The quench sensitivity of 6351 alloy was determined by the time temperature-transformation（TTT） curves and time temperature-property（TTP） curves by an interrupted quench technique with measurement of as-aged hardn...The quench sensitivity of 6351 alloy was determined by the time temperature-transformation（TTT） curves and time temperature-property（TTP） curves by an interrupted quench technique with measurement of as-aged hardness and as-quenched electro-conductivity.The microstructure transformation during isothermal treatment was studied by the transmission electron microscopy（TEM） and Avrami equation.The results showed that the electro-conductivity of the 6351 alloy increased and the hardness decreased with prolonging the holding time at a certain isothermal temperature.The TEM observation indicated that the supersaturated solid solution decomposed and needles β″ precipitated at the initial stage of isothermal holding.With the prolongation of holding time at the nose temperature,rod β＇ and plate β phases formed.The isothermal transformation rate at 360℃ was the fastest,and became slow at 280℃ and reached the slowest at 440℃.The nose temperatures of the TTT and TTP curves were about 360℃ and the high quench sensitive temperature range was 230 430℃.The quench factor analysis indicated that the cooling rate should be more than 15℃/s in the quench sensitive areas in order to get optimal mechanical properties.展开更多
There are many kinds of fires occurring under different conditions. For a specific site, it is difficult to collect sufficient data for analyzing the fire risk. In this paper, we suggest an information diffusion techn...There are many kinds of fires occurring under different conditions. For a specific site, it is difficult to collect sufficient data for analyzing the fire risk. In this paper, we suggest an information diffusion technique to analyze fire risk with a small sample. The information distribution method is applied to change crisp observations into fuzzy sets, and then to effectively construct a fuzzy relationship between fire and surroundings. With the data of Shanghai in winter, we show how to use the technique to analyze the fire risk.展开更多
Based on reason analyses for frequent flameout of HG-1025/18.2-YM6 boiler in a given power plant after coal quality variation, major factors such as unreasonable burner structure and inappropriate secondary air distri...Based on reason analyses for frequent flameout of HG-1025/18.2-YM6 boiler in a given power plant after coal quality variation, major factors such as unreasonable burner structure and inappropriate secondary air distribution were discussed in detail. A new mode of secondary air distribution was introduced to optimize the combustion performance, and a lower burner was retrofitted by increasing the relative distance between the primary air fuel rich-lean nozzles and reducing the size of waist air nozzles as well. As a result, the recirculating zone became more stable and the burner's combustion stability was improved.Practical operation shows that the modifications are so effective that the flameout problems caused by instable combustion never occur in operation.展开更多
基金Project(2012M511552) supported by China Postdoctoral Science FoundationProject(2009A080205001) supported by the State Key Fundamental Research Program of China
文摘The quench sensitivity of 6351 alloy was determined by the time temperature-transformation（TTT） curves and time temperature-property（TTP） curves by an interrupted quench technique with measurement of as-aged hardness and as-quenched electro-conductivity.The microstructure transformation during isothermal treatment was studied by the transmission electron microscopy（TEM） and Avrami equation.The results showed that the electro-conductivity of the 6351 alloy increased and the hardness decreased with prolonging the holding time at a certain isothermal temperature.The TEM observation indicated that the supersaturated solid solution decomposed and needles β″ precipitated at the initial stage of isothermal holding.With the prolongation of holding time at the nose temperature,rod β＇ and plate β phases formed.The isothermal transformation rate at 360℃ was the fastest,and became slow at 280℃ and reached the slowest at 440℃.The nose temperatures of the TTT and TTP curves were about 360℃ and the high quench sensitive temperature range was 230 430℃.The quench factor analysis indicated that the cooling rate should be more than 15℃/s in the quench sensitive areas in order to get optimal mechanical properties.
文摘There are many kinds of fires occurring under different conditions. For a specific site, it is difficult to collect sufficient data for analyzing the fire risk. In this paper, we suggest an information diffusion technique to analyze fire risk with a small sample. The information distribution method is applied to change crisp observations into fuzzy sets, and then to effectively construct a fuzzy relationship between fire and surroundings. With the data of Shanghai in winter, we show how to use the technique to analyze the fire risk.
文摘Based on reason analyses for frequent flameout of HG-1025/18.2-YM6 boiler in a given power plant after coal quality variation, major factors such as unreasonable burner structure and inappropriate secondary air distribution were discussed in detail. A new mode of secondary air distribution was introduced to optimize the combustion performance, and a lower burner was retrofitted by increasing the relative distance between the primary air fuel rich-lean nozzles and reducing the size of waist air nozzles as well. As a result, the recirculating zone became more stable and the burner's combustion stability was improved.Practical operation shows that the modifications are so effective that the flameout problems caused by instable combustion never occur in operation.
