Failure Analysis of a Fractured Wrench Socket
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Failure of a 13/16 in. wrench socket while hand tightening a socket was investigated using hardness test, optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy techniques. Hardness and microstructure of the fractured socket are compared with those of other original (unfailed) wrench sockets from other manufacturers. Wrench material is a low carbon steel, and socket was manufactured in a powder metallurgy (PM) process. Results of this analysis indicate that non-uniform socket wall thickness, poor socket geometric design featuring sharp corners forming stress raisers, and poor sintering step in the PM process leaving unsintered particles were causes of the socket failure. The presence of the inclusions containing contaminants such as S and Al on the socket fracture surface may have played a role in this failure.
KeywordsInclusions Powder metal steels Sintered
- 1.J.E. Shigley, C.R. Mischke, R.G. Budynas, Mechanical Engineering Design, 7th edn. (McGraw Hill, New York, 2004), pp. 982–988Google Scholar
- 2.D.R. Askeland, P.P. Fulay, W.J. Wright, The Science and Engineering of Materials, 6th edn. (Cengage Learning, Stamford, 2011)Google Scholar
- 3.V. Kerlins, A. Phillips, Modes of Fracture, in Fractography, vol. 12. ASM Handbook (ASM International, Materials Park, 1987), pp. 12–71Google Scholar