Effect of Nb addition on microstructure and mechanical properties of 25CrNiMoV(DZ2)steel for high-speed railway axles  

作　　者：Jin-wen Zhang Yan-guang Cao Cheng-guo Zhang Zhao-dong Li Wen-xian Wang 

机构地区：[1]College of Materials Science and Engineering,Taiyuan University of Technology,Taiyuan,030024,Shanxi,China [2]Technology Center,Taiyuan Iron and Steel(Group)Co.,Taiyuan,030003,Shanxi,China [3]Department of Structural Steels,Central Iron and Steel Research Institute,Beijing,100081,China [4]Locomotive and Car Research Institute,China Academy of Railway Sciences Corporation Limited,Beijing,100081,China

出　　处：《Journal of Iron and Steel Research International》2022年第5期802-809,共8页

基　　金：supported by National Key R&D Program of China(No.2017YFB0304600).

摘　　要：The microstructure,precipitates and properties of 25CrNiMoV(DZ2)steel for high-speed railway axles with different Nb contents were investigated by means of optical microscopy,scanning electron microscopy,electron back-scattering diffraction,transmission electron microscopy and physicochemical phase analysis.The results show that the grain size of the original austenite of the test steels decreases from 20.5 to 14.2 and 10.8μm after adding 0.026 and 0.039 wt.%Nb to a 25CrNiMoV steel,respectively.Moreover,the block width of the tempered martensite in the test steels is refined from 1.91 to 1.72 and 1.60µm,respectively.MC-type precipitates in 25CrNiMoV steel are mainly VC,while(Nb,V)C gradually precipitates when Nb is microalloyed,and the amount of precipitates increases with increasing Nb content.Through strengthening mechanism analysis,it is found that grain refinement strengthening is the primary way to increase the strength.The improvement in the yield strength with increasing Nb content is attributed to a significant increase in precipitation strengthening,grain refinement strengthening and dislocation strengthening.

关 键 词：High-speed railway axle steel Nb microalloying PRECIPITATE Strengthening mechanism 

分 类 号：TG142[一般工业技术—材料科学与工程]