泵轴断裂原因分析

通过大量的实验对失效后的减顶泵泵轴进行了详细分析与研究,确定了其失效的原因。对失效泵轴的化学成分、机械性能、金相组织以及蚀坑内的腐蚀产物等进行了检验,通过对检验结果的分析,确定泵轴失效的主要原因:一是组织中的非金属夹杂物严重超标;二是显微组织不符合技术要求;三是泵轴的键槽底部表面处发生了截面尺寸的突变,键槽根部为尖角并有蚀坑存在等。这些缺陷起着尖端缺口的作用,在交变的旋转弯曲载荷作用下,在这些缺陷处将产生严重的缺口效应,形成了很高的局部应力集中,从而导致了泵轴在缺陷处发生了疲劳断裂而失效。在明确了泵轴失效原因的基础上,提出了在生产中,预防泵轴过早发生疲劳断裂,延长其使用寿命所应采取的相应措施。

Fracture Analysis of Pump Axle

Through a great deal of experiments, a failure axle of air-breathing pump on the top of decompression tower was analyzed and researched in details, and then its causes of inactivation was found out. Chemical components, mechanical properties, metallurgical structure and corrosion substance in the pit of the pump axle were tested. By analyzing the results of tests, three main causes of the axle inactivation are concluded. Firstly, non-metallic inclusions in the microscopic structure go heavily beyond the standard value. Secondly, microscopic structure doesn't conform to technical requirements. Finally, in the bottom of pump axle's keyway, sectional dimension changes greatly, the keyway's root is sharp-angled, and there exist many corrosion pits. These defects act as sharp gaps. Under the effect of alternately rotating and winding load, notch effects happen heavily along these defects, and a very high local stress concentration is formed, which leads to failure due to pump axle's fatigue fracture. On the basis of confirming failure causes, a proposal is put forward that the relevant measures are taken to prevent pump axle from fatigue cracking too early and prolong its operating life.