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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.43  No.11 (2002)  >  pp.2908-2912

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Factors Affecting Bend Formability of Tempered Copper Alloy Sheets

Kouichi Hatakeyama1), Akira Sugawara2), Takuya Tojyo3) and Keisuke Ikeda3)
1) Manufacturing Division, DOWA Metal Co., LTD.
2) Metallic Materials Laboratory, DOWA Mining Co., LTD.
3) Depertment of Materials Processing, Graduate School of Engineering, Tohoku University

Uniform deformation of tempered copper alloy sheets is small, and their bend formability depends largely on the amount of non-uniform deformation, which is complicatedly influenced by other factors in addition to the work-hardening exponent n. In this study, it has been shown that post-uniform elongation in the tensile test can be represented by two parameters, (efeu) and f. The symbol ef is the nominal strain at the breakage point, eu the uniform elongation and f the parameter giving the degree of strain localization along the tensile axis. Good correlation between those parameters and bend formability was ascertained by experimental studies on C51900 and some other Cu alloy sheets. The experimental results showed that the introduced two parameters were not independent variables but mutually related. In addition, the nucleation and growth processes of surface wrinkles in bending, which finally led to cracking, were studied metallographically. A lot of micro necks first arose in the vicinity of grain boundaries, and part of them developed into the groove of wrinkles. Spacing between grooves appeared to correspond with the size and distribution of cube-oriented grains.

copper alloy sheet, uniform elongation, n value, post-uniform elongation, strain localization, bend formability

Received: August 02, 2002
Accepted: September 20, 2002 , Published online: September 06, 2005
Copyright (c) 2005 The Japan Institute of Metals



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