Due to the rapid development of China＇ s rail transportation equipment manufacturing industry and related international distribution, important material suppliers such as Baoshan Iron ＆ Steel Co., Ltd. carries on in...Due to the rapid development of China＇ s rail transportation equipment manufacturing industry and related international distribution, important material suppliers such as Baoshan Iron ＆ Steel Co., Ltd. carries on investigating the stability of material under extremely cold conditions. In this study, mechanical properties and secondary work embrittlement of weathering steel 05CuPCrNi were tested at low temperature. Compared to the mechanical properties at room temperature, the yield and tensile strength increase slightly with decreasing temperature. However, the variation of elongation is not obvious. The experimental results also show that the secondary work embrittlement transition temperature of 05CuPCrNi is lower than - 60 ℃. These results provide the basis for the use of this train body material in extremely cold regions.展开更多
The hardness and microstructure evolution of a 8% Cr cold work tool steel during tempering for 40 h were investigated. Transmission electron microscope examinations showed that M_3C carbides precipitated from supersat...The hardness and microstructure evolution of a 8% Cr cold work tool steel during tempering for 40 h were investigated. Transmission electron microscope examinations showed that M_3C carbides precipitated from supersaturated martensite after tempering at 350 ℃. When the tempering temperature was higher than 520 ℃,the M_（23）C_6 carbides precipitated to substitute for M_3C carbides. After ageing at the temperature of 520 ℃ for 40 h,it was observed that very fine and dense secondary Mo_2C precipitates were precipitated. Thus,it can be concluded that the early stage of Mo_2C-carbide precipitation is like to be Gunier-Preston（ G-P） zone formed by [Mo-C] segregation group which is responsible for the secondary hardening peak at 520 ℃. Overageing at 700 ℃ resulted in recovery of martensitic microstructure and precipitation of M_（23）C_6 carbides.When ageing at 700 ℃ for more than 20 h,recrystallization occurred,which resulted in a change of the matrix morphology from martensitic plates to equiaxed ferrite. It was noticed that the size of recrystallized grain / subgrain was very fine,which was attributed to the pinning effect of M_（23）C_6 precipitates.展开更多
文摘Due to the rapid development of China＇ s rail transportation equipment manufacturing industry and related international distribution, important material suppliers such as Baoshan Iron ＆ Steel Co., Ltd. carries on investigating the stability of material under extremely cold conditions. In this study, mechanical properties and secondary work embrittlement of weathering steel 05CuPCrNi were tested at low temperature. Compared to the mechanical properties at room temperature, the yield and tensile strength increase slightly with decreasing temperature. However, the variation of elongation is not obvious. The experimental results also show that the secondary work embrittlement transition temperature of 05CuPCrNi is lower than - 60 ℃. These results provide the basis for the use of this train body material in extremely cold regions.
基金Item Sponsored by National Key Technologies Research and Development Program of China(2007BAE510B04)
文摘The hardness and microstructure evolution of a 8% Cr cold work tool steel during tempering for 40 h were investigated. Transmission electron microscope examinations showed that M_3C carbides precipitated from supersaturated martensite after tempering at 350 ℃. When the tempering temperature was higher than 520 ℃,the M_（23）C_6 carbides precipitated to substitute for M_3C carbides. After ageing at the temperature of 520 ℃ for 40 h,it was observed that very fine and dense secondary Mo_2C precipitates were precipitated. Thus,it can be concluded that the early stage of Mo_2C-carbide precipitation is like to be Gunier-Preston（ G-P） zone formed by [Mo-C] segregation group which is responsible for the secondary hardening peak at 520 ℃. Overageing at 700 ℃ resulted in recovery of martensitic microstructure and precipitation of M_（23）C_6 carbides.When ageing at 700 ℃ for more than 20 h,recrystallization occurred,which resulted in a change of the matrix morphology from martensitic plates to equiaxed ferrite. It was noticed that the size of recrystallized grain / subgrain was very fine,which was attributed to the pinning effect of M_（23）C_6 precipitates.
