V. Pintos, S. J. Chang, R. López, R. Montenegro, J. Vazquez, AIMEN, Porriño, Spain
Aluminum and its alloys has very good properties, this is the reason because it is a metal used in a wide range of applications. Aluminium has a very low weight and a high corrosion resistance that makes it useful in the shipbuilding, automotive, railway and aeronautic sectors. The Aluminum alloys are most frequently being used in the automotive sector, in order to reduce the vehicle weight and, as consequence, reducing fuel consumption and obtaining higher environmental benefits.
Gas Tungsten Arc Welding (GTAW) as an automated process, has the capability to get joints of an excellent weld quality with high welding speeds. This results in less distortion and narrower heat affected zones, much better than the manual technique that requires a good degree of welder skill.
This research work presents the study of the influence of Aluminum oxide film (Alumina) in the weldability of the alloy AA5754 H111 and the steps to get seam beads of enough quality in order to satisfy the high requirements of the final automotive builder. Two of the most important joints used in automotive sector were studied (butt and lap joints). With the intention of maintain the same quality using automatic GTAW process, it is important to focus on the joint preparation. Different parameters were studied such as mechanical cutting, (sawing, grinding, shearing and thermal cutting), jigs and welding fixtures and superficial treatments (no cleaning, diverse types of chemical and mechanical cleaning). These factors were important to check the influence of the Alumina layer in the welding defects.
To study the effects of the variables in the results of these joint designs, a geometric-qualitative analysis was made for measuring Alumina thickness and its different chemical compositions.
Analyses were taken to quantify the weld beads defects: Scanning Electron Microscopy, optical metallography, radiographic examination and mechanical testing.
Summary: GTAW as an automated process has the capability to get joints of an excellent weld quality with high welding speeds, for joining aluminium alloys in the automotive sector. This research work presents the study of the influence of Alumina and other factors, in the weldability of the alloy AA5754 H111.
