铁路货车车轴断裂分析

THE FRACTURE FAILURE ANALYSIS AT THE DOWNLOAD TROUGH OF THE WAGON AXLE

为查明铁路货车车轴卸荷槽部位断裂失效的原因,对断轴整体及断口部位做了全面的理化检验和宏、微观分析,发现轴表面疲劳源处存在许多腐蚀坑。进一步对腐蚀坑底部进行微观观察和电子能谱分析,发现坑底存在较多沿轴周向的微裂纹,坑内腐蚀产物含有高价硫元素。结果表明,较强腐蚀性物质使卸荷槽部位轴表面形成较深腐蚀坑,在该区域极易造成应力集中,这是引起裂纹萌生和扩展最终导致车轴断裂的主要原因。

In order to find out the reason of fatigue of the wagon axle on the download trough, physical-chemistry test and analysis were carried out on the whole axle and fracture surface, as a result, many corrosion pits were found on the fatigue source zone. By SEM, a lot of micro cracks developing on the direction of circle of axle cross section were found. The result of XPS shows that there is high sulphur element. So, the main reason of the micro cracks initiation and the failure of whole axle in the end is the concentrated strain caused by the deeper corrosion pits which were the results of some high corrosion medium eroding on the bottom of the download trough. And the micro-crack initiation and its extention were also described and discussed in this article.