Effect of cerium(Ce)on creep strength and microstructure of 316LN austenitic stainless steel(316LN steel)at 700℃/150 MPa was investigated by scanning electron microscopy(SEM),scanning transmission electron microscopy...Effect of cerium(Ce)on creep strength and microstructure of 316LN austenitic stainless steel(316LN steel)at 700℃/150 MPa was investigated by scanning electron microscopy(SEM),scanning transmission electron microscopy(STEM)and thermodynamic calculations.Addition of 0.032 wt%Ce to 316LN steel results in a prominent increase in creep life from 313 to 556 h.Ce enriches in titanium nitride nanoparticles,increases slightly the activity and diffusion coefficient of Mo,and facilitates the formation of fine and dense intragranular Laves phase precipitates.Thus the creep strength is remarkably enhanced by Ce addition in 316LN steel through the intragranular Laves phase precipitation strengthening.It reveals a new insight into the improvement effect of rare earth(RE)elements such as Ce on creep strength of austenitic stainless steels,which inspired the design of RE-microalloying heat-resistant steels.展开更多
The redistribution of C and N atoms during cryogenic treatment is crucial for the microstructure evolution and properties of high nitrogen martensitic steel.Here,the distinct redistribution behavior of C and N atoms i...The redistribution of C and N atoms during cryogenic treatment is crucial for the microstructure evolution and properties of high nitrogen martensitic steel.Here,the distinct redistribution behavior of C and N atoms in a martensitic stainless steel with 0.3 wt%C and 0.5 wt%N after cryogenic treatment were investigated by the atom probe tomography.Carbon clusters begin to form after cryogenic treatment at-60℃and gradually increase with the decrease of cryogenic treatment temperature.While Mo–N and Cr–N pairs are homogeneously distributed in the matrix even after cryogenic treatment at-120℃,and then form enrichment phenomenon when the cryogenic temperature is deeply lowered to-190℃.It is found that the distinct redistributions of C and N atoms are associated with the different interaction energy between substitutional atoms and them.The stronger interaction between Cr,Mo atoms and N delays the segregation of N during the cryogenic treatment.Finally,the mechanical properties results confirmed that the deep lower cryogenic treatment is a promising method to improve the hardness and strength in the high nitrogen martensitic stainless steel.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51871212)the National Key Research and Development Program of China(2020YFB2006800)+4 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDC04010400)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y2021060)the Key Project for the Application of Advances in Science and Technology of the Chinese Academy of Sciences(KFJ-HGZX-032)the Project for the Application of Advances in Science and Technology of the Chinese Academy of Sciences in Henan Province(2022203)the K.C.Wong Education Foundation。
文摘Effect of cerium(Ce)on creep strength and microstructure of 316LN austenitic stainless steel(316LN steel)at 700℃/150 MPa was investigated by scanning electron microscopy(SEM),scanning transmission electron microscopy(STEM)and thermodynamic calculations.Addition of 0.032 wt%Ce to 316LN steel results in a prominent increase in creep life from 313 to 556 h.Ce enriches in titanium nitride nanoparticles,increases slightly the activity and diffusion coefficient of Mo,and facilitates the formation of fine and dense intragranular Laves phase precipitates.Thus the creep strength is remarkably enhanced by Ce addition in 316LN steel through the intragranular Laves phase precipitation strengthening.It reveals a new insight into the improvement effect of rare earth(RE)elements such as Ce on creep strength of austenitic stainless steels,which inspired the design of RE-microalloying heat-resistant steels.
基金supported by the National Natural Science Foundation of China(No.51871212)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDC04000000)+1 种基金the Major Scientific and Technological Projects of Jiangxi Province(No.20194ABC28011)the Project to Strengthen Industrial Development at the Grass-roots Level(TC190A4DA/35)。
文摘The redistribution of C and N atoms during cryogenic treatment is crucial for the microstructure evolution and properties of high nitrogen martensitic steel.Here,the distinct redistribution behavior of C and N atoms in a martensitic stainless steel with 0.3 wt%C and 0.5 wt%N after cryogenic treatment were investigated by the atom probe tomography.Carbon clusters begin to form after cryogenic treatment at-60℃and gradually increase with the decrease of cryogenic treatment temperature.While Mo–N and Cr–N pairs are homogeneously distributed in the matrix even after cryogenic treatment at-120℃,and then form enrichment phenomenon when the cryogenic temperature is deeply lowered to-190℃.It is found that the distinct redistributions of C and N atoms are associated with the different interaction energy between substitutional atoms and them.The stronger interaction between Cr,Mo atoms and N delays the segregation of N during the cryogenic treatment.Finally,the mechanical properties results confirmed that the deep lower cryogenic treatment is a promising method to improve the hardness and strength in the high nitrogen martensitic stainless steel.
