Failure Analysis of a Pellet-Mill Die
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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.
Keywords
Fractography Failure analysis Metallographic examination Martensitic stainless steels Pellet-millReferences
- 1.R. Hoefnagels, M. Junginger, A. Faaij, The economic potential of wood pellet production from alternative, low-value wood sources in the southeast of the us. Biomass Bioenergy 71, 443–454 (2014)CrossRefGoogle Scholar
- 2.K. Behnke, Pellet mill performance as affected by mineral source (feed processing), FeedstuffsGoogle Scholar
- 3.A.R. Celma, F. Cuadros, F. López-Rodríguez, Characterization of pellets from industrial tomato residues. Food Bioprod. Process. 90(4), 700–706 (2012)CrossRefGoogle Scholar
- 4.California Pellet Mill Company (CPM), The pelleting process (March 2015). http://www.cpm.net/downloads/Animal%20Feed%20Pelleting.pdf
- 5.O. Fasina, S. Sokhansanj, Storage and handling characteristics of alfalfa pellets. Powder Handl. Process. 8(4), 361–366 (1996)Google Scholar
- 6.D. Nilsson, S. Bernesson, P.-A. Hansson, Pellet production from agricultural raw materials: a systems study. Biomass Bioenergy 35(1), 679–689 (2011)CrossRefGoogle Scholar
- 7.California Pellet Mill Company (CPM), Pellet-Mill CPM 7730 manual (1995)Google Scholar
- 8.California Pellet Mill Company (CPM), Dies and die selection (March 2015). http://www.cpm.net/downloads/Dies%20and%20Selection.pdf
- 9.Steel Founder’s Society of America, Steel casting handbook, supplement 8, high alloy data sheets corrosion series. (2004). http://www.sfsa.org/sfsa/pubs/hbk/s8.pdf
- 10.L. Alvarez, C. Garcia, V. Lopez, Continuous cooling transformation in martensitic stainless steel. ISIJ Int. 34(6), 516–521 (1994)CrossRefGoogle Scholar
- 11.ASM Metals Handbook, Volume 1. Properties and Selection: Irons, Steels, and High-Performance Alloys, ASM International, 1990Google Scholar
- 12.D. McBride, T. Dancy, Continuous Casting (Interscience Publishers, New York, 1962)Google Scholar
- 13.C. Garcia de Andres, G. Caruana, L. Alvarez, Control of m 23 c 6 carbides in 0.45C–13Cr martensitic stainless steel by means of three representative heat treatment parameters. Mater. Sci. Eng. A 241(1), 211–215 (1998)CrossRefGoogle Scholar