Comparative HAZ softening analysis of three different automotive aluminum alloys by physical simulation

Abstract

The development of high-strength aluminum alloy has revolutionized the automotive industry with innovative manufacturing and technological processes to provide high-performance components and weight reduction and also diversified the application field and design considerations for the automotive parts that work under severe conditions, but the selection of proper production parameters is the most challenging task to get excellent results. Growing industrial demand for aluminum alloys led to the development of new welding technologies, processes, and studies of the effects of various parameters for its intended purposes. The microstructural changes that lead to loss of hardening and thereby mechanical strength in the HAZ welded joint even though the base materials are heat treatable and precipitation hardened. So, our goal is to analyze HAZ softening and analyze the subzones as a function of parameter. In this paper, the influence of the weld heat cycle on the heat-affected zone (HAZ) is physically simulated for Tungsten Inert Gas Welding (TIG) using the Gleeble 3500 thermomechanical simulator for three different automotive aluminum alloy (AA5754H22, AA6082 T6 & AA7075T6) plates of 1 mm thickness. In order to simulate the subzones of the heat-affected zone, samples were heated to four different HAZ peak temperatures (550°C, 440°C, 380°C, and 280°C) and two linear heat inputs (100 J/mm and 200 J/mm) by the application of the Rykalin 2D model. A series of experiments were performed to understand the behavior, which makes it possible to measure the objective data on the basis of the obtained image of the aluminum alloys tested with heat-affected zone tests in a Gleeble 3500 physical simulator. The main objective is to achieve the weldability of three different automotive aluminum alloys and their comparison based on the welding parameters like heat input. Further, the investigation of HAZ softening and microstructure of the specimens was tested and analyzed using the Vicker’s hardness test and optical microscope, respectively. The paper focuses on HAZ softening analysis of different grades of aluminium alloys for automotive applications.