电气火灾中铝导线短路熔珠凝固后高温火烧对金相组织的影响

Electrical Fire Chinalco Short-circuit Bead Wire High Temperature Fire's Influence on the Microstructure after Solidification

研究气体火灾中铝导线短路熔珠凝固后高温火烧对金相组织的影响。选用航空导线FVL与民用导线BV作为实验材料,对铝导线短路熔珠进行制备,对电气火灾中铝导线短路熔珠凝固后的温度进行模拟。结果:在高温、中温、低温环境下熔珠中共晶体含量大致一样,不同温度状态下均有部分熔珠内无共晶体存在,温度越低,无共晶体析出的熔珠数量越多。将凝固后的铝导线短路熔珠在1 000℃环境下加热10 min后,其金相组织主要是纤细的晶体状,熔珠中有部分细小等轴晶,有气孔现象出现;加热25 min和40 min后,其金相组织显示晶体已经变成粗大柱状晶体,其中含有少量气孔;加热55 min和70 min后,金相组织为粗大柱状晶和粗大等轴晶并存,晶界很明显,没有气孔现象。将凝固后的铝导线短路熔珠在500℃环境下加热20 min后的金相组织主要为等轴晶,其直径较小,分布均匀,晶界显著,有部分气孔存在;在800℃环境下加热20 min后的金相组织以等轴晶为主,晶粒直径不大同时较为均匀,晶界显著,形状相似;在1 000℃环境下加热20 min后的金相组织主要是等轴晶,晶粒直径较大,晶界显著,分布均匀,晶粒明显大于500℃和800℃的加热环境。高温环境下的铝导线短路熔珠密度明显高于中温和低温环境。结论:电气火灾中铝导线短路熔珠凝固后高温火烧能够使金相组织中晶粒变大,令熔珠中的气孔消失。

To study the gas fire chinalco short-circuit bead wire high temperature fire＆#39;s influence on the microstructure after solidification.BV FVL and civil aviation wires wires were choosen as experimental material, the preparation of aluminum conductor short-circuit bead, for electrical fire chinalco short-circuit bead wire after solidification temperature were simulated.Under the environment of high temperature, medium temperature, low temperature bead of the communist party of China crystal content is roughly same, in different temperature conditions are part of the bead is no eutectic, the lower the temperature, no crystal bead the more precipitation.After solidification of aluminum conductor short-circuit bead when heated to 1 000 ℃ environment after 10 min, its microstructure is fine crystalline, some small equiaxial crystal bead, stomatal phenomenon;heating after 25 min and 40 min, the microstructure showed that the crystal has become bulky columnar crystals, which contains a small amount of porosity;After heated 55 min and 70 min, microstructure for bulky columnar crystal and bulky isometric coexist, grain boundary obviously, no stomatal phenomenon.After solidification of aluminum conductor short-circuit bead when heated to 500 ℃ environment after 20 min of microstructure is mainly for the isometric, its diameter is small, uniform distribution, grain boundary, there is a part of the porosity;when heated to 800 ℃ environment after 20 min of microstructure is given priority to with isometric, grain diameter is relatively homogeneous at the same time, the grain boundary, the shape is similar;when heated to 1 000 ℃ environment after 20 min of microstructure is mainly the equiaxial crystal, and the diameter of grain, grain boundary, uniform distribution, grain significantly greater than 500 ℃ and 800 ℃ heating environment.Under the environment of high temperature aluminum conductor short-circuit bead density were significantly higher than those in the moderate low temperature environment.Electrical fire chinalco short-circuit bead wire high temperature burning can make grain size in the microstructure after solidification, the bead of the porosity.