The precipitation kinetics of AlN and MnS in low carbon aluminium-killed steel was calculated.Transmission electron microscopy（TEM）,energy disperse spectroscopy（EDS） and phase analyses have been used to investigat...The precipitation kinetics of AlN and MnS in low carbon aluminium-killed steel was calculated.Transmission electron microscopy（TEM）,energy disperse spectroscopy（EDS） and phase analyses have been used to investigate the morphology,compositions and particle size distribution of AlN and MnS precipitates in three positions of the coil.The particles of AlN and MnS precipitates in the ferrite region after coiling and distributes along and adjacent to the ferrite grain boundaries.The shapes of AlN are plate-like,the precipitates size is about 10 to 60 nm;the shapes of MnS are spherical,the precipitates size is about 200 to 600 nm.The precipitation behavior of AlN is sensitive to the isothermal temperature and holding time,the precipitation quantity and particle size distribution of AlN in different positions of coil are unequal展开更多
The Al-9Zn-2.8Mg-2.5Cu-xZr-ySc alloys （x=0, 0.15%, 0.15%; y=0, 0.05%, 0.15%）, produced by low-frequent electromagnetic casting technology, were subjected to homogenization treatment, hot extrusion, solution and agin...The Al-9Zn-2.8Mg-2.5Cu-xZr-ySc alloys （x=0, 0.15%, 0.15%; y=0, 0.05%, 0.15%）, produced by low-frequent electromagnetic casting technology, were subjected to homogenization treatment, hot extrusion, solution and aging treatment. The effects of minor Sc and Zr addition on microstructure, recrystallization and properties of alloys were studied by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show that Sc and Zr addition can refine grains of the as-cast alloy by precipitation of primary Al3（Sc,Zr） particles formed during solidification as heterogeneous nuclei. Secondary Al3（Sc,Zr） precipitates formed during homogenization treatment strongly pin the movement of dislocation and subgrain boundaries, which can effectively inhibit the alloys recrystallization. Compared with the alloy without Sc and Zr addition, the Al-Zn-Mg-Cu-Zr alloy with 0.05%Sc and 0.15%Zr shows the increase in tensile strength and yield strength by 172 MPa and 218 MPa, respectively. Strengthening comes from the contributions of precipitation, substructure and grain refining.展开更多
The diurnal variation of precipitation over the Dabie Mountains(DBM) in eastern China during the 2013 mei-yu season is investigated with forecasts of a regional convection-permitting model. Simulated precipitation is ...The diurnal variation of precipitation over the Dabie Mountains(DBM) in eastern China during the 2013 mei-yu season is investigated with forecasts of a regional convection-permitting model. Simulated precipitation is verified against surface rain-gauge observations. The observed morning precipitation peak on the windward(relative to the prevailing synoptic-scale wind) side of the DBM is reproduced with good spatial and temporal accuracy. The interaction between the DBM and a nocturnal boundary layer low-level jet(BLJ) due to the inertial oscillation mechanism is shown to be responsible for this precipitation peak. The BLJ is aligned with the lower-level southwesterly synoptic-scale flow that carries abundant moisture.The BLJ core is established at around 0200 LST upwind of the mountains. It moves towards the DBM and reaches maximum intensity at about 70 km ahead of the mountains. When the BLJ impinges upon the windward side of the DBM in the early morning, mechanical lifting of moist air leads to condensation and subsequent precipitation.展开更多
South China （SC） experienced persistent heavy rain in June 2010. The climatic anomalies and related mechanism are analyzed in this study. Results show that the large-scale circulation pattern favorable for precipita...South China （SC） experienced persistent heavy rain in June 2010. The climatic anomalies and related mechanism are analyzed in this study. Results show that the large-scale circulation pattern favorable for precipitation was maintained. In the upper level, the South Asian High and westerly jet stream provided a divergent circulation over SC. In the middle and low levels, an anomalous strong subtropical high （STH） extended to the South China Sea. The southwesterly monsoon flow along the northwest flank of the STH transported abundant water vapor from the western North Pacific, the Bay of Bengal, and the South China Sea to SC. The precipitation can be classified into two types： the West Siberia low （WSL）-induced low-level cyclone mode, and the STH-induced low-level jet mode. STH and WSL indices are defined to estimate the influence of these two systems, respectively. Analysis shows that both are critical for precipitation, but their respective contributions differ from year to year. In 2010, both were important factors for the heavy rainfall in June.展开更多
To analyze a new heavy rain case over China during the year 2022, by using the data from NCC-CMA and NCEP, a heavy rain weather process in most areas of China from July 26 to 30, 2022 was analyzed. Synoptic methods we...To analyze a new heavy rain case over China during the year 2022, by using the data from NCC-CMA and NCEP, a heavy rain weather process in most areas of China from July 26 to 30, 2022 was analyzed. Synoptic methods were used in this research and results show that under the influence of low vortex and wind shear, the abundant water vapor supply brought by the southeast airflow in the lower level and the lifting of the Taihang Mountain, heavy rain weather occurred in the northern part of Henan, China. In the west of Liaoning and Jilin, the rainfall process had the characteristics of frontal rainfall and the stable precipitation resulted in heavy rain weather. To sum up, the rainfall process was mainly affected by the upper-level trough, low-level wind shear and low-level jet.展开更多
It is a common technical difficulty to improve the strength of low magnetic stainless steel plates on the premise of ensuring ductility,corrosion resistance,and low magnetism.In this paper,the chemical composition of ...It is a common technical difficulty to improve the strength of low magnetic stainless steel plates on the premise of ensuring ductility,corrosion resistance,and low magnetism.In this paper,the chemical composition of low magnetic stainless steels with excellent paramagnetic stabilities and corrosion resistances was formulated through composition design and calculation.Through the alloying of Nb,V,and N and the controlled hot rolling process,large numbers of uniformly distributed high-temperature second phase particles were formed in the steel plate,and low magnetic stainless steel 35 mm plate with yield strength,ultimate tensile strength and elongation of 407 MPa,739 MPa and 54%respectively were obtained.The main strengthening strategies of the steel were solid solution strengthening and precipitation strengthening.The precipitation law and types of the high-temperature second phase in the steel were explored.The micro structure of the steel plate was characterized by scanning electron microscope,electron probe microanalysis,and transmission electron microscope.The magnetic properties of the steel plate were tested by a vibrating sample magnetometer.The relative magnetic permeability of the hot rolled plate was 1.0063 which met the requirement of low magnetism.展开更多
基金Sponsored by National Research and Development Program in the 11th Five Year Plan of China(2006BAE03A06)
文摘The precipitation kinetics of AlN and MnS in low carbon aluminium-killed steel was calculated.Transmission electron microscopy（TEM）,energy disperse spectroscopy（EDS） and phase analyses have been used to investigate the morphology,compositions and particle size distribution of AlN and MnS precipitates in three positions of the coil.The particles of AlN and MnS precipitates in the ferrite region after coiling and distributes along and adjacent to the ferrite grain boundaries.The shapes of AlN are plate-like,the precipitates size is about 10 to 60 nm;the shapes of MnS are spherical,the precipitates size is about 200 to 600 nm.The precipitation behavior of AlN is sensitive to the isothermal temperature and holding time,the precipitation quantity and particle size distribution of AlN in different positions of coil are unequal
基金Project(0211002605132)supported by Institute of Multipurpose Utilization of Mineral Resources,Chinese Academy of Geological Sciences,ChinaProject(0211005303101)supported by the Fundamental Research Funds for the Central Universities,China+1 种基金Project(2010BB4074)supported by Natural Science Foundation Project of CQ CSTC,ChinaProject(2010ZD-02)supported by State Key Laboratory for Advanced Metals and Materials,China
文摘The Al-9Zn-2.8Mg-2.5Cu-xZr-ySc alloys （x=0, 0.15%, 0.15%; y=0, 0.05%, 0.15%）, produced by low-frequent electromagnetic casting technology, were subjected to homogenization treatment, hot extrusion, solution and aging treatment. The effects of minor Sc and Zr addition on microstructure, recrystallization and properties of alloys were studied by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show that Sc and Zr addition can refine grains of the as-cast alloy by precipitation of primary Al3（Sc,Zr） particles formed during solidification as heterogeneous nuclei. Secondary Al3（Sc,Zr） precipitates formed during homogenization treatment strongly pin the movement of dislocation and subgrain boundaries, which can effectively inhibit the alloys recrystallization. Compared with the alloy without Sc and Zr addition, the Al-Zn-Mg-Cu-Zr alloy with 0.05%Sc and 0.15%Zr shows the increase in tensile strength and yield strength by 172 MPa and 218 MPa, respectively. Strengthening comes from the contributions of precipitation, substructure and grain refining.
基金supported by the Special Foundation of the China Meteorological Administration (Grant No.GYHY201506006)supported by the National Science Foundation of China (Grant Nos.41405100,41322032 and 41275031)
文摘The diurnal variation of precipitation over the Dabie Mountains(DBM) in eastern China during the 2013 mei-yu season is investigated with forecasts of a regional convection-permitting model. Simulated precipitation is verified against surface rain-gauge observations. The observed morning precipitation peak on the windward(relative to the prevailing synoptic-scale wind) side of the DBM is reproduced with good spatial and temporal accuracy. The interaction between the DBM and a nocturnal boundary layer low-level jet(BLJ) due to the inertial oscillation mechanism is shown to be responsible for this precipitation peak. The BLJ is aligned with the lower-level southwesterly synoptic-scale flow that carries abundant moisture.The BLJ core is established at around 0200 LST upwind of the mountains. It moves towards the DBM and reaches maximum intensity at about 70 km ahead of the mountains. When the BLJ impinges upon the windward side of the DBM in the early morning, mechanical lifting of moist air leads to condensation and subsequent precipitation.
基金supported by the National Basic Research Program of China(Grant No.2009CB421405)the National Natural Science Foundation of China(Grant Nos.41025017and40921160379)partly supported by City University of Hong Kong(GrantNo.7002717)
文摘South China （SC） experienced persistent heavy rain in June 2010. The climatic anomalies and related mechanism are analyzed in this study. Results show that the large-scale circulation pattern favorable for precipitation was maintained. In the upper level, the South Asian High and westerly jet stream provided a divergent circulation over SC. In the middle and low levels, an anomalous strong subtropical high （STH） extended to the South China Sea. The southwesterly monsoon flow along the northwest flank of the STH transported abundant water vapor from the western North Pacific, the Bay of Bengal, and the South China Sea to SC. The precipitation can be classified into two types： the West Siberia low （WSL）-induced low-level cyclone mode, and the STH-induced low-level jet mode. STH and WSL indices are defined to estimate the influence of these two systems, respectively. Analysis shows that both are critical for precipitation, but their respective contributions differ from year to year. In 2010, both were important factors for the heavy rainfall in June.
文摘To analyze a new heavy rain case over China during the year 2022, by using the data from NCC-CMA and NCEP, a heavy rain weather process in most areas of China from July 26 to 30, 2022 was analyzed. Synoptic methods were used in this research and results show that under the influence of low vortex and wind shear, the abundant water vapor supply brought by the southeast airflow in the lower level and the lifting of the Taihang Mountain, heavy rain weather occurred in the northern part of Henan, China. In the west of Liaoning and Jilin, the rainfall process had the characteristics of frontal rainfall and the stable precipitation resulted in heavy rain weather. To sum up, the rainfall process was mainly affected by the upper-level trough, low-level wind shear and low-level jet.
基金supported by the National Key Research Project of China(2016YFB0300402)。
文摘It is a common technical difficulty to improve the strength of low magnetic stainless steel plates on the premise of ensuring ductility,corrosion resistance,and low magnetism.In this paper,the chemical composition of low magnetic stainless steels with excellent paramagnetic stabilities and corrosion resistances was formulated through composition design and calculation.Through the alloying of Nb,V,and N and the controlled hot rolling process,large numbers of uniformly distributed high-temperature second phase particles were formed in the steel plate,and low magnetic stainless steel 35 mm plate with yield strength,ultimate tensile strength and elongation of 407 MPa,739 MPa and 54%respectively were obtained.The main strengthening strategies of the steel were solid solution strengthening and precipitation strengthening.The precipitation law and types of the high-temperature second phase in the steel were explored.The micro structure of the steel plate was characterized by scanning electron microscope,electron probe microanalysis,and transmission electron microscope.The magnetic properties of the steel plate were tested by a vibrating sample magnetometer.The relative magnetic permeability of the hot rolled plate was 1.0063 which met the requirement of low magnetism.
