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在623K的惰性气体和碘气氛中用反向弯曲的方法进行了Zr-2合金的低周疲劳试验。两种气氛中的疲劳均遵循Coffin-Manson定律。裂纹扩展按穿晶剪切模式,在惰性气氛中裂纹扩展是疲劳寿命的控制因素。在高浓度碘蒸汽中的疲劳寿命与在惰性气氛中寿命相比要短得多,碘蒸汽主要以穿晶解理方式引起样品的脆性断裂,并加快裂纹扩展速度。在疲劳条件下引起脆性断裂的最低碘蒸汽压力是27帕左右。
The low cycle fatigue test of Zr-2 alloy was carried out by reverse bending in a 623K inert gas and iodine atmosphere. Fatigue in both atmospheres follows Coffin-Manson’s law. Crack propagation is based on the transgranular shear mode, where crack propagation is the controlling factor of fatigue life in an inert atmosphere. The fatigue life in high-concentration iodine steam is much shorter than that in inert atmosphere, and the iodine vapor mainly causes the brittle fracture of the sample by means of transgranular cleavage and accelerates the crack propagation speed. The lowest iodine vapor pressure that causes brittle fracture under fatigue conditions is about 27 Pa.