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Forming of low-ductility materials under hydrostatic pressure

  • Published:
Journal of Materials Shaping Technology

Abstract

The conditions required to hydrostatically extrude low ductility materials are evaluated. Experimental data on the influence of hydrostatic pressure on the fracture of an Al-SiC composite and a Ni3Al compound are used to construct diagrams which show the limitations of various types of extrusion and drawing processes. The results have applicability in the selection of forming operations for brittle alloys and composites.

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Abbreviations

A:

=cross-sectional area after extrusion

Ao :

cross-sectional area of billet

B:

work hardening rate in linear hardening law

F:

correction factor for extrusion stress to account for die friction

G:

component of extrusion stress due to redundant work

K:

work hardening constant in power law

n:

work hardening exponent in power law

p:

hydrostatic pressure

pB :

back pressure

pE :

extrusion pressure

q:

die pressure

w:

slope of σF vs.p plot

α:

dimensionless pressure parameter [=Pe/(Pe + σt)]

∈:

effective plastic strain

σ:

effective flow stress

σ1,σ2,σ3 :

principal stresses

σavg :

average flow stress

σEff :

effective extrusion stress

σFO :

fracture stress atp = 0

σF :

effective stress at fracture

σt :

tensile stress applied at die exit

σy :

initial yield stress

References

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  11. F. Zok, J.D. Embury, M.F. Ashby, and O. Richmond, unpublished work.

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Authors and Affiliations

  1. Materials Department, University of California, 93106, Santa Barbara, CA, USA

    F. Zok

  2. Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, L8S 4L7, Hamilton, Ontario, Canada

    J. D. Embury

Authors
  1. F. Zok
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  2. J. D. Embury
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Zok, F., Embury, J.D. Forming of low-ductility materials under hydrostatic pressure. J. Materials Shaping Technology 8, 77–81 (1990). https://doi.org/10.1007/BF02833618

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  • DOI: https://doi.org/10.1007/BF02833618

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