The addition of high Ti（>0.1%） in microalloyed bainitic high strength steel was designed, and the precipitation morphology of steels with different Ti, Nb, and V contents was studied by utilizing transmission ele...The addition of high Ti（>0.1%） in microalloyed bainitic high strength steel was designed, and the precipitation morphology of steels with different Ti, Nb, and V contents was studied by utilizing transmission electron microscopy（TEM）. Based on the classical nucleation-crystal growth theory and the Johnson-Mehl-Avrami equation, the precipitation thermodynamic and kinetic model of second phase particles in austenite was established in the form of（Nbx,Vy,Tiz）C, and the complex precipitation mechanism of second phase particles was emphatically studied. The experimental results show that the complex precipitation particles could be divided into two categories: the coarser particles with about 100 nm grain size and the independent complex precipitation particles in the form of（Nb,V,Ti）C with 35-50 nm grain size. The latter has a better precipitation strengthening effect, and the calculated PTT curve shows a typical "C" shape. When the deformed storage energy is 3 820 J?mol-1, the fastest precipitation temperature of calculated PTT curve is 925 °C, and the calculated result is essentially consistent with experimental values. The increase of Ti content increased the nose point temperature and expanded the range of fastest precipitation temperature.展开更多
The static and dynamic precipitation behavior of solution-treated binary Al-20 wt.% Zn alloy is investigated via artificial aging, cold rolling and artificial aging combined with cold rolling. The solution-treated Al-...The static and dynamic precipitation behavior of solution-treated binary Al-20 wt.% Zn alloy is investigated via artificial aging, cold rolling and artificial aging combined with cold rolling. The solution-treated Al-Zn alloy exhibits high thermal stability during aging, and low densities of nano-sized Zn particles are precipitated along with AI grain boundaries after aging at 200℃ for 13 h. Compared with static precipitation, dynamic precipitation occurs more easily in the Al-Zn alloy. Zn clusters are obtained after cold rolling at an equivalent plastic strain of 0.6, and the size of the Zn phase reaches hundreds of nanometers when the strain is increased to 12.1. The results show that the speed of static precipitation can be significantly enhanced after the application of 2.9 rolling strain. Grain refinement and defects induced by cold rolling are considered to promote Zn precipitation. The hardness of Al-Zn alloy is also affected by static and dynamic precipitations.展开更多
基金Funded by the National Natural Science Foundation of China(No.U1860112)the State Key Laboratory of Marine Equipment made of Metal Material and Application(No.SKLMEAUSTL-201708 and No.SKLMEA-USTL-201703)+1 种基金the Key Project of Liaoning Education Department(No.2019FWDF03)the National Natural Science Foundation of USTL(No.2017QN11)
文摘The addition of high Ti（>0.1%） in microalloyed bainitic high strength steel was designed, and the precipitation morphology of steels with different Ti, Nb, and V contents was studied by utilizing transmission electron microscopy（TEM）. Based on the classical nucleation-crystal growth theory and the Johnson-Mehl-Avrami equation, the precipitation thermodynamic and kinetic model of second phase particles in austenite was established in the form of（Nbx,Vy,Tiz）C, and the complex precipitation mechanism of second phase particles was emphatically studied. The experimental results show that the complex precipitation particles could be divided into two categories: the coarser particles with about 100 nm grain size and the independent complex precipitation particles in the form of（Nb,V,Ti）C with 35-50 nm grain size. The latter has a better precipitation strengthening effect, and the calculated PTT curve shows a typical "C" shape. When the deformed storage energy is 3 820 J?mol-1, the fastest precipitation temperature of calculated PTT curve is 925 °C, and the calculated result is essentially consistent with experimental values. The increase of Ti content increased the nose point temperature and expanded the range of fastest precipitation temperature.
基金Supported by the National Basic Research Program of China under Grant No 2013CB733000the Natural Science Foundation of Guangxi Province under Grant No 2015GXNSFBA139238the Guangxi'Bagui'Teams for Innovation and Research
文摘The static and dynamic precipitation behavior of solution-treated binary Al-20 wt.% Zn alloy is investigated via artificial aging, cold rolling and artificial aging combined with cold rolling. The solution-treated Al-Zn alloy exhibits high thermal stability during aging, and low densities of nano-sized Zn particles are precipitated along with AI grain boundaries after aging at 200℃ for 13 h. Compared with static precipitation, dynamic precipitation occurs more easily in the Al-Zn alloy. Zn clusters are obtained after cold rolling at an equivalent plastic strain of 0.6, and the size of the Zn phase reaches hundreds of nanometers when the strain is increased to 12.1. The results show that the speed of static precipitation can be significantly enhanced after the application of 2.9 rolling strain. Grain refinement and defects induced by cold rolling are considered to promote Zn precipitation. The hardness of Al-Zn alloy is also affected by static and dynamic precipitations.
