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本文以40MnB、45Cr和42CrMo钢为材料,经淬火、500℃回火后,置于3.5%NaCl的盐水中,试验研究了疲劳裂纹内的腐蚀产物产生的条件和腐蚀产物降低疲劳裂纹扩展速率的机制。试验结果表明:1.使裂纹内连续地产生较多的腐蚀产物的条件之一是裂纹内的盐水中要含有一定量的氧,在疲劳裂纹扩展过程中,裂纹尖端的盐水中因电化学反应消耗掉的氧应得到连续地补充。2.腐蚀产物引起的腐蚀疲劳裂纹扩展速率的下降,不仅与腐蚀产物引起的“闭合效应”有关,也应与腐蚀产物堵塞了腐蚀介质(特别是氢)向裂纹尖端扩渗,使裂纹尖端一些局部地区成为瞬时真空有关。
In this paper, 40MnB, 45Cr and 42CrMo steel as the material, after quenching, tempering at 500 ℃, placed in 3.5% NaCl saline, the experimental study of the fatigue crack growth conditions and corrosion products to reduce the fatigue crack growth rate mechanism. The experimental results show that: 1. One of the conditions to make more corrosion products continuously in the crack is that the brine in the crack should contain a certain amount of oxygen. In the process of fatigue crack propagation, the salt solution in the tip of the crack is electrochemically reacted Oxygen consumption should be continually replenished. 2. Corrosion Fatigue Caused by Corrosion The decrease of the crack growth rate is not only related to the “closing effect” caused by the corrosion products, but also to the corrosive products which clog the corrosive medium (especially hydrogen) to the crack tip so as to make some crack tip Local area to instantaneous vacuum related.