Change search
ReferencesLink to record
Permanent link

Direct link
Improving the grain size in the forging of large copper lids
KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Computer Systems for Design and Manufacturing.
2006 (English)In: Journal of Materials Processing Technology, ISSN 0924-0136, Vol. 172, no 2, 264-270 p.Article in journal (Refereed) Published
Abstract [en]

Forging of large copper lids for cylindrical canisters meant for nuclear waste is treated. Based on recent full-scale experiments, an alternative way of forming is proposed. In the experiments, a press offering just a low force, 20 MN, was available. Two-step hot forging was used: upsetting of an ingot between flat and parallel tools followed by cogging for filling a die cavity. The initial ingot measured diameter 350 min and 1400 mm in height buckled and made repeated straightening during the upsetting necessary. This forming procedure showed a poor material yield and resulted in a coarse-grained microstructure in the lids close to the final midpoint contact surfaces. From a 2D FE-analysis it became clear that this structure is associated with the formation of dead metal regions. Coarse grains are not acceptable from mechanical and corrosion point of view and make ultrasonic testing unreliable. Thus, the present work is mainly focussed on improving the structure by presenting an alternative way of manufacturing, which at the same time is faster. The flat dies used in upsetting were furnished with a central protruding part of spherical shape and the cavity filling by cogging was replaced by ordinary closed-die forging. In this way large strains were obtained in the critical, low-strained regions. The modified two-step forging was simulated for different radii of the spheres, keeping their penetration depth constant. The tools designed for the closed-die forging should, according to the FE-analysis, fill the cavity with a moderate force and an acceptable material yield. According to an earlier investigation by the authors the here proposed way of forming should ensure a fine microstructure throughout the whole volume of the lids.

Place, publisher, year, edition, pages
2006. Vol. 172, no 2, 264-270 p.
Keyword [en]
grain size, forging, large copper lids, design
URN: urn:nbn:se:kth:diva-15486DOI: 10.1016/j.jmatprotec.2005.10.020ISI: 000235743300016ScopusID: 2-s2.0-32444447493OAI: diva2:333527
QC 20100525Available from: 2010-08-05 Created: 2010-08-05Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Ståhlberg, Ulf
By organisation
Computer Systems for Design and Manufacturing
In the same journal
Journal of Materials Processing Technology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 36 hits
ReferencesLink to record
Permanent link

Direct link