Journal of Failure Analysis and Prevention

, Volume 16, Issue 2, pp 285–292 | Cite as

Failure Analysis of a Pellet-Mill Die

  • M. F. Buchely
  • H. A. Colorado
Technical Article---Peer-Reviewed


One of the most important parts for pellet-mills is the die, since the die transforms raw materials in small cylinders called pellets. In this paper, a failure analysis was conducted for a pellet-mill die that had not reached its service life expectancy. The failure analysis consist of a characterization of the material using atomic emission spectroscopy, hardness measurements, optical microscopy, scanning electron microscopy (SEM), and energy-dispersive spectroscopy by SEM. Additionally, visual inspection and fractography of the fracture surfaces and FE analysis were performed. It was found that the die material was a CA40 alloy, which microstructure consists of a martensitic matrix with finely dispersed carbides of the type M23C6. Also, a non-common level of inclusion type Al2O3 was found on the microstructure of the die material. According to the fractographic analysis, the crack initiation was located in a high-stress concentration region on the counterbored holes of the die, and also aided by the inclusions on the structure. Crack propagated along the material as an intergranular brittle fracture.


Fractography Failure analysis Metallographic examination Martensitic stainless steels Pellet-mill 


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Copyright information

© ASM International 2016

Authors and Affiliations

  1. 1.Structural Integrity Research Group, Mechanical Engineering DepartmentUniversidad de los AndesBogota DCColombia
  2. 2.CCComposites Lab.Universidad de Antioquia UdeAMedellinColombia

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