An investigation on the failed blades in a locomotive turbine

作者：Xu Xiaolei^*; Yu Zhiwei

来源：Engineering Failure Analysis, 2007, 14(7): 1322-1328.

DOI：10.1016/j.engfailanal.2006.11.041

• turbo blades
• multiple-origin fatigue fracture
• over-heat damage

A failure investigation has been conducted on the turbine blades used in a locomotive turbochanger, which are made from K418 Ni-base superalloy. Fractography investigation on the troubled blade indicates that cracks initiated from the surface of the concave side close to the trailing edge and propagated towards to the leading edge. The multi-origin fatigue fracture is the dominant failure mechanism of the blade. Metallographic morphology typical of over-heat damage features, such as re-dissolution of the eutectic gamma + gamma', melting of the local region of the grain boundary appears in the microstructure of the airfoil part of the failed blades. Appearance of over-heat damage structure in the serviced blades makes the strength of the blade material decrease intensely to initiate fatigue cracks and make one of the blades fracture first. Fragments from the blade fractured first would crash the other blades to make the blades break or bending deformation.

• 出版日期2007-10
• 单位大连海事大学