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本文对4330M钢在蒸馏水中的腐蚀疲劳裂纹扩展速率进行了定量研究。测出4330M钢在蒸馏水中的(da/dt)-K曲线,并在R=0.2,0.6,0.7,0.8四种情况下测出4330M钢在氩气中和在蒸馏水中的(da/dN)-△K曲线。研究了应力比R对腐蚀疲劳的影响。 在上述实验基础上,拟制了一个BASIC计算程序,根据应力腐蚀和氩气气氛下疲劳的实验数据,用电子计算机对叠加模型和竞争模型分别算出以每周表示的应力腐蚀裂纹扩展速率(da/dN)_(SCC)。比较了两种模型的相互关系。计算结果表明4330M钢在蒸馏水中的腐蚀疲劳实验数据和Austen提出的竞争模型相符合。本文对竞争模型进行修正,提出要加上考虑交互作用的修正项。使用经修正后的竞争模型,就能解释腐蚀疲劳裂纹扩展速率定量研究方面存在的一些问题。 试验结果表明,4330M钢适用于研究腐蚀疲劳裂纹扩展的机制问题。

The behaviour of corrosion fatigue crack propagation in 4330M steel in distilled water has been investigated. The rate of stress corrosion crack propagation in distlled water, the fatigue crack propagation in argon and the corrosion fatigue crack propagation in distilled water with stress ratio R=0.2, 0.6, 0.7 and 0.8 were measured. The rate of stress corrosion crack growth per second da/dt and the rate of fatigue crack growth per cycle da/dN are related to the crack tip stress intensity factor K and cycle range of stress intensity ΔK respectively.A BASIC computer program has been developed to calculate the cyclic rate of stress corrosion crack propagation (da/dN)_(SCC) with the experimental data of the time rate da/dt. The cyclic rate of corrosion fatigue crack propagation (da/dN)_(CF) based on both the "linear summation model" and the "process competition model" were also calculated by computer respectively and compared with the experimental data. It is shown that the experimental results consist the "process competition model" suggested by I. M. Austen. However, a modification to the "process competition model" was represented in which an interaction term is added.The basis of this modified "process competition model" is that: the fatigue and the stress corrosion crack growth process including their interaction terms are mutually competitive and that the crack will propagate at the fastest. Thus, the cyclic rate of stress corrosion fatigue crack growth (da/dN)_(CF) is (da/dN)_(CF)=(da/dN)_F+(da/dN)_(int F) or (da/dN)_(CF)= (da/dN)_(SCC)+ (da/dN)_(int S) where (da/dN)_F and (da/dN)_(SCC) are the cyclic rate of fatigue crack growth and of stress corrosion crack growth respectively, and (da/dN)_(int F) and (da/dN)_(int S) are the additional value of da/dN due to the interaction between the environment (water) and fatigue on (da/dN)_F and (da/dN)_(SCC) respectively.Some discrepancies of experimental results in quantitative understanding of corrosion crack growth rate were explained and treated uniquely this model.The results presented here shows that the steel used in this paper is appropriate for systematic study of mechanisms of stress corrosion fatigue crack propagation.