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The visioplastic method for analysis of large extrusion strains

Technical Report ·
OSTI ID:7021957
 [1];  [2]
  1. Westinghouse Savannah River Co., Aiken, SC (USA)
  2. Georgia Inst. of Tech., Atlanta, GA (USA). School of Civil Engineering
Large plastic strains are produced when a metal billet is pressed through an extrusion die. This paper describes a method for obtaining the distribution of these strains during axisymmetric extrusion. The method is experimental-numerical and is based on a study of laminar flow lines produced in the extruded material. Several results are obtained using this analysis. These include the effects of extrusion tooling temperature and extrusion ratio. The method is also modified to study extrusion of powder metal, where the variable density invalidates the usual assumption of incompressibility. The flowline-strain relationship was originally set forth by Thomsen, Yang and Kobayashi and is referred to as viscoplasticity. The method described in this paper proceeds from that developed by Medrano and Gillis for axisymmetric extrusion. There are several differences. The experimental procedure has been changed to permit extrusion analysis at the high aluminum forming temperature (up to 430{degrees}C), thus allowing temperature effects to be studied. Numerical improvements permit the analysis at high extrusion ratios. The flow function has been redefined to permit the study of variable density material. 6 refs., 8 figs., 1 tab.
Research Organization:
Westinghouse Savannah River Co., Aiken, SC (USA)
Sponsoring Organization:
DOE/DP
DOE Contract Number:
AC09-89SR18035; AC09-76SR00001
OSTI ID:
7021957
Report Number(s):
WSRC-MS-90-14; ON: DE90007360
Country of Publication:
United States
Language:
English