Based on the Thermo-Calc thermodynamic software, the type of equilibrium precipitated carbides and their contents in high Mo Nb-microalloyed H13 steel （NMH13 steel） were calculated. The composition, morphology, and ...Based on the Thermo-Calc thermodynamic software, the type of equilibrium precipitated carbides and their contents in high Mo Nb-microalloyed H13 steel （NMH13 steel） were calculated. The composition, morphology, and distribution of carbides after spheroidal annealing of two forged experimental steels were comparatively examined by means of optical microscopy （OM）, scanning electron microscopy （SEM）, electron dispersive spectroscopy （EDS） and transmission electron microscopy （TEM）. VC, M23 C6 and M6C are identified in H13 steel after spheroidizing annealing, while （V,Nb）C, M23C6 , M2C and M6C are observed in NMH13 steel. Moreover, it is found that the ad- dition of Nb significantly enhances the stability of MC phase and the high Mo content accelerates the precipitation of small rod-shape M2C phase in NMH13 steel. The amount of the fine carbides in NMH13 steel obviously increased with M2 C and M6 C precipitated from the ferrite phase, which is in accordance with the results of thermodynamic cal- culations.展开更多
基金Item Sponsored by National High Technology Research and Development Program of China(2013AA031601)
文摘Based on the Thermo-Calc thermodynamic software, the type of equilibrium precipitated carbides and their contents in high Mo Nb-microalloyed H13 steel （NMH13 steel） were calculated. The composition, morphology, and distribution of carbides after spheroidal annealing of two forged experimental steels were comparatively examined by means of optical microscopy （OM）, scanning electron microscopy （SEM）, electron dispersive spectroscopy （EDS） and transmission electron microscopy （TEM）. VC, M23 C6 and M6C are identified in H13 steel after spheroidizing annealing, while （V,Nb）C, M23C6 , M2C and M6C are observed in NMH13 steel. Moreover, it is found that the ad- dition of Nb significantly enhances the stability of MC phase and the high Mo content accelerates the precipitation of small rod-shape M2C phase in NMH13 steel. The amount of the fine carbides in NMH13 steel obviously increased with M2 C and M6 C precipitated from the ferrite phase, which is in accordance with the results of thermodynamic cal- culations.
