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利用电子探针对实验室以及工厂冶炼的低碳Fe-25Mn-3Si-3Al TWIP钢的显微偏析进行系统性检测.结果表明:该TWIP钢的实验室铸锭和工厂AOD电极锭具有明显的枝晶偏析,其中AOD电极锭的偏析程度更高,Mn和Al的最大偏析量分别高达6.8%和2.4%;AOD电极锭经电渣重熔后晶界偏析显著,偏析程度并没有得到明显减轻;最后经工厂高温锻造成型后的锭坯中晶界偏析得到改善.合金成分高和结晶温度间隔宽是产生较大显微偏析的主要原因.该TWIP钢的所有试样均呈相同的偏析规律,Mn为负偏析,Al和Si呈正偏析,且Al的偏析程度最高.通过Thermo-Calc对该TWIP钢的溶质分配系数进行计算,发现Mn和Al理论预测的显微偏析规律与实验所得的规律完全相反.通过实验验证,得出Si含量是影响Mn和Al偏析规律的决定性因素.
The microscopic segregation of low-carbon Fe-25Mn-3Si-3Al TWIP steel refined by laboratory and factory was systematically investigated by electron probe.The results showed that the laboratory ingot and factory AOD electrode ingot of TWIP steel had obvious Dendritic segregation, in which AOD electrode segregation degree is higher, the maximum segregation amount of Mn and Al are as high as 6.8% and 2.4%; AOD electrode ingot after ESR grain boundary segregation was significant, segregation degree has not been significantly reduced ; Finally, the segregation of grain boundaries in the billets after high-temperature forging molding in the plant is improved. The high alloy composition and the wide crystallization temperature interval are the main reasons for the larger microsegregation. All samples of the TWIP steel show the same segregation law , Negative segregation of Mn, positive segregation of Al and Si, and the highest degree of segregation of Al. The solute partition coefficient of TWIP steel was calculated by Thermo-Calc and found that the rule of microsegregation predicted by Mn and Al theory and experimental rule On the contrary, we conclude that the content of Si is the decisive factor affecting the segregation of Mn and Al through the experimental verification.