模拟火灾作用对紫铜焊接接头组织和性能的影响

Effect of simulated fire on microstructures and properties of copper welded joint

为了得到实际火灾现场中火焰和辐射热对电线及连接部位的电气损伤,模拟了不同温度对4 mm厚的T3紫铜板焊接接头的作用,通过对焊接接头力学性能、电学性能和显微组织的分析,并将金属结晶及热处理理论与火灾作用机理相比拟,得出温度对紫铜焊接接头组织和性能的影响规律.结果表明,当火灾温度较低时,硬度会因退火强化而略有升高,不会造成影响;当温度高于650℃时,硬度明显降低,火灾温度会对其造成严重性破坏;电阻率随温度变化影响不大;焊缝组织为粗大的α-Cu晶粒,内部有胞状晶亚结构生成,随温度升高,晶粒长大,亚结构数量逐渐减少且分布弥散.

In order to obtain the effect and electrical injury of the flames and radiant heat on the wires and connecting parts in actual fire scene,a T3 copper plate 4 mm thick was welded by TIG at different temperatures.Through the mechanical and electronic properties and microstructure analysis of welded joints and a comparison of the crystallization and heat treatment theory of metal with fire mechanism,the effects of temperature on the microstructures and properties of copper welded joints were investigated.The results show that the hardness will be slightly higher due to enhanced annealing when the fire temperature is low,which does not affect by fire.But when the temperature is above 650 ℃,the hardness significantly declines,which causes the seriousness damage;electrical resistivity has little changes.The microstructures of welded joint is coarse grains of α-Cu and crystal within the celluliform metastructure generated.With increasing temperature,the grain growth and the number of sub-structure decrease and diffuse.