Analysis on dynamic tensile extrusion behavior of UFG OFHC Cu

6th International Conference on Nanomaterials by Severe Plastic Deformation

材料科学;化学

Park, Kyung-Tae^1 ; Park, Leeju^2 ; Kim, Hak Jun^2 ; Kim, Seok Bong^2 ; Lee, Chong Soo^3

Department Mater. Sci. Eng., Hanbat National University, 305-719, Daejeon, Korea, Republic of^1

Agency for Defense Development, PO Box 35-42, 305-600, Daejeon, Korea, Republic of^2

GIFT, POSTECH, 790-784, Pohang, Korea, Republic of^3

关键词: Coarse-grained;    Commercial finite element codes;    Dynamic tensile extrusions;    High strain rates;    Johnson-Cook model;    ON dynamics;    Symmetric model;    Ultrafine-grained Cu;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/63/1/012144/pdf
DOI  :  10.1088/1757-899X/63/1/012144

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Dynamic tensile extrusion (DTE) tests with the strain rate order of ∼105s-1were conducted on coarse grained (CG) Cu and ultrafine grained (UFG) Cu. ECAP of 16 passes with route Bc was employed to fabricate UFG Cu. DTE tests were carried out by launching the sphere samples to the conical extrusion die at a speed of ∼475 m/sec in a vacuumed gas gun system. UFG Cu was fragmented into 3 pieces and showed a DTE elongation of ∼340%. CG Cu exhibited a larger DTE elongation of ∼490% with fragmentation of 4 pieces. During DTE tests, dynamic recrystallization occurred in UFG Cu, but not in CG Cu. In order to examine the DTE behavior of CG Cu and UFG Cu under very high strain rates, a numerical analysis was undertaken by using a commercial finite element code (LS-DYNA 2D axis-symmetric model) with the Johnson-Cook model. The numerical analysis correctly predicted fragmentation and DTE elongation of CG Cu. But, the experimental DTE elongation of UFG Cu was much smaller than that predicted by the numerical analysis. This difference is discussed in terms of microstructural evolution of UFG Cu during DTE tests.