Failure Analysis of a Pellet-Mill Die

Author

Mario F. Buchely, Missouri University of Science and TechnologyFollow
Henry A. Colorado

Abstract

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.

Recommended Citation

M. F. Buchely and H. A. Colorado, "Failure Analysis of a Pellet-Mill Die," Journal of Failure Analysis and Prevention, vol. 16, no. 2, pp. 285 - 292, Springer New York LLC, Apr 2016.

The definitive version is available at https://doi.org/10.1007/s11668-016-0085-2

Department(s)

Materials Science and Engineering

Keywords and Phrases

Failure analysis; Fractography; Martensitic stainless steels; Metallographic examination; Pellet-mill

International Standard Serial Number (ISSN)

1547-7029; 1864-1245

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2016 ASM International, All rights reserved.

Publication Date

01 Apr 2016