Mechanical Engineering Faculty Research

Title

An Investigation of Friction During Friction Stir Welding of Metallic Materials

Document Type

Article

Publication Date

Winter 2-26-2009

Abstract

The technique of friction stir welding (FSW) puts effective use frictional heat for the purpose of joining metallic materials. In this research article, we present and discuss an experimental method to determine the coefficient of friction during FSW. The experiments were conducted to study the interaction between the FSW tool (a die steel) and the base metal (a high strength aluminum alloy) at various contact pressures (13 MPa, 26 MPa, and 39 MPa) and rotation speeds (200 rpm, 600 rpm, 1000 rpm, and 1400 rpm). The experimental results, the microstructure, and the process temperature reveal the experimental setup to be capable of simulating the conditions during FSW. The coefficient of friction was found to vary from 0.15 to 1.4, and the temperature increased to as high as 450°C. The coefficient of friction was found to increase with temperature. There exists a critical temperature at which point a steep increase in the coefficient of friction was observed. The critical temperature decreases from 250°C at a contact pressure of 26 MPa to 200°C at contact pressure of 34 MPa. Below the critical temperature at a specific contact pressure the maximum coefficient of friction is 0.6, and above the critical temperature it reaches a value as high as 1.4. The steep increase in the coefficient of friction is found to be due to the seizure phenomenon and the contact condition during FSW between the tool and the workpiece (base metal) is found to be sticking.

Publication Title

Materials and Manufacturing Processes

Volume

24

Issue

4

First Page

438

Last Page

445