Study on primary carbides precipitation in H13 tool steel regarding cooling rate during solidification  

作　　者：Guang-di Zhao Xi-min Zang Wan-ming Li Zhuo Zhao De-jun Li 

机构地区：[1]School of Materials and Metallurgy,University of Science and Technology Liaoning,Anshan 114051,China [2]State Key Laboratory of Marine Equipment and Applications,Anshan,114051,China

出　　处：《China Foundry》2020年第3期235-244,共10页中国铸造（英文版）

基　　金：the National Natural Science Foundation of China(Grant No.51904146);the Doctor Start-up Fund of Liaoning Province(Grant No.2019-BS-125);the National Key Laboratory of Marine Engineering of China(Grant No.SKLMEA-USTL-201707)。

摘　　要：This study aims to investigate the primary carbides precipitation in H13 steel solidified at relatively high cooling rates,ranging from 300 to 6,000℃·min^-1,based on in situ observations with a high temperature confocal laser scanning microscope.In the cooling rate range investigated,the solidification microstructure becomes more refined as cooling rate increases and the relationship between the secondary dendrite arm spacing(SDAS),λ2,and cooling rate,.T,can be expressed asλ2=128.45.T-0.124.Regardless of cooling rates,two kinds of primary carbides,i.e.,the Mo-Cr-rich and V-rich carbides,are precipitated along the interdendritic region and most of them are the Mo-Cr-rich carbides.The morphology of Mo-Cr-rich carbide is not obviously influenced by the cooling rate,but that of V-rich carbide is obviously affected.The increasing cooling rate markedly refines the primary carbides and reduces their volume fractions,but their precipitations cannot be inhibited even when the cooling rate is increased to 6,000℃·min^-1.Besides,the segregation ratios(SRs)of the carbides forming elements are not obviously affected by the cooling rate.However,compared with the conventionally cast ingot,the SDAS and primary carbides in the steel solidified at the investigated cooling rates are much finer,morphologies of the carbides have changed significantly,and SRs of the carbides forming elements are markedly greater.The variation of primary carbide characteristics with cooling rate is mainly due to the change in SDAS.

关 键 词：H13 steel cooling rate SOLIDIFICATION primary carbides 

分 类 号：TG142.45[一般工业技术—材料科学与工程]