The Preliminary Exploration of Micro-Friction Stir Welding Process and Material Flow of Copper and Brass Ultra-Thin Sheets.

Changqing Zhang,Shuwen Wang,Wenchen Shi,Zhuo Qin,Chen Rong

doi:10.3390/ma13102401

Abstract

In the friction stir welding (FSW) of ultra-thin dissimilar metal sheets, different physical material properties, the reduction of plastic metal in the weld zone, and insufficient plastic metal flow lead to poor weld seam shapes and joint qualities. Therefore, it is necessary to study the flow behavior during the FSW of ultrathin sheets. In this study, micro friction stir welding (μFSW) was conducted and analyzed for the butt welding of 0.6-mm-thick ultrathin brass (H62-H) and pure copper (T2-Y) sheets. By analyzing the electric signals of the temperature and force during the welding process, testing the mechanical properties, and analyzing the metallography of the joint, the influences of the process parameters on the metal flow behavior during μFSW were studied. In the proper process conditions, the material preferentially migrated and concentric vortex flow occurred in the vicinity of the shoulder and tool pin action areas. The copper was pushed from the retreating side (RS) to the advancing side (AS) of the weld, allowing it to flow more fully. A mixture of both materials formed at the bottom of the weld nugget, and less migration occurred in the heat-affected zone of the AS at this time. The highest tensile strength can reach 194 MPa, accounting for 82.6% of the copper. The presence of brittle phases Cu5Zn8, AgZn3 and AgZn caused the hardness to fluctuate slightly.

Highlights

With the rapid development of aviation, aerospace, electronics, energy, and other industrial fields, product components are becoming increasingly miniaturized, and the demand for micro-connection technology is increasing
Micro-friction stir welding for sheets with thicknesses less than 1 mm was developed based on traditional Friction stir welding (FSW), and it is typically a high rotation speeds process [3,4]
The results suggested that the joint strength underwent a regular change under the effect of the speed field

Summary

Introduction

With the rapid development of aviation, aerospace, electronics, energy, and other industrial fields, product components are becoming increasingly miniaturized, and the demand for micro-connection technology is increasing. Copper and its alloys are the preferred materials for lightweight, miniaturized, precision, intelligent and complex processes owing to their unique properties, such as their good electrical conductivities, thermal conductivities, ductilities, and corrosion resistance [1,2]. Friction stir welding (FSW) is an advanced solid-state joining technology that was invented by The. Welding Institute (TWI) in 1991. Micro-friction stir welding (μFSW) for sheets with thicknesses less than 1 mm was developed based on traditional FSW, and it is typically a high rotation speeds process [3,4]. For copper and its alloys, in addition to the difficulties mentioned above, because of its generally high melting points and thermal conductivities it is more difficult for Materials 2020, 13, 2401; doi:10.3390/ma13102401 www.mdpi.com/journal/materials

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Results

Conclusion