Regular Article

Effects of process parameters on tensile strength of friction stir welded Al-Cu double-layer sheets

School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran

^* e-mail: sedighi@iust.ac.ir

Received: 21 September 2019
Accepted: 19 June 2020

Abstract

In this paper, friction stir welding (FSW) process was used to join double-layer sheets of pure copper and 1050 aluminum alloy produced by explosive welding (EXW). The double-layer sheets were arranged side by side to perform friction stir butt-welding. In this regard, rotary FSW tools with different geometries were used at rotational speeds of 800 and 1250 rpm and linear speeds of 8, 12, and 20 mm min^‑1, in one and two number of passes. According to the results, the sample welded by a conical tool with a rotational speed of 800 rpm and a linear speed of 12 mm min^‑1 in one pass offered the highest tensile strength, which was approximately equivalent to the 84% of the strength of the raw double-layer sheet. In addition, applying the second FSW pass and using a threaded tool from the aluminum side had negative effects on the tensile strength. The microstructural evaluation showed the presence of more intermetallic phases including Al₄Cu₉, AlCu, and Al₂Cu in the sample welded by the threaded tool from the aluminum side in two number of passes, which was the responsible of the lower tensile strength and the higher microhardness.