Research on the solidified microstructure and segregation behaviors of the UNS N10276 alloy produced by electroslag remelting

摘要

In this study,the solidified microstructure and segregation behaviors of the alloying elements and precipitate behaviors of the UNS N10276 alloy in a large-scale electroslag remelting(ESR)ingot were studied.Further,the formation of the solidified microstructure and segregation of ESR were systematically analyzed via thermodynamic calculations.The ESR ingot of the UNS N10276 alloy exhibits a typical dendritic structure.The secondary dendrite spacing at the head of the ingot is clearly larger than that at the bottom of the ingot.The alloying elements(e.g.,Mo,Mn,Si,and C),which are positive segregation elements,segregate to the interdendritic zones during the solidification process.However,Fe,W,and Cr segregate to the dendritic trunk zones,indicating that they are negative segregation elements.Among the alloying elements,Mo segregates the most,especially at the head of the ESR ingot.Majority of the precipitates that precipitate in the interdendritic zones and at grain boundaries belong to large-scale μ and M6C phases,respectively.Mo is the main element of the precipitates.The precipitates at the head of the ESR ingot are more abundant and larger than those at the bottom of the ingot.Hence,to improve the metallurgical quality and hot working properties of the UNS N10276 alloy,the segregation of the Mo element should be minimized,whereas the formation of the precipitates should be reduced as much as possible during the optimization of the composition and production processes.