对含铌0.051％的H13钢铸锭中一次碳氮化物成分特征及在1150℃、1250℃下的热稳定性进行了分析,并利用热力学软件Thermoo-Calc对其形成机制进行了合理的解释.研究发现含铌0.051％的H13钢铸锭中存在3类一次碳氮化物,富Nb类、富v类以及富Mo-Cr类相.富Nb相热稳定性高,在1150℃及1250℃下保温6h仍大量存在.富V相在1150℃下保温6h仍然存在,而在1250℃下保温6h即可完全固溶.富Mo-Cr相热稳定性低,无论是在1150℃还是1250℃下,均没有发现.这些相是在凝固过程中由于元素富集而在液相中析出.凝固过程中,富V的碳氮化物相首先析出,之后随着Nb含量的富集,富Nb的碳化物相开始析出,当Nb元素消耗到一定程度而同时V元素进一步富集后,富V的碳化物相再次析出,富Mo-Cr相在凝固末期最后析出.
The composition characteristics and thermal stability at 1150 ℃ and 1250 ℃ of large primary carbonitrides in H13 ingot modified with 0.051％ Nb were studied.The formation mechanism of these carbonitrides was analyzed by Therml-Calc software.The results show that three types of primary carbonitrides exist in the Nb-containing H13 ingot,which is,Nb-rich ones,V-rich ones and MoCr-rich ones.Nb-rich carbonitrides are stable after holding at 1150 ℃ and 1250 ℃ for 6 h,while V-rich phases can dissolve totally at 1250 ℃.Mo-Cr-rich carbonitrides are unstable at high temperature and are not observed at 1150 ℃ and 1250 ℃.These carbonitrides are generated in the liquid steel during solidification due to the elements segregation.During solidification,V-rich carbonitrides precipitate firstly,after which Nb-rich phase can precipitate with the enrichment of Nb in liquid steel.When Nb is consumed to a certain extent,Vrich carbides appear again.Mo-Cr-rich phase precipitates at the end of solidification.
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