Prevention of Internal Cracks in Forward Extrusion by Means of Counter Pressure: A Numerical Treatise


Soyarslan C., TEKKAYA A. E.

STEEL RESEARCH INTERNATIONAL, cilt.80, ss.671-679, 2009 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 80 Konu: 9
  • Basım Tarihi: 2009
  • Doi Numarası: 10.2374/sri08sp170
  • Dergi Adı: STEEL RESEARCH INTERNATIONAL
  • Sayfa Sayıları: ss.671-679

Özet

In the context of forward bulk extrusion, where product defects are frequently observed, the effect of counter pressure on damage accumulation materializing a Continuum Damage Mechanics (CDM) approach is presented. A Lemaitre variant damage model accounting for unilateral damage evolution coupled with a multiplicative finite plasticity is utilized for this purpose. After a presentation of the crack governing mechanism, it is demonstrated that application of counter pressure introduces a marked decrease in the central damage accumulation, which in turn increases the formability of the material through keeping the tensile triaxiality in tolerable limits. It is also shown that, for a crack involving process, through systematic increase of the counter pressure, the crack sizes diminish; and at a certain level of counter pressure chevron cracks can be completely avoided.