Role of Mg in porous oxide scale growth formation on welded Al 6061 (Al-Mg-Si)

Abstract

High-temperature oxidation involving Al 6061 (Al-Mg-Si) alloy is often given wide attention in the metal fabrication and welding industry. It is caused by its specialty benefits such as good corrosion resistance, formability, and weldability mainly at room temperature. Al alloys are significantly less resistant to high-temperature oxidation, especially in welded and structural parts. This work aimed to identify the effects of high-temperature oxidation on welded joint Al 6061 by using ER 5356 (Al-5% Mg) filler metal. High-temperature oxidation test was performed by exposing welded Al 6061 (STK 5356) and ER 5356 filler metal (TLP 5356) samples in the Lindberg model furnace to hot air at 400 and 600 °C. The test was carried out at a fixed duration of 20 and 40 h at a pressure of 1 atm. The condition shows that the addition of ER 5356 filler metal, which has 5% Mg assists in thickening the surface porous oxide and acted as a non-protective layer consisting of MgO and MgAl2O4. Therefore, the use of ER 5356 filler metal is proposed for low-temperature applications that are below 400 °C when involving welded Al 6061.