钢轨弹条腐蚀疲劳断裂研究

Corrosion Fatigue Cracking Research of Rail Fastenings

钢轨固定用弹条使用两年左右后发生断裂,断裂弹条用于隧道内,环境比较潮湿。为弄清断裂原因,通过宏观观察、扫描电镜及能谱分析、金相检验等方法对断裂弹条进行了分析。结果表明:环境酸性较强,弹条锈蚀严重,锈蚀产物中探测到少量Cl、S元素;断裂起源于弹条对称内弧拉应力最大部位,断裂源锈蚀更为严重,局部形成尖锐缝隙,扩展区疲劳贝纹线明显,弹条断裂属腐蚀疲劳开裂。可通过使用抗腐蚀性能较强的材料,适当提高材料回火温度,表面热镀锌以及降低弹条使用年限等措施来预防。

The rail fastenings fractured when they were used in a humid tunnel about two years. Thefracture reasons were analysed with means of macroscopical observation,scanning electronic micro-scope and X ray energy spectrometer,metallography microscope and so on. The result shows thatenvironment is stronger acid and the fastenings are seriously rusty,a small quantity of Cl and S ele-ment is detected in the corrosion. The fracture origin lies in the symmetric inner arc where the tensilestress is ultimate and the narrow gap happened because of serious corrosion. The shell pattern is ap-parent,so the fastenings failure belongs to corrosion fatigue cracking. It can be prevented by usingbetter corrosion resistance steel,increasing tempering temperature properly,hot galvanizing and re-ducing the fastenings serviceable life.