Stir zone microstructure and strain rate during Al 7075-T6 friction stir spot welding

被引：151
作者：
Gerlich, A. [1 ]
Avramovic-Cingara, G. [1 ]
North, T. H. [1 ]
机构：
[1] Univ Toronto, Dept Mat Sci & Engn, Toronto, ON M5S 3E4, Canada
来源：
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE | 2006年 / 37A卷 / 09期
基金：
加拿大自然科学与工程研究理事会;
关键词：
D O I：
10.1007/BF02586110
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
The factors determining the temperature, heating rate, microstructure, and strain rate in Al 7075-T6 friction stir spot welds are investigated. Stir zone microstructure was examined using a combination of transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) microscopy, while the strain rate during spot welding was calculated by incorporating measured temperatures and the average subgrain dimensions in the Zener-Hollomon relation. The highest temperature during friction stir spot welding (527 degrees C) was observed in spot welds made using a tool rotational speed of 3000 rpm. The stir zone regions comprised fine-grained, equiaxed, fully recrystallized microstructures. The calculated strain rate in Al 7075-T6 spot welds decreased from 650 to about 20 s(-1) when the tool rotational speed increased from 1000 to 3000 rpm. It is suggested that the decrease in strain rate results when tool slippage occurs when the welding parameter settings facilitate transient local melting during the spot welding operation. Transient local melting and tool slippage are produced when the welding parameters produce sufficiently high heating rates and temperatures during spot welding. However, transient local melting and tool slippage is not produced in Al 7075-T6 spot welds made using a rotational speed of 1000 rpm since the peak temperature is always less than 475 degrees C.
引用
收藏
页码：2773 / 2786
页数：14
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