Evaluation and improvement of pearlite microstructure and mechanical properties in 45Cr4NiMoV and 50Cr5NiMoV steels  

作　　者：Kai-quan Liu Xue-jiao Zhang Xiao-yang Song Lin Zhao Lin Zhu 

机构地区：[1]State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,Qinhuangdao 066004,Hebei,China [2]Tianjin Heavy Industries Research&Development Co.,Ltd.,CFHI,Tianjin 300457,China [3]China First Heavy Industry,Qiqihar 161042,Heilongjiang,China [4]Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China

出　　处：《Journal of Iron and Steel Research International》2022年第12期1995-2005,共11页

基　　金：This work was financially supported by the Major Science and Technology Program of Heilongjiang Province(Grant No.2019ZX10A02).

摘　　要：The microstructure and mechanical properties of pearlite in 45Cr4NiMoV and 50Cr5NiMoV steels were studied and compared.The microstructural characteristics of pearlite of two steels were carefully examined by optical microscopy,scanning electron microscopy and transmission electron microscopy(TEM),and the type,size and relative amount of extracted carbide particles were analyzed by X-ray diffraction and TEM coupled with selected area electron diffraction.The hardness,tensile property,impact and fracture toughness of pearlite of two steels were also evaluated.Besides,the carbide dissolution kinetics of 45Cr4NiMoV and 50Cr5NiMoV steels were clarified.The results indicated that the carbides in 50Cr5NiMoV steel exhibited higher dissolution temperature than those in 45Cr4NiMoV steel,which induced different morphologies of pearlite after eutectoid transformation.Compared to the pearlite with lamellar M_(23)C_(6)carbides in 45Cr4NiMoV steel,the pearlite with the mixture of spheroidized M_(7)C_(3)and lamellar M_(23)C_(6)carbides in 50Cr5NiMoV steel possessed higher impact and plane-strain fracture toughness but lower hardness and strength,because different pearlite morphologies led to different mechanical properties.In order to further improve the comprehensive properties of the steels,the fraction of M_(7)C_(3)for the material with acceptable properties was examined and dissolution kinetic of M_(7)C_(3)was calculated.Therefore,the austenitizing temperature and holding time could be appropriately selected to keep enough undissolved M_(7)C_(3)in the steels.

关 键 词：Microstructure CARBIDE Back-up roll Mechanical property TOUGHNESS SPHEROIDIZATION 

分 类 号：TG14[一般工业技术—材料科学与工程]