Simulation and Discussion on the Decreasing Flow Stress Scale Effect

doi:10.1007/s12204-012-1274-0

Abstract

Abstract: The miniaturization of products requires the mass production of microparts. The microforming can well meet this requirement. Due to the emergence of decreasing flow stress scale effect in the micro scale, the traditional forming process and theory may fail. Based on the crystal plasticity theory, upsetting tests of micro copper cylinders with different dimensions and grain sizes were simulated, and the decreasing flow stress scale effect was studied and discussed. Results show that with the decrease of billet dimensions, the flow stress is gradually decreased, and the decreasing flow stress scale effect is emerged; with the increase of grain size, the decreasing flow stress scale effect is more remarkable. It can also be seen that the decreasing flow stress scale effect can be well simulated with the crystal plasticity theory, and the necessary relevant information is provided for deeper understanding on this scale effect, as well as the design of processes and die structures in the microforming.

Key words: microforming| scale effect| crystal plasticity| numerical simulation

摘要： The miniaturization of products requires the mass production of microparts. The microforming can well meet this requirement. Due to the emergence of decreasing flow stress scale effect in the micro scale, the traditional forming process and theory may fail. Based on the crystal plasticity theory, upsetting tests of micro copper cylinders with different dimensions and grain sizes were simulated, and the decreasing flow stress scale effect was studied and discussed. Results show that with the decrease of billet dimensions, the flow stress is gradually decreased, and the decreasing flow stress scale effect is emerged; with the increase of grain size, the decreasing flow stress scale effect is more remarkable. It can also be seen that the decreasing flow stress scale effect can be well simulated with the crystal plasticity theory, and the necessary relevant information is provided for deeper understanding on this scale effect, as well as the design of processes and die structures in the microforming.

关键词: microforming| scale effect| crystal plasticity| numerical simulation

CLC Number:

TG 301

SHEN Yu1 (申昱), YU Hu-ping1 (于沪平), DONG Xiang-huai1 (董湘怀), GUO Bin (郭斌)2. Simulation and Discussion on the Decreasing Flow Stress Scale Effect[J]. Journal of shanghai Jiaotong University (Science), 2012, 17(3): 306-311.

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