content of S increased, the segregation degree of S decreased to 20.7. The order of influence on the brittleness zone was Mn> S> C> P> Ti. The mass fraction of S increased from 0.002% to 0.02% To 33K. When the mass fraction of Mn is increased from 0.2% to 1.6%, the crack-sensitive zone is expanded from 15K to 38K. At the same time, Gleeble-1500 thermal simulation test confirmed that the cause of steel embrittlement has no direct relation with the solidified structure of the sample.