Fabrication of light weight materials having ultrafine grain structure through friction stir processing

Research Project

Project/Area Number	13450300
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	Material processing/treatments
Research Institution	SHIBAURA INSTITUTE OF TECHNOLOGY
Principal Investigator	OTSUKA Masahisa SHIBAURA INST OF TECH, Professor, 工学部, 教授 (20013732)
Co-Investigator(Kenkyū-buntansha)	FUJIWARA Masami NIHON UNIV, ENGINEERING PROF., 工学部, 教授 (40156930) 山縣裕ヤマハ発動機(株), 基盤技術研究所, 主任技師
Project Period (FY)	2001 – 2002
Project Status	Completed (Fiscal Year 2002)
Budget Amount *help	¥13,700,000 (Direct Cost: ¥13,700,000) Fiscal Year 2002: ¥5,100,000 (Direct Cost: ¥5,100,000) Fiscal Year 2001: ¥8,600,000 (Direct Cost: ¥8,600,000)
Keywords	FSW / FRICTION STIR WELDING / ALUMINUM ALLOY / MICROSTRUCTURE / GRAIN SIZE / MECHANICAL PROPERTY / SUPERPLASTICITY / RECRYSTALLIZATION / 摩擦攪拌接合
Research Abstract	Friction stir processing (FRP) has been exploited to cast aluminum alloy ADC12 and wrought aluminum alloy A5083 in order to refine the grain diameter. The processing was performed with an ordinary milling machine. A sheet specimen of both alloys subjected to FSP without any special pretreatment and its microstructure-property relationship was experimentally examined. The results are summarized as follows 1) The optimum condition for FSP under which no 3-D defects are formed, was determined as a revolution speed of 985rpm and transition speed of 88mm/min for both alloys 2) FSP brought about a microstructure consisting of fine and equi-axed grains with an average diameter of several μm 3) The grain diameter tended to decrease with decrease in the number of FSP for both alloys 4) Large plate-like phase of silicon in the starting material of ADC12 alloy changed to a number of uniform and spheroidal particles of several μm in diameter 5) FSPed specimens showed the mechanical properties at room temperature considerably close to those of parent material 6) Cast alloy specimen of alloy ADC12 subjected to FSP showed superplastic elongation larger than 500% at high temperature, probably due to the fine grain structure brought about by FSP