STUDIES OF WELDING OF SHEET METAL BY GAS METAL ARC WELDING PROCESS

Abstract

This project deals with the joining of steel to aluminium. The main objective of this present thesis is to study the joining of steel to aluminum by pulse arc Gas Metal Arc Welding Process using Al-Si5 wire. The main problem of joining steel to aluminum by normal GMAW process is the formation of fragile intermetalic phases that cause the poor mechanical performance of the assembly. Pulse GMAW process incorporated the benefits of axial spray transfer- clean, spatter free welds having excellent fusion, with lower heat input resulting in a limitation of the growth of fragile phases In this dissertation work tested with eight different types of coated for comparison purposes. Sheet thicknesses were in the range 1 to 1.5 mm. For another adding partner we used AA 6016 alloy sheet of the thickness of 1.15mm. The used filler material was A1Si5 with a diameter of 1.2mm. All the trials were accomplished by lap joint with a lap amount of 10mm and with aluminium on the top side. We also tried with and without fluxing agent as well as with and without backing material and also with different setoffs of welding torch to see their influences. Moreover we tried Gas Tungsten Arc Welding process without any filler material to compare the results with the Gas Metal Arc welding process. In the last phase of our dissertation work, we carried out mechanical testing to characterize the mechanical properties of the joint. We also carried out the EDX (Energy Dispersive X-ray) analysis in order to explore the chemical composition of the weld seam. Micro hardness test and tensile test were carried out to characterize the hardness, ultimate strength, - yield strength and also elongation of the assemblies. Fracture mechanics of the joint will be analyzed by a detailed characterization of the seam by scanning electron microscopy.