Through the thermo-mechanical control process （TMCP）, a high Nb low Mo fire resistant steel with the yield strength （YS） of 521 MPa at room temperature （RT） and 360 MPa at elevated temperature （ET） of 600 ℃ w...Through the thermo-mechanical control process （TMCP）, a high Nb low Mo fire resistant steel with the yield strength （YS） of 521 MPa at room temperature （RT） and 360 MPa at elevated temperature （ET） of 600 ℃ was developed based on MX （M=Nb, V, Mo; X=C,N） precipitation strengthening. A series of tensile and con- stant load tests were conducted to study the mechanical properties at ET. The dynamic continuous cooling transfor- mation （CCT） as well as precipitation behavior of microalloy carbonitride was investigated by means of thermal sim- ulator and electron microscopy approaches. Results showed that the failure temperature of tested steel was deter- mined as 653 ℃, and the granular bainite was obtained when the cooling rate was higher than 10 ℃/s. In the rolled state, a certain amount of M/A islands was observed. During heating from RT to ET, M/A islands disappeared, and cementites and high dense compound precipitates （Nb, Mo, V）C with size of less than 10 nm precipitated in ferrite at ET （600 ℃）, which resulted in precipitation strengthening at ET.展开更多
Fire disaster is the primary one of the facts of deforestation. Although in recent years the level of forest management and technique for fire suppression have been improving and fire fighting force has been strengthe...Fire disaster is the primary one of the facts of deforestation. Although in recent years the level of forest management and technique for fire suppression have been improving and fire fighting force has been strengthened, the area of fire has not been decreased obviously. Using biological fire resistant technique can effectively prevent the campaign fire. In this paper, fire resistant ability and component about 12 tree species, in mountain area of Daguishan, Guangxi Zhuang Autonomous Region, have been ...展开更多
Selection of fire resistant tree species for the southwestern China and the planting of those species can effectively prevent large area's fire damage. In this paper the components and flammability of leaves, twi...Selection of fire resistant tree species for the southwestern China and the planting of those species can effectively prevent large area's fire damage. In this paper the components and flammability of leaves, twigs and barks of 12 tree species in the mountain area of southwestern China have been tested and analyzed in the laboratory. The test and analysis indicate the results as follows:(1) for all the tree species, the fire resistance of leaves is much weaker than that of twigs and barks, and the broad leaves are stronger than those of conifers in fire resistance. (2) Heat value, moisture, ignition point and ash content are main indexes to affect fire resistance. Heat value relates to lignose content and benzene ethanol extractive content linearly.(3) Of all the 12 tree species, Schima superba,Castanopsis hystrix, Myrica rubra have the strongest resistance to fire; Machilus pauhoi, Michelia macclurei, Mytilaria laosensis, Camellia olifera and Manglietia tenuipes are relatively strong in fire resistance, and Lithocapus thalassica, Tsoongiodendron odorum, Cunninghamia lanceolata and Pinus massoniana are weak in fire resistance.展开更多
基金Item Sponsored by National Basic Research Program of China(2010CB630805)
文摘Through the thermo-mechanical control process （TMCP）, a high Nb low Mo fire resistant steel with the yield strength （YS） of 521 MPa at room temperature （RT） and 360 MPa at elevated temperature （ET） of 600 ℃ was developed based on MX （M=Nb, V, Mo; X=C,N） precipitation strengthening. A series of tensile and con- stant load tests were conducted to study the mechanical properties at ET. The dynamic continuous cooling transfor- mation （CCT） as well as precipitation behavior of microalloy carbonitride was investigated by means of thermal sim- ulator and electron microscopy approaches. Results showed that the failure temperature of tested steel was deter- mined as 653 ℃, and the granular bainite was obtained when the cooling rate was higher than 10 ℃/s. In the rolled state, a certain amount of M/A islands was observed. During heating from RT to ET, M/A islands disappeared, and cementites and high dense compound precipitates （Nb, Mo, V）C with size of less than 10 nm precipitated in ferrite at ET （600 ℃）, which resulted in precipitation strengthening at ET.
基金the major project of forestry(No.2000-14)the National Natural Science of Beijing(No.6992025)
文摘Fire disaster is the primary one of the facts of deforestation. Although in recent years the level of forest management and technique for fire suppression have been improving and fire fighting force has been strengthened, the area of fire has not been decreased obviously. Using biological fire resistant technique can effectively prevent the campaign fire. In this paper, fire resistant ability and component about 12 tree species, in mountain area of Daguishan, Guangxi Zhuang Autonomous Region, have been ...
文摘Selection of fire resistant tree species for the southwestern China and the planting of those species can effectively prevent large area's fire damage. In this paper the components and flammability of leaves, twigs and barks of 12 tree species in the mountain area of southwestern China have been tested and analyzed in the laboratory. The test and analysis indicate the results as follows:(1) for all the tree species, the fire resistance of leaves is much weaker than that of twigs and barks, and the broad leaves are stronger than those of conifers in fire resistance. (2) Heat value, moisture, ignition point and ash content are main indexes to affect fire resistance. Heat value relates to lignose content and benzene ethanol extractive content linearly.(3) Of all the 12 tree species, Schima superba,Castanopsis hystrix, Myrica rubra have the strongest resistance to fire; Machilus pauhoi, Michelia macclurei, Mytilaria laosensis, Camellia olifera and Manglietia tenuipes are relatively strong in fire resistance, and Lithocapus thalassica, Tsoongiodendron odorum, Cunninghamia lanceolata and Pinus massoniana are weak in fire resistance.
