Microstructure Analysis of Cold Worked Holes


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The cold expansion technique is often used to introduce beneficial compressive residual stresses at fastener holes that retard cracking in fatigue loaded material. The present investigation emphasizes micro structural changes along the radial section of holes after the holes are subjected to cold working. The experiment was conducted for two different materials, namely Steel85, EN-8D alloy steel with thickness 10mm. The holes are expanded to different percentages by split sleeve method and the microstructures are observed using SEM (Scanning Electron Microscope). It is observed from the micrographs that a zone of plastic deformation close to the hole followed by a zone of elastic compression induced by the split sleeve expansion. A comparative study of microstructure of the hole before and after expansion and also study the pattern after different extent of expansion of holes



Materials Science Forum (Volumes 539-543)

Main Theme:

Edited by:

T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran




S. Nagaraj and M. Krishna, "Microstructure Analysis of Cold Worked Holes", Materials Science Forum, Vols. 539-543, pp. 2222-2227, 2007

Online since:

March 2007




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