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Journal of Failure Analysis and Prevention

, Volume 11, Issue 1, pp 10–16 | Cite as

Fracture Failure Analysis of Ductile Cast Iron Crankshaft in a Vehicle Engine

  • Xue-qin Hou
  • Ying Li
  • Tao Jiang
Case History---Peer-Reviewed

Abstract

The engine crankshaft of a vehicle suddenly fractured, as the vehicle was running normally on a highway. The engine crankshaft was made from ductile cast iron. The failure cause was analyzed by chemical and metallographic examination, evaluation of mechanical properties, determination of depth of the quenched layer, measurement of distance between the quenched layer and the web, observation on the fracture surface as well as value determination of the fillet radius. The results showed that the failure mechanism of the crankshaft was fatigue fracture resulting from co-effect of bending and twisting, and the crack originated from the subsurface shrinkage in the unquenched layer of the crankshaft journal. Several aspects of the crankshaft were not up to the technical standards, such as distance between the quenched layer and the web, chemical composition, hardness and microstructure of the quenched layer, yield strength, and impact toughness.

Keywords

Failure analysis Crankshaft Fatigue fracture Shrinkage 

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Copyright information

© ASM International 2010

Authors and Affiliations

  1. 1.AVIC Failure Analysis CenterBeijing Institute of Aeronautical MaterialsBeijingChina

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