Investigation of deformation size effects during microextrusion

Sunal Ahmet Parasiz*, Brad Kinsey, Neil Krishnan, Jian Cao, Ming Li

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

Abstract

Microextrusion has recently emerged as a feasible manufacturing process to fabricate metallic micropins having characteristic dimensions on the order of less <1 mm. At this length scale, the deformation of the workpiece is dominated by the so-called size effects, e.g., material property and frictional behavior variations at small length scales. In extrusion experiments performed to produce submillimeter-sized pins having a base diameter of 0.76 mm and an extruded diameter of 0.57 mm, the extruded pins exhibited a curving tendency when a workpiece with a relatively coarse grain size of 211 μm was used. This phenomenon was not observed when workpieces with a finer grain size of 32 μm were used. In this paper, results from microhardness tests and microstructure analyses for both grain sizes are presented to investigate this phenomenon and to characterize the deformation during microextrusion. The results obtained from this analysis show that as the grain size approaches the specimen feature size, the deformation characteristics of the extruded pins are dominated by the size and location of specific grains, leading to a nonuniform distribution of plastic strain and measured hardness and, thus, the curving tendency. Microhardness tests of the initial billet material and tensile test specimens are also presented as supplementary analyses.

Original languageEnglish (US)
Pages (from-to)690-697
Number of pages8
JournalJournal of Manufacturing Science and Engineering, Transactions of the ASME
Volume129
Issue number4
DOIs
StatePublished - Aug 1 2007

Keywords

  • Grain size
  • Microextrusion
  • Microhardness
  • Size effect

ASJC Scopus subject areas

  • Industrial and Manufacturing Engineering
  • Mechanical Engineering

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