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一、前言ZG—18铸钢是一种不含镍的高强度铸造结构钢,用来制造飞机上的某些受力结构件。在研制过程中,发现在等强度条件下,铸钢的疲劳极限(?)低于同类锻钢,而疲劳裂纹扩展寿命优于锻钢,成为安全寿命设计需要考虑的一个重要问题。为此,我们对铸钢与锻钢的疲劳裂纹的形成寿命与扩展寿命进行了一些对比试验研究,并作了初步分析讨论。疲劳裂纹的总寿命 N_f,一般均包括裂纹的形成寿命 N_o 与扩展寿命 N_p。即:
I. Introduction ZG-18 cast steel is a nickel-free cast high-strength structural steel used to make some of the force structure on the aircraft. During the process of development, it was found that under the condition of equal strength, the fatigue limit (?) Of cast steel is lower than that of forged steel and the fatigue crack propagation life is better than that of forged steel, which becomes an important issue to be considered in safety life design. For this reason, we made a comparative study on the forming fatigue life and extended life of cast steel and forged steel, and made a preliminary analysis and discussion. The fatigue life of the total fatigue life N_f, generally include the formation of crack life N_o and extended life N_p. which is: