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为了估算已产生裂纹汽缸的剩余寿命,本文对 ZG20CrMoV 钢在常温下进行疲劳裂纹扩展试验研究。根据汽轮机冷态和热态启动及负荷变化时的汽缸热应力值,在高频试验机上测得四组 a_i、N_i 值。疲劳裂纹扩展速率由裂纹扩展长度除以对应的循环次数来确定,而应力强度因子幅值ΔK_i 用平均裂纹长度计算。经回归后,得到裂纹扩展速率的基本公式。它们的相关系数在0.971～0.999范围内,证明这些方程是可靠的。同时测得该材料的门槛值为24.5kg/mm~(3/2)。
In order to estimate the residual life of a cracked cylinder, the fatigue crack propagation experiment of ZG20CrMoV steel at normal temperature was conducted in this paper. According to the turbine cold and hot start and load changes when the cylinder thermal stress value, measured in the high frequency test machine four groups a_i, N_i value. The fatigue crack growth rate is determined by dividing the crack propagation length by the corresponding number of cycles, while the stress intensity factor magnitude ΔK_i is calculated using the average crack length. After regression, the basic formula of crack propagation rate is obtained. Their correlation coefficients range from 0.971 to 0.999, proving that these equations are reliable. The threshold value of the material was measured at the same time as 24.5kg / mm ~ (3/2).