摘要
为了研究Cu-Mg合金承力索在隧道内产生裂纹的原因和分析承力索失效机理,利用拉力试验机分别对未经施挂和施挂三个月后的承力索进行力学测试,对比分析施挂后承力索力学性能的变化,结合对失效承力索进行组织侵蚀和未经组织侵蚀的纵截面金相形貌观察,进而分析单丝裂纹断口形式,判断承力索失效特征。基于SEM形貌、能谱分析和EBSD检测,对承力索裂纹断口处的显微组织进行对比观察和分析,探讨承力索失效原因和机理。通过综合分析表明,Cu-Mg合金承力索线材存在明显的应力腐蚀开裂特征,并且考虑到承力索线材自身受到水泥污染、承力索悬挂张力和环境气氛的影响,而这些都是使承力索产生应力腐蚀开裂的重要因素。另外,Cu-Mg合金承力索单丝线材冷加工变形量大,加工硬化程度较高,参与应力大,失效样品裂纹处晶粒较小,晶界占比较大,对应力腐蚀裂纹的扩展有正向推动效应。
In order to study the causes of cracks in the Cu-Mg alloy catenary in the tunnel and analyze the failure mechanism of the catenary,the tensile testing machine was used to perform mechanical tests on the catenary unattached and the catenary after three months of suspension,comparative analysis of the change of mechanical properties of the wire after suspension,was combined with the metallographic morphology of the longitudinal section of the failed single wire with and without tissue erosion,and then the fracture form of the single wire crack was analyzed to judge the failure characteristics of the catenary.Based on SEM morphology,energy spectrum analysis and EBSD detection,the microstructure at the cracked fracture of the catenary was observed and analyzed,and the failure reason and mechanism of the catenary were discussed.Comprehensive analysis shows that the Cu-Mg alloy catenary has the characteristics of stress corrosion sensitivity,and taking into account the cement contamination of the bearing cable itself,the suspension tension of the catenary and the environmental atmosphere,are all important factors for the stress corrosion cracking of the catenary.In addition,the single wire of Cu-Mg alloy catenary has a large amount of cold working deformation,a high degree of work hardening,and a large participating stress.The grain size at the crack of the failed sample is small,and the proportion of the grain boundary is relatively large,giving the propagation of stress corrosion cracks a positive promotion.
作者
王远东
WANG Yuandong(China Railway Construction Electrification Bureau Group Kang Yuan New Materials Co.,Ltd.,Jiangyin 214521,Jiangsu,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2022年第S02期403-407,共5页
Materials Reports
关键词
高速铁路
承力索
力学性能
显微组织
失效机理
high speed railway
catenary
mechanical property
microstructure
failure mechanism
