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Grain size as influenced by process parameters in copper extrusion
KTH, Superseded Departments, Production Engineering.
2001 (English)In: Scandinavian journal of metallurgy, ISSN 0371-0459, Vol. 30, no 4, 232-237 p.Article in journal (Refereed) Published
Abstract [en]

Today, different methods and materials are investigated for the manufacturing of large canisters meant for encapsulation of nuclear waste. One method of interest includes hot extrusion of coarse-grained copper ingots. It has been shown that the grain size in the final product must be small in order to enable ultrasonic testing and to guarantee high resistance towards creep and corrosion. Different codes are being developed for predicting the final grain size as influenced by temperature, strain and strain rate. In the present work, these parameters have been determined by simulations for different material elements during extrusion of cylindrical copper billets. Elements, located at various distances from the central axis of the initial workpiece, were traced from the inlet to the outlet of the die by utilizing the FE-code FORM2D. In this way, the parameters describing the deformation history of the elements were determined as functions of time. Experiments corresponding to the simulations were carried out. Starting with billets in as-cast condition, the final grain sizes were evaluated. It is concluded that the initial grain size of an as-cast cylindrical billet is heavily decreased for all the extrusion conditions studied. The investigation was carried out for different working temperatures, 550, 650 and 750 degreesC and extrusion ratios, 10 and 15. The final grain size was found within the interval 23-37 mum. The smallest grain size was, for each working condition, located close to the surface of the extrudate where the largest strains and temperature increases occurred. Low extrusion temperatures gave the best results.

Place, publisher, year, edition, pages
2001. Vol. 30, no 4, 232-237 p.
Keyword [en]
hot extrusion, copper, grain size
URN: urn:nbn:se:kth:diva-20832ISI: 000170134100006OAI: diva2:339529
QC 20100525Available from: 2010-08-10 Created: 2010-08-10Bibliographically approved

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Ståhlberg, Ulf
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