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- Title
Failure Analysis of the Faulty Locomotive Coil Spring.
- Authors
He, Guang; Wu, Wangping
- Abstract
A certain locomotive coil spring was found to fracture prematurely after only 300,000 km of operation. This work employed a combination of experimental and finite element methods to analyze the failure reasons in detail. Firstly, fatigue crack originated from the first working coil adjacent to the support ring, and the fracture exhibited characteristics of low-cycle high-stress fatigue. Secondly, the chemical composition, microstructure, and microscopic morphology of the failed sample was characterized using inductively coupled plasma emission spectrometry, metallographic microscopy, and scanning electron microscopy, respectively. Mechanical properties of the spring were tested using a Rockwell hardness tester and a single-column pendulum-type impact testing machine. Chemical composition analysis of the failed spring indicated conformity to standards. Microscopic fracture analysis revealed quasi-cleavage fracture features, with noticeable fatigue striations and a small amount of ductile dimples were also found. In the absence of corrosion, the microstructure of the spring showed small secondary cracks and deformation marks near the crack source. Microstructures after corrosion revealed predominantly tempered troostite, and the spring's surface underwent an unexpected decarburization process, resulting in a fully decarburized layer with a depth of approximately 64 μm and a total decarburized layer depth of about 160 μm. The overall hardness of the failed spring was below the relevant technical specifications. Furthermore, based on the results of fracture analysis and finite element analysis, it was determined that the spring encountered abnormal conditions during its service period. Therefore, the premature failure of the spring occurred due to the combined effects of unexpected defects resulting from improper heat treatment and adverse service conditions. Finally, some suggestions and preventive measures are proposed for the spring.
- Subjects
HELICAL springs; FAILURE analysis; INDUCTIVELY coupled plasma spectrometry; LOCOMOTIVES; FATIGUE cracks; SPRING
- Publication
Journal of Failure Analysis & Prevention, 2024, Vol 24, Issue 3, p1199
- ISSN
1547-7029
- Publication type
Article
- DOI
10.1007/s11668-024-01911-z