The mechanical properties and microstructure evolution of cold-deformed CrMnN austenitic stainless steel annealed in a temperature ranging from 50 ℃ to 650 ℃ for 90 min and at 550 ℃ for different time were investig...The mechanical properties and microstructure evolution of cold-deformed CrMnN austenitic stainless steel annealed in a temperature ranging from 50 ℃ to 650 ℃ for 90 min and at 550 ℃ for different time were investigated by tensile test, micro hardness test, and Transmission Electron Microscope （TEM）. The steel was strengthened when it got annealed at temperatures ranging from 100 ℃ to 550 ℃, while it was softened when it got annealed at temperatures ranging from 550 ℃ to 650 ℃. Annealing temperature had stronger effect on mechanical properties than annealing time. TEM observations showed that nano-sized precipitates formed when the steel was annealed at 150 ℃ for 90 min, but the size and density of precipitates had no noticeable change with annealing temperature and time. Recrystallization occurred when the steel was annealed at temperatures above 550 ℃ for 90 min, and its scale increased with annealing temperature. Nano-sized annealing twins were observed. The mechanisms that controlled the mechanical behaviors of the steel were discussed.展开更多
This paper gives a short introduction to the typical process route and material properties of these steels in comparison to standard martensitic corrosion-resistant steels. The typical response of these steels to vari...This paper gives a short introduction to the typical process route and material properties of these steels in comparison to standard martensitic corrosion-resistant steels. The typical response of these steels to various heat treatment parameters is shown and explained using the three grades M333, N360 and M340 (all made by Bohler Edelstahl GmbH) as examples, and the physical metallurgy of these steels and its consequences for practical heat treatment is explained. The correlation between tempering parameters and their effect on the toughness and corrosion properties is explained in particular detail, showing that these new steels not only offer far better property combinations under the usual heat treatment parameters than standard martensitic corrosion-resistant steels, but that they also open the door to extending heat treatment combinations and properties.展开更多
The grain size and precipitate amount which are affected by heat treatment have significant impact on the properties of high nitrogen austenitic stainless steel. In this study, Cr18Mn18 high nitrogen steel sheet is em...The grain size and precipitate amount which are affected by heat treatment have significant impact on the properties of high nitrogen austenitic stainless steel. In this study, Cr18Mn18 high nitrogen steel sheet is employed to investigate the effects of precipitate on austenitic grain size. It can be seen that the lamella precipitates which are rich in nitrogen and chromium nucleate in the austenite grain boundary and grow inward into grain when aged at 800 ℃ through electron probe micro-analyzer. The transmission electron microscopy results demonstrate that the precipitate is Cr2N and its morphology are detected as ellipsoid-like with major axis of 100-300 nm and minor axis of 50-100 nm roughly. The experiment show that coarsen of the austenite grain is quite critical at 1000-1100 ℃. However, the samples which pre-precipitated at 800 ℃ for 240 min to obtain the most nitride precipitate exhibits much smaller grain size than the as-rolled samples after solid solution treated at 1000, 1050 and 1100 ℃ for 240 min. The results show that the nitride precipitates in the grain boundary can effectively pin the austenite grain boundary and inhibit the grain growth.展开更多
基金Funded by of Liaoning Science and Technology Bureau(No.2007221007)
文摘The mechanical properties and microstructure evolution of cold-deformed CrMnN austenitic stainless steel annealed in a temperature ranging from 50 ℃ to 650 ℃ for 90 min and at 550 ℃ for different time were investigated by tensile test, micro hardness test, and Transmission Electron Microscope （TEM）. The steel was strengthened when it got annealed at temperatures ranging from 100 ℃ to 550 ℃, while it was softened when it got annealed at temperatures ranging from 550 ℃ to 650 ℃. Annealing temperature had stronger effect on mechanical properties than annealing time. TEM observations showed that nano-sized precipitates formed when the steel was annealed at 150 ℃ for 90 min, but the size and density of precipitates had no noticeable change with annealing temperature and time. Recrystallization occurred when the steel was annealed at temperatures above 550 ℃ for 90 min, and its scale increased with annealing temperature. Nano-sized annealing twins were observed. The mechanisms that controlled the mechanical behaviors of the steel were discussed.
文摘This paper gives a short introduction to the typical process route and material properties of these steels in comparison to standard martensitic corrosion-resistant steels. The typical response of these steels to various heat treatment parameters is shown and explained using the three grades M333, N360 and M340 (all made by Bohler Edelstahl GmbH) as examples, and the physical metallurgy of these steels and its consequences for practical heat treatment is explained. The correlation between tempering parameters and their effect on the toughness and corrosion properties is explained in particular detail, showing that these new steels not only offer far better property combinations under the usual heat treatment parameters than standard martensitic corrosion-resistant steels, but that they also open the door to extending heat treatment combinations and properties.
基金National Nature Science Foundation of China (50974014)
文摘The grain size and precipitate amount which are affected by heat treatment have significant impact on the properties of high nitrogen austenitic stainless steel. In this study, Cr18Mn18 high nitrogen steel sheet is employed to investigate the effects of precipitate on austenitic grain size. It can be seen that the lamella precipitates which are rich in nitrogen and chromium nucleate in the austenite grain boundary and grow inward into grain when aged at 800 ℃ through electron probe micro-analyzer. The transmission electron microscopy results demonstrate that the precipitate is Cr2N and its morphology are detected as ellipsoid-like with major axis of 100-300 nm and minor axis of 50-100 nm roughly. The experiment show that coarsen of the austenite grain is quite critical at 1000-1100 ℃. However, the samples which pre-precipitated at 800 ℃ for 240 min to obtain the most nitride precipitate exhibits much smaller grain size than the as-rolled samples after solid solution treated at 1000, 1050 and 1100 ℃ for 240 min. The results show that the nitride precipitates in the grain boundary can effectively pin the austenite grain boundary and inhibit the grain growth.
