Gas Metal Arc Lap Joining of Aluminium Alloys and Steel Sheets

Abstract

A coupled experimental and theoretical investigation on joining of aluminium and galvanized sheets in lap joint geometry using an advanced pulsed current gas metal arc based process is presented. The experimental study was focussed on finding suitable processing conditions to restrict the heat input, and minimize the growth of the phase layer thickness and the formation of Fe-Al intermetallic compounds along the joint interface. The theoretical study included the development of a three-dimensional heat conduction model to compute the temperature field and thermal cycles, and estimate the final joint bead profiles and phase layer thickness as a function of processing conditions. The estimated results are tested extensively for a wide range of experimental conditions. The experimentally measured and the corresponding computed results show that the dissimilar material combinations of aluminium and galvanized steel can be joined successfully by pulsed current gas metal arc with a precise control of processing conditions and heat input.

Joining of aluminium alloy and galvanized steel sheets multimaterial assembly using a gas metal arc based process

“…The present work follows an experimental investigation and computer-based process simulation to estimate temperature fields, thermal cycles and corresponding thermomechanical Figure 1a depicts the solution domain and applied boundary conditions. In Figure 1a, h A refers to the convective heat transfer coefficient along the aluminium sheet surface, and hc 1 and hc 2 are two lumped heat transfer coefficients along the top and bottom of the steel surfaces, respectively [11].…”

“…The bead profile of the filler deposit in multi-material assembly of galvanized and aluminium sheets involves the spread of the molten filler on the steel surface, the width of the fusion zone in the aluminium side and the height of the filler wire deposit along the original edge of the aluminium sheet [11,12]. The filler deposit profile for the modeling was estimated a-priori as function of thermo-physical properties of filler wires and process conditions [11]. Table 3 presents the mechanical properties of the sheet and filler wire materials, which are considered for the analysis.…”

“…The K type thermocouples were fixed along the joint line and at the bottom of the steel sheet for monitoring of the thermal cycles [11]. The transverse section of the specimens were polished with P220 to P2400 grades of emery papers, 1 µm diamond grit paste and colloidal silica.…”

“…where k, ρ, C P , T and t depict thermal conductivity, density, specific heat, temperature and time, respectively. The term Q ׄ depicts volumetric heat generation per unit time as Equation 2 [11,12]…”

“…where η (~ 0.8), Δ, I A , V A illustrate the process efficiency, volume under the arc, average arc current and voltage, respectively. The volume under the arc is defined as the product of arc diameter and cross-sectional area of filler wire deposit profile with one element layer thickness in both aluminium and steel sheets [11,12]. melting temperature of steel of 1053 K. The experimentally measured and the corresponding computed bead widths are 5.45 mm and 4.95 mm, respectively.…”