EFFECT OF TOOL GEOMETRY AND PROCESS PARAMETERS ON MATERIAL FLOW IN FSW OF AN AA 2024-T351 ALLOY

摘要

In this study the temperature distribution and the flow pattern of an embedded marker material were investigated when friction stir butt welding 4 mm thick 2024-T351 aluminium alloy plate using several welding tool combinations. Friction stir welded plates not embedded with the marker material were tested for micro-hardness and static tensile strength. Results indicated that the ultimate tensile strength of the friction stir welded material could be increased to values approaching that of the base material. The improvement in mechanical strength was found to depend largely on tool geometry in conjunction with weld travel speed. Tool geometry not only influenced the temperatures and micro-hardness experienced for both sides of the weld but also the marker material flow during joining. A micro-computer tomographic investigation of the marker flow indicated that the geometry of the welding tool pin had a significant influence on the material transport and distribution between each side of the interfacing workpieces.