温度对N18(NZ2)合金循环变形行为的影响

研究了200、300、400℃温度下N18(NZ2)合金的循环变形行为,同时研究了室温和400℃低周疲劳行为.结果表明:N18(NZ2)合金低周疲劳寿命Nf随着塑性应变范围△εp的增加而降低,并遵循Coffin-Manson关系:Nβf△εp=C;N18(NZ2)合金在400℃高温下,其循环滞后回线出现锯齿状波形,即出现Portevin-LeChatelier效应.且在200、300、400 ℃下,合金表现出与常温下不同的循环特性,呈现出一致循环硬化的现象;在高温,N18(NZ2)合金疲劳断口局部出现韧窝型断裂,并出现细小的二次裂纹.大量二次裂纹的存在是400℃疲劳断口的主要特征.

Effect of Temperature on Cyclic Deformation Behavior of Zr-Sn-Nb Alloy

Effect of temperature on the cyclic deformation behaviors of Zr-Sn-Nb alloy(N18 alloy)at temperatures of 200,300.400℃and the low cycle fatigue(LCF)behaviors at room temperature(RT)and 400℃have been investigated.The results indicate that LCF lifetime of N18 alloy decreases with increasing of the plastic strain range Aεp and obeys Coffin-Manson relation:Nβf△εp=C;At 400℃,there exist sawtooth shaped hysteresis loops,Such phenomenon belongs to"PortevinLeChatelier effect"(PLC effect).At 200,300 and 400℃,there are different cyclic characteristics.At elevated temperature,the fatigue fracture is characterized by dimples and secondary cracks,while mainly by secondary cracks at 400℃.