The Study of Microstructure and Mechanical Properties of Fine-grained Cu-40%Zn Alloy Fabricated by Friction Stir ProcessingFabricated by Friction Stir Processing

• Main Authors: Gen-wei Jhou, 周根葦
• Other Authors: Po-We Kao
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/38498700421845202888

碩士 === 國立中山大學 === 材料與光電科學學系研究所 === 101 === In this work, fine-grained Cu-40%Zn brass was produced by friction stir processing (FSP). The severe plastic deformation (SPD) and hot deformation provided by FSP could effectively refine the grains. By using proper heat treatment, two different proportions of α/β dual-phase structure were produced, which were subsequently processed by different FSP parameters to form fine-grained structure. The effect of FSP parameters on the microstructure and mechanical properties was studied. The microstructure was characterized by using transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD), and both microhardness and tensile test were used to measure the mechanical properties. A dual-phase structure with 30% β-phase was obtained by annealing the alloy at 700oC for 1 hour and water quenching to room temperature. After FSP, the alloy contains nearly complete α-phase in all processing conditions, in which the grain size ranges from 1~6 μm. The grain size decreases as the tool rotation rate decreases or the tool transverse speed increases. An increase in FSP pass is the most effective way to refine the grain size and results in high strength. The study also indicates that a faster cooling rate in FSP could results in smaller grains by limiting grain growth.